Expression of synaptotagmin in Drosophila reveals transport and localization of synaptic vesicles to the synapse

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1077-1088 ◽  
Author(s):  
J.T. Littleton ◽  
H.J. Bellen ◽  
M.S. Perin
Keyword(s):  
Nervous System ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Synapse Formation ◽  
Neuromuscular Junctions ◽  
Synaptic Contact ◽  
Immunocytochemical Staining ◽  
Intense Staining ◽  
General Role ◽  
Contact Sites

Synaptotagmin is a synaptic vesicle-specific integral membrane protein that has been suggested to play a key role in synaptic vesicle docking and fusion. By monitoring Synaptotagmin's cellular and subcellular distribution during development, it is possible to study synaptic vesicle localization and transport, and synapse formation. We have initiated the study of Synaptotagmin's expression during Drosophila neurogenesis in order to follow synaptic vesicle movement prior to and during synapse formation, as well as to localize synaptic sites in Drosophila. In situ hybridizations to whole-mount embryos show that synaptotagmin (syt) message is present in the cell bodies of all peripheral nervous system neurons and many, if not all, central nervous system neurons during neurite outgrowth and synapse formation, and in mature neurons. Immunocytochemical staining with antisera specific to Synaptotagmin indicates that the protein is present at all stages of the Drosophila life cycle following germ band retraction. In embryos, Synaptotagmin is only transiently localized to the cell body of neurons and is transported rapidly along axons during axonogenesis. After synapse formation, Synaptotagmin accumulates in a punctate pattern at all identifiable synaptic contact sites, suggesting a general role for Synaptotagmin in synapse function. In embryos and larvae, the most intense staining is found along two broad longitudinal tracts on the dorsal side of the ventral nerve cord and the brain, and at neuromuscular junctions in the periphery. In the adult head, Synaptotagmin localizes the discrete regions of the neurophil where synapses are predicted to occur. These data indicate that synaptic vesicles are present in axons before synapse formation, and become restricted to synaptic contact sites after synapses are formed. Since a similar expression pattern of Synaptotagmin has been reported in mammals, we propose that the function of Synaptotagmin and the mechanisms governing localization of the synaptic vesicle before and after synapse formation are conserved in invertebrate and vertebrate species. The ability to mark synapses in Drosophila should facilitate the study of synapse formation and function, providing a new tool to dissect the molecular mechanisms underlying these processes.

scholarly journals BDNF mobilizes synaptic vesicles and enhances synapse formation by disrupting cadherin–β-catenin interactions

2006 ◽  
Vol 174 (2) ◽  
pp. 289-299 ◽  
Author(s):  
Shernaz X. Bamji ◽  
Beatriz Rico ◽  
Nikole Kimes ◽  
Louis F. Reichardt
Keyword(s):  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Synapse Formation ◽  
Time Lapse ◽  
Synapse Density ◽  
Vesicle Mobility ◽  
Small Clusters ◽  
Vertebrate Central Nervous System

Neurons of the vertebrate central nervous system have the capacity to modify synapse number, morphology, and efficacy in response to activity. Some of these functions can be attributed to activity-induced synthesis and secretion of the neurotrophin brain-derived neurotrophic factor (BDNF); however, the molecular mechanisms by which BDNF mediates these events are still not well understood. Using time-lapse confocal analysis, we show that BDNF mobilizes synaptic vesicles at existing synapses, resulting in small clusters of synaptic vesicles “splitting” away from synaptic sites. We demonstrate that BDNF's ability to mobilize synaptic vesicle clusters depends on the dissociation of cadherin–β-catenin adhesion complexes that occurs after tyrosine phosphorylation of β-catenin. Artificially maintaining cadherin–β-catenin complexes in the presence of BDNF abolishes the BDNF-mediated enhancement of synaptic vesicle mobility, as well as the longer-term BDNF-mediated increase in synapse number. Together, this data demonstrates that the disruption of cadherin–β-catenin complexes is an important molecular event through which BDNF increases synapse density in cultured hippocampal neurons.

scholarly journals μ2 adaptin facilitates but is not essential for synaptic vesicle recycling in Caenorhabditis elegans

2008 ◽  
Vol 183 (5) ◽  
pp. 881-892 ◽  
Author(s):  
Mingyu Gu ◽  
Kim Schuske ◽  
Shigeki Watanabe ◽  
Qiang Liu ◽  
Paul Baum ◽  
...  
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Evoked Responses ◽  
Nematode Caenorhabditis Elegans ◽  
Synaptic Vesicle Recycling ◽  
Specific Loss ◽  
Vesicle Recycling ◽  
Cargo Proteins

Synaptic vesicles must be recycled to sustain neurotransmission, in large part via clathrin-mediated endocytosis. Clathrin is recruited to endocytic sites on the plasma membrane by the AP2 adaptor complex. The medium subunit (μ2) of AP2 binds to cargo proteins and phosphatidylinositol-4,5-bisphosphate on the cell surface. Here, we characterize the apm-2 gene (also called dpy-23), which encodes the only μ2 subunit in the nematode Caenorhabditis elegans. APM-2 is highly expressed in the nervous system and is localized to synapses; yet specific loss of APM-2 in neurons does not affect locomotion. In apm-2 mutants, clathrin is mislocalized at synapses, and synaptic vesicle numbers and evoked responses are reduced to 60 and 65%, respectively. Collectively, these data suggest AP2 μ2 facilitates but is not essential for synaptic vesicle recycling.

scholarly journals BETA- AND GAMMA-SYNUCLEINS MODULATE SYNAPTIC VESICLE-BINDING OF ALPHA-SYNUCLEIN

