Browse
Submit Data
Databases
API
Help

Dataset Information

29 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Nonaggregated α-synuclein influences SNARE-dependent vesicle docking via membrane binding.

ABSTRACT: α-Synuclein (α-Syn), a major component of Lewy body that is considered as the hallmark of Parkinson's disease (PD), has been implicated in neuroexocytosis. Overexpression of α-Syn decreases the neurotransmitter release. However, the mechanism by which α-Syn buildup inhibits the neurotransmitter release is still unclear. Here, we investigated the effect of nonaggregated α-Syn on SNARE-dependent liposome fusion using fluorescence methods. In ensemble in vitro assays, α-Syn reduces lipid mixing mediated by SNAREs. Furthermore, with the more advanced single-vesicle assay that can distinguish vesicle docking from fusion, we found that α-Syn specifically inhibits vesicle docking, without interfering with the fusion. The inhibition in vesicle docking requires α-Syn binding to acidic lipid containing membranes. Thus, these results imply the existence of at least two mechanisms of inhibition of SNARE-dependent membrane fusion: at high concentrations, nonaggregated α-Syn inhibits docking by binding acidic lipids but not v-SNARE; on the other hand, at much lower concentrations, large α-Syn oligomers inhibit via a mechanism that requires v-SNARE interaction [ Choi et al. Proc. Natl. Acad. Sci. U. S. A. 2013 , 110 ( 10 ), 4087 - 4092 ].

SUBMITTER: Lai Y

PROVIDER: S-EPMC4075992 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Alpha-Synuclein Continues to Enhance SNARE-Dependent Vesicle Docking at Exorbitant Concentrations.

Project description:Recently, Parkinson's disease-associated α-synuclein (αS) has emerged as an important regulator for SNARE-dependent vesicle fusion. However, it is controversial if excessive accumulation of αS, even in the absence of aggregation, impairs neurotransmission. Here we use a single vesicle fusion assay with ms time resolution capable of dissecting the impact of αS on each step of membrane fusion. Unlike the previous results from various in vitro, cellular, and in vivo studies, we find that non-aggregated αS promotes vesicle merger even at exorbitant concentrations. The enhancement has been seen as much as 13 fold. Delving into the kinetics of the intermediate states for vesicle fusion reveals that αS stimulates vesicle docking without altering the dynamics of bilayer merger (lipid mixing). However, minute amounts of soluble aggregated species abolish SNARE-dependent bilayer merger completely. Thus, the results show that excessive accumulation of non-aggregated αS may not be toxic for neurotransmitter release.

| S-EPMC6437117 | biostudies-literature

Large α-synuclein oligomers inhibit neuronal SNARE-mediated vesicle docking.

Project description:Parkinson disease and dementia with Lewy bodies are featured with the formation of Lewy bodies composed mostly of α-synuclein (α-Syn) in the brain. Although evidence indicates that the large oligomeric or protofibril forms of α-Syn are neurotoxic agents, the detailed mechanisms of the toxic functions of the oligomers remain unclear. Here, we show that large α-Syn oligomers efficiently inhibit neuronal SNARE-mediated vesicle lipid mixing. Large α-Syn oligomers preferentially bind to the N-terminal domain of a vesicular SNARE protein, synaptobrevin-2, which blocks SNARE-mediated lipid mixing by preventing SNARE complex formation. In sharp contrast, the α-Syn monomer has a negligible effect on lipid mixing even with a 30-fold excess compared with the case of large α-Syn oligomers. Thus, the results suggest that large α-Syn oligomers function as inhibitors of dopamine release, which thus provides a clue, at the molecular level, to their neurotoxicity.

| S-EPMC3593925 | biostudies-literature

?-Synuclein may cross-bridge v-SNARE and acidic phospholipids to facilitate SNARE-dependent vesicle docking.

Project description:Misfolded ?-synuclein (A-syn) is widely recognized as the primal cause of neurodegenerative diseases including Parkinson's disease and dementia with Lewy bodies. The normal cellular function of A-syn has, however, been elusive. There is evidence that A-syn plays multiple roles in the exocytotic pathway in the neuron, but the underlying molecular mechanisms are unclear. A-syn has been known to interact with negatively charged phospholipids and with vesicle SNARE protein VAMP2. Using single-vesicle docking/fusion assays, we find that A-syn promotes SNARE-dependent vesicles docking significantly at 2.5?µM. When phosphatidylserine (PS) is removed from t-SNARE-bearing vesicles, the docking enhancement by A-syn disappears and A-syn instead acts as an inhibitor for docking. In contrast, subtraction of PS from the v-SNARE-carrying vesicles enhances vesicle docking even further. Moreover, when we truncate the C-terminal 45 residues of A-syn that participates in interacting with VAMP2, the promotion of vesicle docking is abrogated. Thus, the results suggest that the A-syn's interaction with v-SNARE through its C-terminal tail and its concurrent interaction with PS in trans through its amphipathic N-terminal domain facilitate SNARE complex formation, whereby A-syn aids SNARE-dependent vesicle docking.

| S-EPMC5772654 | biostudies-other

?-Amyloid and ?-synuclein cooperate to block SNARE-dependent vesicle fusion.

