scholarly journals Synaptobrevin-2 dependent regulation of single synaptic vesicle endocytosis

2021 ◽  
pp. mbc.E21-04-0213
Author(s):  
Natali L. Chanaday ◽  
Ege T. Kavalali
Keyword(s):  
Synaptic Vesicle ◽  
Molecular Mechanism ◽  
Synaptic Vesicles ◽  
Dependent Manner ◽  
Multiple Systems ◽  
Receptor Proteins ◽  
Kinetics Of

Evidence from multiple systems indicates that vesicle SNARE ( Soluble NSF Attachment REceptor) proteins are involved in synaptic vesicle endocytosis, although their exact action at the level of single vesicles are unknown. Here we interrogate the role of the main synaptic vesicle SNARE mediating fusion, synaptobrevin-2 (also called VAMP2), in modulation of single synaptic vesicle retrieval. We report that in the absence of synaptobrevin-2 fast and slow modes of single synaptic vesicle retrieval are impaired, indicating a role of the SNARE machinery in coupling exocytosis to endocytosis of single synaptic vesicles. Ultrafast endocytosis was impervious to changes in the levels of synaptobrevin-2, pointing to a separate molecular mechanism underlying this type of recycling. Taken together with earlier studies suggesting a role of synaptobrevin-2 in endocytosis, these results indicate that the machinery for fast synchronous release couples fusion to retrieval and regulates the kinetics of endocytosis in Ca2+ dependent manner.

scholarly journals Counting the Number of Glutamate Molecules in Single Synaptic Vesicles

2019 ◽  
Author(s):  
Yuanmo Wang ◽  
Hoda fathali ◽  
devesh mishra ◽  
Thomas Olsson ◽  
Jacqueline Keighron ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
High Speed ◽  
Glutamate Release ◽  
Dependent Manner ◽  
Excitatory Neurotransmitter ◽  
Quantitative Measurements ◽  
Sensor Technique ◽  
Drug Treatments ◽  
Analytical Tools

<div><p>Analytical tools for direct quantitative measurements of glutamate, the principal excitatory neurotransmitter in brain, are lacking. Here, we introduce a new enzyme-based amperometric sensor technique for direct counting of the number of glutamate molecules stored inside single synaptic vesicles. An ultra-fast enzyme-based glutamate sensor is placed into a solution of isolated synaptic vesicles, which stochastically rupture at the sensor surface in a potential dependent manner by applying a constant negative potential. High-speed (10 kHz) amperometry is used to record sub-millisecond current spikes, which represent glutamate release from single vesicles that burst open. Glutamate quantification is achieved by a calibration curve that is based on measurements of glutamate release from vesicles pre-filled with various concentrations of glutamate. Our measurements show that a single synaptic vesicle encapsulates about 8000 glutamate molecules, which is comparable to the measured exocytotic quantal glutamate release in the nucleus accumbens of mouse brain tissue. Hence, this new methodology introduces the means to quantify ultra-small amounts of glutamate and to study synaptic vesicle physiology, pathogenesis and drug treatments for neuronal disorders where glutamate is involved.</p></div>

scholarly journals Dual pools of actin at presynaptic terminals

2012 ◽  
Vol 107 (12) ◽  
pp. 3479-3492 ◽  
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.

The Role of Intermolecular Forces in the Mechanism of High-Elastic Deformation. I. The Molecular Mechanism and an Equation for the Kinetics of High Elastic Deformation

1951 ◽  
Vol 24 (2) ◽  
pp. 336-343
Author(s):  
B. A. Dogadkin ◽  
G. M. Bartenev ◽  
M. M. Reznikovskii˘
Keyword(s):  
Molecular Structure ◽  
Molecular Mechanism ◽  
Elastic Deformation ◽  
Approximate Equation ◽  
Intermolecular Forces ◽  
Joint Application ◽  
Balanced Configurations ◽  
Kinetics Of ◽  
Constant Deformation

Abstract 1. The molecular mechanism of the relaxation of deformation of high-elastic polymers has been studied. 2. It is shown that the slow relaxation, which is typical of high-elastic polymers, may be best explained as a restoration process, which either partial or complete (depending on the degree of development of side chains in the molecular structure formed by the main valence chains) of the balanced configurations of the molecular chains. 3. It is shown that the rate of the relaxation process in this case is determined by the molecular activity of the particular polymer. 4. An approximate equation for the kinetics of high-elastic deformation which expresses qualitatively the mechanical properties of high-elastic polymers is proposed. 5. Hypotheses concerning the relation between the time of relaxation and the unbalanced stress are advanced. Equation (2) is derived as characteristic of this relation. 6. It is shown that the joint application of Equations (1) and (2) makes it possible to describe qualitatively the relaxation of stress at constant deformation.

scholarly journals The dual role of chloride in synaptic vesicle glutamate transport

