In vivo evidence of lower synaptic vesicle density in schizophrenia

Background: Patients with temporal lobe epilepsy (TLE) usually suffer from cognitive deficits and recurrent seizures. Brivaracetam (BRV) is a novel anti-epileptic drug (AEDs) recently used for the treatment of partial seizures with or without secondary generalization. Different from other AEDs, BRV has some favorable properties on synaptic plasticity. However, the underlying mechanisms remain elusive. Objective: The aim of this study was to explore the neuroprotective mechanism of BRV on synaptic plasticity in experimental TLE rats. Methods: The effect of chronic treatment with BRV (10 mg/kg) was assessed on Pilocarpine induced TLE model through measurement of the field excitatory postsynaptic potentials (fEPSPs) in vivo. Differentially expressed synaptic vesicle protein 2A (SV2A) were identified with immunoblot. Then, fast phosphorylation of synaptosomal-associated protein 25 (SNAP-25) during long-term potentiation (LTP) induction was performed to investigate the potential roles of BRV on synaptic plasticity in the TLE model. Results: An increased level of SV2A accompanied by a depressed LTP in the hippocampus was shown in epileptic rats. Furthermore, BRV treatment continued for more than 30 days improved the over-expression of SV2A and reversed the synaptic dysfunction in epileptic rats. Additionally, BRV treatment alleviates the abnormal SNAP-25 phosphorylation at Ser187 during LTP induction in epileptic ones, which is relevant to the modulation of synaptic vesicles exocytosis and voltagegated calcium channels. Conclusion: BRV treatment ameliorated the over-expression of SV2A in the hippocampus and rescued the synaptic dysfunction in epileptic rats. These results identify the neuroprotective effect of BRV on TLE model.

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Dual pools of actin at presynaptic terminals

Journal of Neurophysiology ◽

10.1152/jn.00789.2011 ◽

2012 ◽

Vol 107 (12) ◽

pp. 3479-3492 ◽

Cited By ~ 22

Author(s):

Adam Bleckert ◽

Huzefa Photowala ◽

Simon Alford

Keyword(s):

Synaptic Transmission ◽

Synaptic Vesicle ◽

Synaptic Vesicles ◽

Repetitive Stimulation ◽

Filamentous Actin ◽

Cortical Actin ◽

Vesicle Recycling ◽

Latrunculin A ◽

Kinetics Of

We investigated actin's function in vesicle recycling and exocytosis at lamprey synapses and show that FM1-43 puncta and phalloidin-labeled filamentous actin (F-actin) structures are colocalized, yet recycling vesicles are not contained within F-actin clusters. Additionally, phalloidin also labels a plasma membrane-associated cortical actin. Injection of fluorescent G-actin revealed activity-independent dynamic actin incorporation into presynaptic synaptic vesicle clusters but not into cortical actin. Latrunculin-A, which sequesters G-actin, dispersed vesicle-associated actin structures and prevented subsequent labeled G-actin and phalloidin accumulation at presynaptic puncta, yet cortical phalloidin labeling persisted. Dispersal of presynaptic F-actin structures by latrunculin-A did not disrupt vesicle clustering or recycling or alter the amplitude or kinetics of excitatory postsynaptic currents (EPSCs). However, it slightly enhanced release during repetitive stimulation. While dispersal of presynaptic actin puncta with latrunculin-A failed to disperse synaptic vesicles or inhibit synaptic transmission, presynaptic phalloidin injection blocked exocytosis and reduced endocytosis measured by action potential-evoked FM1-43 staining. Furthermore, phalloidin stabilization of only cortical actin following pretreatment with latrunculin-A was sufficient to inhibit synaptic transmission. Conversely, treatment of axons with jasplakinolide, which induces F-actin accumulation but disrupts F-actin structures in vivo, resulted in increased synaptic transmission accompanied by a loss of phalloidin labeling of cortical actin but no loss of actin labeling within vesicle clusters. Marked synaptic deficits seen with phalloidin stabilization of cortical F-actin, in contrast to the minimal effects of disruption of a synaptic vesicle-associated F-actin, led us to conclude that two structurally and functionally distinct pools of actin exist at presynaptic sites.

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Poststimulation Increase of Synaptic Vesicle Number in the Preganglionic Nerve Terminals of the Cat Sympathetic Ganglion In Vivo

Cellular and Molecular Basis of Synaptic Transmission ◽

10.1007/978-3-642-73172-3_4 ◽

1988 ◽

pp. 73-82 ◽

Cited By ~ 2

Author(s):

Tomoko Kadota ◽

Ken Kadota ◽

Hozumi Tatsuoka ◽

Muneaki Mizote ◽

Tomoichiro Yamaai

Keyword(s):

Synaptic Vesicle ◽

Sympathetic Ganglion ◽

Nerve Terminals

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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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De novo disease-associated mutations in KIF1A dominant negatively inhibit axonal transport of synaptic vesicle precursors

10.1101/2021.07.22.453457 ◽

2021 ◽

Author(s):