Project description:Alzheimer's disease (AD) and Parkinson's disease (PD) are caused by ?-amyloid (A?) and ?-synuclein (?S), respectively. Ample evidence suggests that these two pathogenic proteins are closely linked and have a synergistic effect on eliciting neurodegenerative disorders. However, the pathophysiological consequences of A? and ?S coexistence are still elusive. Here, we show that large-sized ?S oligomers, which are normally difficult to form, are readily generated by A?42-seeding and that these oligomers efficiently hamper neuronal SNARE-mediated vesicle fusion. The direct binding of the A?-seeded ?S oligomers to the N-terminal domain of synaptobrevin-2, a vesicular SNARE protein, is responsible for the inhibition of fusion. In contrast, large-sized A?42 oligomers (or aggregates) or the products of ?S incubated without A?42 have no effect on vesicle fusion. These results are confirmed by examining PC12 cell exocytosis. Our results suggest that A? and ?S cooperate to escalate the production of toxic oligomers, whose main toxicity is the inhibition of vesicle fusion and consequently prompts synaptic dysfunction.

| S-EPMC4414064 | biostudies-literature

Complexin-1 enhances the on-rate of vesicle docking via simultaneous SNARE and membrane interactions.

Project description:In synaptic terminals, complexin is thought to have inhibitory and activating roles for spontaneous "mini" release and evoked synchronized neurotransmitter release, respectively. We used single vesicle-vesicle microscopy imaging to study the effect of complexin-1 on the on-rate of docking between vesicles that mimic synaptic vesicles and the plasma membrane. We found that complexin-1 enhances the on-rate of docking of synaptic vesicle mimics containing full-length synaptobrevin-2 and full-length synaptotagmin-1 to plasma membrane-mimicking vesicles containing full-length syntaxin-1A and SNAP-25A. This effect requires the C-terminal domain of complexin-1, which binds to the membrane, the presence of PS in the membrane, and the core region of complexin-1, which binds to the SNARE complex.

| S-EPMC3854000 | biostudies-literature

Cooperative inhibition of SNARE-mediated vesicle fusion by α-synuclein monomers and oligomers.

Project description:The primary hallmark of Parkinson's disease (PD) is the generation of Lewy bodies of which major component is α-synuclein (α-Syn). Because of increasing evidence of the fundamental roles of α-Syn oligomers in disease progression, α-Syn oligomers have become potential targets for therapeutic interventions for PD. One of the potential toxicities of α-Syn oligomers is their inhibition of SNARE-mediated vesicle fusion by specifically interacting with vesicle-SNARE protein synaptobrevin-2 (Syb2), which hampers dopamine release. Here, we show that α-Syn monomers and oligomers cooperatively inhibit neuronal SNARE-mediated vesicle fusion. α-Syn monomers at submicromolar concentrations increase the fusion inhibition by α-Syn oligomers. This cooperative pathological effect stems from the synergically enhanced vesicle clustering. Based on this cooperative inhibition mechanism, we reverse the fusion inhibitory effect of α-Syn oligomers using small peptide fragments. The small peptide fragments, derivatives of α-Syn, block the binding of α-Syn oligomers to Syb2 and dramatically reverse the toxicity of α-Syn oligomers in vesicle fusion. Our findings demonstrate a new strategy for therapeutic intervention in PD and related diseases based on this specific interaction of α-Syn.

| S-EPMC8155056 | biostudies-literature

Effect of pseudorepeat rearrangement on alpha-synuclein misfolding, vesicle binding, and micelle binding.

Project description:The pathological and physiological hallmarks of the protein alpha-synuclein (aS) are its misfolding into cytotoxic aggregates and its binding to synaptic vesicles, respectively. Both events are mediated by seven 11-residue amphiphilic pseudorepeats and, most generally, involve a transition from intrinsically unstructured conformations to structured conformations. Based on aS interactions with aggregation-inhibiting small molecules, an aS variant termed shuffled alpha-synuclein (SaS), wherein the first six pseudorepeats had been rearranged, was introduced. Here, the effects of this rearrangement on misfolding, vesicle binding, and micelle binding are examined in reference to aS and beta-synuclein to study the sequence characteristics underlying these processes. Fibrillization correlates with the distinct clustering of residues with high beta-sheet propensities, while vesicle affinities depend on the mode of pseudorepeat interchange and loss. In the presence of micelles, the pseudorepeat region of SaS adopts an essentially continuous helix, whereas aS and beta-synuclein encounter a distinct helix break, indicating that a more homogeneous distribution of surfactant affinities in SaS prevented the formation of an extensive helix break in the micelle-bound state. By demonstrating the importance of the distribution of beta-sheet propensities and by revealing inhomogeneous aS surfactant affinities, the present study provides novel insights into two central themes of synuclein biology.

| S-EPMC2731582 | biostudies-literature

Alpha-Synuclein and Calpains Disrupt SNARE-Mediated Synaptic Vesicle Fusion During Manganese Exposure in SH-SY5Y Cells.