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Roger Chang ◽  
Jacob Eriksen ◽  
Robert H Edwards
Keyword(s):  
Synaptic Vesicle ◽  
Indirect Effects ◽  
Synaptic Vesicles ◽  
Transmembrane Domain ◽  
Dose Dependence ◽  
Direct Effects ◽  
Allosteric Activation ◽  
Vesicular Glutamate Transporters ◽  
Cl Conductance

The transport of glutamate into synaptic vesicles exhibits an unusual form of regulation by Cl- as well as an associated Cl- conductance. To distinguish direct effects of Cl- on the transporter from indirect effects via the driving force Δψ, we used whole endosome recording and report the first currents due to glutamate flux by the vesicular glutamate transporters (VGLUTs). Chloride allosterically activates the VGLUTs from both sides of the membrane, and we find that neutralization of an arginine in transmembrane domain four suffices for the lumenal activation. The dose dependence suggests that Cl- permeates through a channel and glutamate through a transporter. Competition between the anions nonetheless indicates that they use a similar permeation pathway. By controlling both ionic gradients and Δψ, endosome recording isolates different steps in the process of synaptic vesicle filling, suggesting distinct roles for Cl- in both allosteric activation and permeation.

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 (&gt;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.

The kinetics of exsheathment of infective nematode larvae is disturbed in the presence of a tannin-rich plant extract (sainfoin) both in vitro and in vivo

Parasitology ◽  
2007 ◽  
Vol 134 (9) ◽  
pp. 1253-1262 ◽  
Author(s):  
S. BRUNET ◽  
J. AUFRERE ◽  
F. El BABILI ◽  
I. FOURASTE ◽  
H. HOSTE
Keyword(s):  
Parasite Species ◽  
Gastrointestinal Nematodes ◽  
Dependent Manner ◽  
Early Step ◽  
Nematode Larvae ◽  
Kinetics Of ◽  
Dose Dependent

SUMMARYThe mode of action of bioactive plants on gastrointestinal nematodes remains obscure. Previous in vitro studies showed that exsheathment was significantly disturbed after contact with tannin-rich extracts. However, the role of important factors (extract concentration, parasite species) has not been assessed and no information is available on the occurrence in vivo. These questions represent the objectives of this study. The model incorporated the parasites Haemonchus contortus and Trichostrongylus colubriformis with sainfoin as the bioactive plant. A set of in vitro assays was performed, measuring the changes observed, after 3 h of contact with increasing concentrations of sainfoin, on the rate of artificial exsheathment. The results indicated that sainfoin extracts interfered with exsheathment in a dose-dependent manner and the process overall was similar for both nematodes. The restoration of control values observed after adding PEG to extracts confirms a major role for tannins. A second study was performed in vivo on rumen-cannulated sheep fed with different proportions of sainfoin in the diet to verify these in vitro results. The consumption of a higher proportion of sainfoin was indeed associated with significant delays in Haemonchus exsheathment. Overall, the results confirmed that interference with the early step of nematode infection might be one of the modes of action that contributes to the anthelmintic properties of tanniniferous plants.

Role of calcium in secretory and metabolic effects of substrates in the gastric mucosa

1986 ◽  
Vol 251 (2) ◽  
pp. G161-G168
Author(s):  
J. Chacin ◽  
P. Cardenas ◽  
P. Lobo ◽  
O. Subero
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Glucose Oxidation ◽  
Metabolic Effects ◽  
Secretory Process ◽  
Dependent Manner ◽  
Metabolic Substrates ◽  
External Potassium ◽  
Kinetics Of

The role of extracellular Ca2+ in the effects and oxidation of metabolic substrates was investigated in the isolated toad gastric mucosa. In the presence of lipoate, the stimulating effect of 10 mM glucose on spontaneous acid secretion was significantly reduced by 76% in Ca2+-free solutions. The inhibition was overcome by addition of 5 mM Ca2+. The increment in respiration induced by glucose was also blocked in the absence of external Ca2+. The effect of 10 mM pyruvate on acid secretion was inhibited by 37% in Ca2+-free solutions. The secretory responses induced by 10 mM butyrate and 10 mM octanoate were not significantly affected by Ca2+-free solutions. The rates of oxidation of [14C]-glucose and [14C]pyruvate were significantly reduced by incubating in Ca2+-free solutions containing 0.1 mM of EGTA. When O2 uptake and glucose oxidation were measured simultaneously in the same preparation, the increment in the rate of glucose oxidation accounted for by 43% of the total increase of respiration observed in the presence of Ca2+. The rates of oxidation of [14C]butyrate and [14C]acetate were not significantly affected by Ca2+-free solutions. The rate of oxidation of [14C]glucose exhibited saturation kinetics versus concentration and was lower in the absence of external Ca2+ under a range of glucose concentrations. Similar results were observed when the experiments were performed in the absence of external potassium to block the acid secretory process. Ca2+ stimulated the rate of glucose oxidation in a dose-dependent manner. The kinetics of 45Ca2+ efflux and 45Ca2+ uptake were not significantly affected by glucose and butyrate.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The docking of synaptic vesicles on the presynaptic membrane induced by α-synuclein is modulated by lipid composition