Yuzu Anazawa ◽

Tomoki Kita ◽

Kumiko Hayashi ◽

Shinsuke Niwa

Keyword(s):

Synaptic Vesicle ◽

Axonal Transport ◽

De Novo ◽

Molecular Motor ◽

Model Systems ◽

In Vitro Assays ◽

In Vivo Model ◽

Wild Type

KIF1A is a kinesin superfamily molecular motor that transports synaptic vesicle precursors in axons. Mutations in Kif1a lead to a group of neuronal diseases called KIF1A-associated neuronal disorder (KAND). KIF1A forms a homodimer and KAND mutations are mostly de novo and autosomal dominant; however, it is not known whether the function of wild-type KIF1A is inhibited by disease-associated KIF1A. No reliable in vivo model systems to analyze the molecular and cellular biology of KAND have been developed; therefore, here, we established Caenorhabditis elegans models for KAND using CRISPR/cas9 technology and analyzed defects in axonal transport. In the C. elegans models, heterozygotes and homozygotes exhibited reduced axonal transport phenotypes. In addition, we developed in vitro assays to analyze the motility of single heterodimers composed of wild-type KIF1A and disease-associated KIF1A. Disease-associated KIF1A significantly inhibited the motility of wild-type KIF1A when heterodimers were formed. These data indicate the molecular mechanism underlying the dominant nature of de novo KAND mutations.

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Snca-GFP knock-in mice reflect patterns of endogenous expression and pathological seeding

10.1101/2020.05.05.077321 ◽

2020 ◽

Author(s):

Anna Caputo ◽

Yuling Liang ◽

Tobias D. Raabe ◽

Angela Lo ◽

Mian Horvath ◽

...

Keyword(s):

Mouse Model ◽

Fusion Protein ◽

Synaptic Vesicle ◽

Alpha Synuclein ◽

Peripheral Tissues ◽

Endogenous Expression ◽

Sequence Of Events ◽

Gfp Fusion Protein

AbstractAlpha-synuclein (aSyn) participates in synaptic vesicle trafficking and synaptic transmission, but its misfolding is also strongly implicated in Parkinson’s disease (PD) and other neurodegenerative disorders known as synucleinopathies where misfolded aSyn accumulates in different regions of the central and peripheral nervous systems. Although increased aSyn expression levels or altered aggregation propensities likely underlie familial PD with SNCA amplification or mutations, the majority of synucleinopathies arise sporadically, indicating that disease can develop under normal levels of wildtype aSyn. We report here the development and characterization of a mouse line expressing an aSyn-GFP fusion protein under the control of native Snca regulatory elements. Regional and subcellular localization of the aSyn-GFP fusion protein in brains and peripheral tissues of knock-in (KI) mice are indistinguishable from that of wildtype littermates. Importantly, similar to wildtype aSyn, aSyn-GFP disperses from synaptic vesicles upon membrane depolarization, indicating that the tag does not alter normal aSyn dynamics at synapses. In addition, intracerebral injection of aSyn pre-formed fibrils into KI mice induced the formation of aSyn-GFP inclusions with a distribution pattern similar to that observed in wildtype mice, albeit with attenuated kinetics due to the GFP tag. We anticipate that this new mouse model will facilitate in vitro and in vivo studies requiring in situ detection of endogenous aSyn, therefore providing new insights into aSyn function in health and disease.Significance StatementAlpha-synuclein (aSyn) participates in synaptic vesicle function and represents a major component of the Lewy pathology found in Parkinson’s and related neurodegenerative diseases. The function of aSyn and the sequence of events leading to its aggregation and neurotoxicity are not fully understood. Here we present a new mouse model in which Enhanced Green Fluorescence Protein (GFP) has been knocked-in at the C-terminal of the Snca gene. The resulting fusion protein shows identical expression and localization to that of wildtype animals, is functional, and is incorporated into pathological aggregates in vitro and in vivo. This new tool allows for monitoring aSyn under a variety of physiological and pathological conditions, and may uncover additional insights into its function and dysfunction.

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α-Synuclein-112 impairs synaptic vesicle recycling consistent with its enhanced membrane binding properties

10.1101/2020.04.03.024125 ◽

2020 ◽

Author(s):

Lindsey G. Soll ◽

Julia N. Eisen ◽

Karina J. Vargas ◽

Audrey T. Medeiros ◽

Katherine M. Hammar ◽

...