Project description:Synaptic vesicle fusion is mediated by an assembly of soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors (SNAREs), composed of syntaxin 1, soluble NSF-attachment protein (SNAP)-25, and synaptobrevin-2/VAMP-2. Previous studies have suggested that over-exposure to manganese (Mn) could disrupt synaptic vesicle fusion by influencing SNARE complex formation, both in vitro and in vivo. However, the mechanisms underlying this effect remain unclear. Here we employed calpeptin, an inhibitor of calpains, along with a lentivirus vector containing alpha-synuclein (?-Syn) shRNA, to examine whether specific SNAP-25 cleavage and the over-expression of ?-Syn disturbed the formation of the SNARE complex in SH-SY5Y cells. After cells were treated with Mn for 24 h, fragments of SNAP-25-N-terminal protein began to appear; however, this effect was reduced in the group of cells which were pre-treated with calpeptin. FM1-43-labeled synaptic vesicle fusion decreased with Mn treatment, which was consistent with the formation of SNARE complexes. The interaction of VAMP-2 and ?-Syn increased significantly in normal cells in response to 100 ?M Mn treatment, but decreased in LV-?-Syn shRNA cells treated with 100 ?M Mn; similar results were observed in terms of the formation of SNARE complexes and FM1-43-labeled synaptic vesicle fusion. Our data suggested that Mn treatment could increase [Ca2+]i, leading to abnormally excessive calpains activity, which disrupted the SNARE complex by cleaving SNAP-25. Our data also provided convincing evidence that Mn could induce the over-expression of ?-Syn; when combined with VAMP-2, ?-Syn prevented VAMP-2 from joining the SNARE complex cycle.

| S-EPMC6316740 | biostudies-literature

Phosphorylation at S87 is enhanced in synucleinopathies, inhibits alpha-synuclein oligomerization, and influences synuclein-membrane interactions.

Project description:Increasing evidence suggests that phosphorylation may play an important role in the oligomerization, fibrillogenesis, Lewy body (LB) formation, and neurotoxicity of alpha-synuclein (alpha-syn) in Parkinson disease. Herein we demonstrate that alpha-syn is phosphorylated at S87 in vivo and within LBs. The levels of S87-P are increased in brains of transgenic (TG) models of synucleinopathies and human brains from Alzheimer disease (AD), LB disease (LBD), and multiple system atrophy (MSA) patients. Using antibodies against phosphorylated alpha-syn (S129-P and S87-P), a significant amount of immunoreactivity was detected in the membrane in the LBD, MSA, and AD cases but not in normal controls. In brain homogenates from diseased human brains and TG animals, the majority of S87-P alpha-syn was detected in the membrane fractions. A battery of biophysical methods were used to dissect the effect of S87 phosphorylation on the structure, aggregation, and membrane-binding properties of monomeric alpha-syn. These studies demonstrated that phosphorylation at S87 expands the structure of alpha-syn, increases its conformational flexibility, and blocks its fibrillization in vitro. Furthermore, phosphorylation at S87, but not S129, results in significant reduction of alpha-syn binding to membranes. Together, our findings provide novel mechanistic insight into the role of phosphorylation at S87 and S129 in the pathogenesis of synucleinopathies and potential roles of phosphorylation in alpha-syn normal biology.

| S-EPMC2947449 | biostudies-literature

?-Synuclein assembles into higher-order multimers upon membrane binding to promote SNARE complex formation.

Project description:Physiologically, ?-synuclein chaperones soluble NSF attachment protein receptor (SNARE) complex assembly and may also perform other functions; pathologically, in contrast, ?-synuclein misfolds into neurotoxic aggregates that mediate neurodegeneration and propagate between neurons. In neurons, ?-synuclein exists in an equilibrium between cytosolic and membrane-bound states. Cytosolic ?-synuclein appears to be natively unfolded, whereas membrane-bound ?-synuclein adopts an ?-helical conformation. Although the majority of studies showed that cytosolic ?-synuclein is monomeric, it is unknown whether membrane-bound ?-synuclein is also monomeric, and whether chaperoning of SNARE complex assembly by ?-synuclein involves its cytosolic or membrane-bound state. Here, we show using chemical cross-linking and fluorescence resonance energy transfer (FRET) that ?-synuclein multimerizes into large homomeric complexes upon membrane binding. The FRET experiments indicated that the multimers of membrane-bound ?-synuclein exhibit defined intermolecular contacts, suggesting an ordered array. Moreover, we demonstrate that ?-synuclein promotes SNARE complex assembly at the presynaptic plasma membrane in its multimeric membrane-bound state, but not in its monomeric cytosolic state. Our data delineate a folding pathway for ?-synuclein that ranges from a monomeric, natively unfolded form in cytosol to a physiologically functional, multimeric form upon membrane binding, and show that only the latter but not the former acts as a SNARE complex chaperone at the presynaptic terminal, and may protect against neurodegeneration.

| S-EPMC4210039 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data