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wing K. Man ◽  
Bogachan Tahirbegi ◽  
Michail D. Vrettas ◽  
Swapan Preet ◽  
Liming Ying ◽  
...  
Keyword(s):  
Lipid Composition ◽  
Synaptic Vesicles ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Disordered Protein ◽  
Conformational Properties ◽  
Small Unilamellar Vesicles ◽  
Presynaptic Plasma Membrane

Abstractα-Synuclein (αS) is a presynaptic disordered protein whose aberrant aggregation is associated with Parkinson’s disease. The functional role of αS is still debated, although it has been involved in the regulation of neurotransmitter release via the interaction with synaptic vesicles (SVs). We report here a detailed characterisation of the conformational properties of αS bound to the inner and outer leaflets of the presynaptic plasma membrane (PM), using small unilamellar vesicles. Our results suggest that αS preferentially binds the inner PM leaflet. On the basis of these studies we characterise in vitro a mechanism by which αS stabilises, in a concentration-dependent manner, the docking of SVs on the PM by establishing a dynamic link between the two membranes. The study then provides evidence that changes in the lipid composition of the PM, typically associated with neurodegenerative diseases, alter the modes of binding of αS, specifically in a segment of the sequence overlapping with the non-amyloid component region. Taken together, these results reveal how lipid composition modulates the interaction of αS with the PM and underlie its functional and pathological behaviours in vitro.

scholarly journals Synaptic-like microvesicles, synaptic vesicle counterparts in endocrine cells, are involved in a novel regulatory mechanism for the synthesis and secretion of hormones

2000 ◽  
Vol 203 (1) ◽  
pp. 117-125 ◽  
Author(s):  
Y. Moriyama ◽  
M. Hayashi ◽  
H. Yamada ◽  
S. Yatsushiro ◽  
S. Ishio ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Pineal Gland ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Endocrine Cells ◽  
Regulatory Mechanism ◽  
Vesicular Transporter ◽  
Functional Equivalent ◽  
Acidic Organelles

Microvesicles in endocrine cells are the morphological and functional equivalent of neuronal synaptic vesicles. Microvesicles accumulate various neurotransmitters through a transmitter-specific vesicular transporter energized by vacuolar H(+)-ATPase. We found that mammalian pinealocytes, endocrine cells that synthesize and secrete melatonin, accumulate l-glutamate in their microvesicles and secrete it through exocytosis. Pinealocytes use l-glutamate as either a paracrine- or autocrine-like chemical transmitter in a receptor-mediated manner, resulting in inhibition of melatonin synthesis. In this article, we briefly describe the overall features of the microvesicle-mediated signal-transduction mechanism in the pineal gland and discuss the important role of acidic organelles in a novel regulatory mechanism for hormonal synthesis and secretion.

scholarly journals Counting the Number of Glutamate Molecules in Single Synaptic Vesicles

2019 ◽  
Author(s):  
Yuanmo Wang ◽  
Hoda fathali ◽  
devesh mishra ◽  
Thomas Olsson ◽  
Jacqueline Keighron ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
High Speed ◽  
Glutamate Release ◽  
Dependent Manner ◽  
Excitatory Neurotransmitter ◽  
Quantitative Measurements ◽  
Sensor Technique ◽  
Drug Treatments ◽  
Analytical Tools

<div><p>Analytical tools for direct quantitative measurements of glutamate, the principal excitatory neurotransmitter in brain, are lacking. Here, we introduce a new enzyme-based amperometric sensor technique for direct counting of the number of glutamate molecules stored inside single synaptic vesicles. An ultra-fast enzyme-based glutamate sensor is placed into a solution of isolated synaptic vesicles, which stochastically rupture at the sensor surface in a potential dependent manner by applying a constant negative potential. High-speed (10 kHz) amperometry is used to record sub-millisecond current spikes, which represent glutamate release from single vesicles that burst open. Glutamate quantification is achieved by a calibration curve that is based on measurements of glutamate release from vesicles pre-filled with various concentrations of glutamate. Our measurements show that a single synaptic vesicle encapsulates about 8000 glutamate molecules, which is comparable to the measured exocytotic quantal glutamate release in the nucleus accumbens of mouse brain tissue. Hence, this new methodology introduces the means to quantify ultra-small amounts of glutamate and to study synaptic vesicle physiology, pathogenesis and drug treatments for neuronal disorders where glutamate is involved.</p></div>

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