Keyword(s):

Synaptic Vesicle ◽

Lewy Bodies ◽

Detailed Examination ◽

Biochemical Properties ◽

Synaptic Membranes ◽

Synaptic Vesicle Recycling ◽

Splice Isoforms ◽

Vesicle Recycling

ABSTRACTSynucleinopathies are neurological disorders associated with α-synuclein overexpression and aggregation. While it is well established that overexpression of wild type α-synuclein (α-syn-140) leads to cellular toxicity and neurodegeneration, much less is known about other naturally occurring α-synuclein splice isoforms. In this study we provide the first detailed examination of the synaptic effects caused by one of these splice isoforms, α-synuclein-112 (α-syn-112). α-Syn-112 is produced by an in-frame excision of exon 5, resulting in deletion of amino acids 103-130 in the C-terminal region. α-Syn-112 is upregulated in the substantia nigra, frontal cortex, and cerebellum of parkinsonian brains and is correlated with susceptibility to sporadic Parkinson’s disease (PD), dementia with Lewy bodies (DLB) and multiple systems atrophy (MSA). We report here that α-syn-112 binds strongly to anionic phospholipids when presented in highly-curved liposomes, similar to α-syn-140. However, α-syn-112 bound significantly stronger to all phospholipids tested, including the phosphoinositides. α-Syn-112 also dimerized and trimerized on isolated synaptic membranes, while α-syn-140 remained largely monomeric. When introduced acutely to lamprey synapses, α-syn-112 robustly inhibited synaptic vesicle recycling. Interestingly, α-syn-112 produced effects on the plasma membrane and clathrin-mediated synaptic vesicle endocytosis that were phenotypically intermediate between those caused by monomeric and dimeric α-syn-140. These findings indicate that α-syn-112 exhibits enhanced phospholipid binding and oligomerization in vitro and consequently interferes with synaptic vesicle recycling in vivo in ways that are consistent with its biochemical properties. This study provides additional evidence suggesting that impaired vesicle endocytosis is a cellular target of excess α-synuclein and advances our understanding of potential mechanisms underlying disease pathogenesis in the synucleinopathies.

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Evaluating the In Vivo Specificity of [18F]UCB-H for the SV2A Protein, Compared with SV2B and SV2C in Rats Using microPET

Molecules ◽

10.3390/molecules24091705 ◽

2019 ◽

Vol 24 (9) ◽

pp. 1705 ◽

Cited By ~ 3

Author(s):

Maria Elisa Serrano ◽

Guillaume Becker ◽

Mohamed Ali Bahri ◽

Alain Seret ◽

Nathalie Mestdagh ◽

...

Keyword(s):

Synaptic Vesicle ◽

Brain Structures ◽

Input Function ◽

Population Based ◽

The Other ◽

Sprague Dawley ◽

Logan Plot ◽

Sprague Dawley Rats ◽

Inferior Colliculi

The synaptic vesicle protein 2 (SV2) is involved in synaptic vesicle trafficking. The SV2A isoform is the most studied and its implication in epilepsy therapy led to the development of the first SV2A PET radiotracer [18F]UCB-H. The objective of this study was to evaluate in vivo, using microPET in rats, the specificity of [18F]UCB-H for SV2 isoform A in comparison with the other two isoforms (B and C) through a blocking assay. Twenty Sprague Dawley rats were pre-treated either with the vehicle, or with specific competitors against SV2A (levetiracetam), SV2B (UCB5203) and SV2C (UCB0949). The distribution volume (Vt, Logan plot, t* 15 min) was obtained with a population-based input function. The Vt analysis for the entire brain showed statistically significant differences between the levetiracetam group and the other groups (p < 0.001), but also between the vehicle and the SV2B group (p < 0.05). An in-depth Vt analysis conducted for eight relevant brain structures confirmed the statistically significant differences between the levetiracetam group and the other groups (p < 0.001) and highlighted the superior and the inferior colliculi along with the cortex as regions also displaying statistically significant differences between the vehicle and SV2B groups (p < 0.05). These results emphasize the in vivo specificity of [18F]UCB-H for SV2A against SV2B and SV2C, confirming that [18F]UCB-H is a suitable radiotracer for in vivo imaging of the SV2A proteins with PET.

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A dual role for α-synuclein in facilitation and depression of dopamine release from substantia nigra neurons in vivo

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2013652117 ◽

2020 ◽

Vol 117 (51) ◽

pp. 32701-32710

Author(s):

Mahalakshmi Somayaji ◽

Stefano Cataldi ◽

Se Joon Choi ◽

Robert H. Edwards ◽

Eugene V. Mosharov ◽

...

Keyword(s):

Substantia Nigra ◽

Action Potential ◽

Synaptic Vesicle ◽

Neuronal Activity ◽

Dopamine Release ◽

Short Intervals ◽

Presynaptic Plasticity ◽

Presynaptic Calcium ◽

Synaptic Vesicle Fusion

α-Synuclein is expressed at high levels at presynaptic terminals, but defining its role in the regulation of neurotransmission under physiologically relevant conditions has proven elusive. We report that, in vivo, α-synuclein is responsible for the facilitation of dopamine release triggered by action potential bursts separated by short intervals (seconds) and a depression of release with longer intervals between bursts (minutes). These forms of presynaptic plasticity appear to be independent of the presence of β- and γ-synucleins or effects on presynaptic calcium and are consistent with a role for synucleins in the enhancement of synaptic vesicle fusion and turnover. These results indicate that the presynaptic effects of α-synuclein depend on specific patterns of neuronal activity.

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