2020 ◽  
Author(s):  
Kathryn E. Carnazza ◽  
Lauren Komer ◽  
André Pineda ◽  
Yoonmi Na ◽  
Trudy Ramlall ◽  
...  
Keyword(s):  
Nervous System ◽  
Synaptic Vesicle ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Direct Interaction ◽  
Alpha Synuclein ◽  
Snare Complex ◽  
Complex Assembly ◽  
Mutual Compensation ◽  
Conflicting Evidence

SUMMARYα-Synuclein (αSyn), β-synuclein (βSyn), and γ-synuclein (γSyn) are abundantly expressed in the vertebrate nervous system. αSyn functions in neurotransmitter release via binding to and clustering synaptic vesicles and chaperoning of SNARE-complex assembly. The functions of βSyn and γSyn are unknown. Functional redundancy of the three synucleins and mutual compensation when one synuclein is deleted have been proposed, but with conflicting evidence. Here, we demonstrate that βSyn and γSyn have a reduced affinity towards membranes compared to αSyn, and that direct interaction of βSyn or γSyn with αSyn results in reduced membrane binding of αSyn. Our data suggest that all three synucleins affect synapse function, but only αSyn mediates the downstream function of vesicle clustering and SNARE-complex assembly, while βSyn and γSyn modulate the activity of αSyn through regulating its binding to synaptic vesicles.

scholarly journals Synaptic Vesicles Having Large Contact Areas with the Presynaptic Membrane are Preferentially Hemifused at Active Zones of Frog Neuromuscular Junctions Fixed during Synaptic Activity

2019 ◽  
Vol 20 (11) ◽  
pp. 2692
Author(s):  
Jae Hoon Jung
Keyword(s):  
Synaptic Vesicles ◽  
Neuromuscular Junctions ◽  
Synaptic Activity ◽  
Membrane Thickness ◽  
Intermediate Step ◽  
Presynaptic Membrane ◽  
Vesicle Membrane ◽  
Contact Areas ◽  
Contact Sites ◽  
Active Zones

Synaptic vesicles dock on the presynaptic plasma membrane of axon terminals and become ready to fuse with the presynaptic membrane or primed. Fusion of the vesicle membrane and presynaptic membrane results in the formation of a pore between the membranes, through which the vesicle’s neurotransmitter is released into the synaptic cleft. A recent electron tomography study on frog neuromuscular junctions fixed at rest showed that there is no discernible gap between or merging of the membrane of docked synaptic vesicles with the presynaptic membrane, however, the extent of the contact area between the membrane of docked synaptic vesicles and the presynaptic membrane varies 10-fold with a normal distribution. The study also showed that when the neuromuscular junctions are fixed during repetitive electrical nerve stimulation, the portion of large contact areas in the distribution is reduced compared to the portion of small contact areas, suggesting that docked synaptic vesicles with the largest contact areas are greatly primed to fuse with the membrane. Furthermore, the finding of several hemifused synaptic vesicles among the docked vesicles was briefly reported. Here, the spatial relationship of 81 synaptic vesicles with the presynaptic membrane at active zones of the neuromuscular junctions fixed during stimulation is described in detail. For the most of the vesicles, the combined thickness of each of their contact sites was not different from the sum of the membrane thicknesses of the vesicle membrane and presynaptic membrane, similar to the docked vesicles at active zones of the resting neuromuscular junctions. However, the combined membrane thickness of a small portion of the vesicles was considerably less than the sum of the membrane thicknesses, indicating that the membranes at their contact sites were fixed in a state of hemifusion. Moreover, the hemifused vesicles were found to have large contact areas with the presynaptic membrane. These findings support the recently proposed hypothesis that, at frog neuromuscular junctions, docked synaptic vesicles with the largest contact areas are most primed for fusion with the presynaptic membrane, and that hemifusion is a fusion intermediate step of the vesicle membrane with the presynaptic membrane for synaptic transmission.

scholarly journals Tetanus Toxin and Botulinum Toxin A Utilize Unique Mechanisms To Enter Neurons of the Central Nervous System

2012 ◽  
Vol 80 (5) ◽  
pp. 1662-1669 ◽  
Author(s):  
Faith C. Blum ◽  
Chen Chen ◽  
Abby R. Kroken ◽  
Joseph T. Barbieri
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Botulinum Toxin A ◽  
Specific Protein ◽  
Spastic Paralysis ◽  
Vesicle Cycling ◽  
Protein Receptor ◽  
Cns Neurons

ABSTRACTBotulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) are the most toxic proteins for humans. While BoNTs cause flaccid paralysis, TeNT causes spastic paralysis. Characterized BoNT serotypes enter neurons upon binding dual receptors, a ganglioside and a neuron-specific protein, either synaptic vesicle protein 2 (SV2) or synaptotagmin, while TeNT enters upon binding gangliosides as dual receptors. Recently, TeNT was reported to enter central nervous system (CNS) neurons upon synaptic vesicle cycling that was mediated by the direct binding to SV2, implying that TeNT and BoNT utilize common mechanisms to enter CNS neurons. This prompted an assessment of TeNT entry into CNS neurons, using the prototypic BoNT serotype A as a reference for SV2-mediated entry into synaptic vesicles, analyzing the heavy-chain receptor binding domain (HCR) of each toxin. Synaptic vesicle cycling stimulated the entry of HCR/A into neurons, while HCR/T entered neurons with similar levels of efficiency in depolarized and nondepolarized neurons. ImageJ analysis identified two populations of cell-associated HCR/T in synaptic vesicle cycling neurons, a major population which segregated from HCR/A and a minor population which colocalized with HCR/A. HCR/T did not inhibit HCR/A entry into neurons in competition experiments and did not bind SV2, the protein receptor for BoNT/A. Intoxication experiments showed that TeNT efficiently cleaved VAMP2 in depolarized neurons and neurons blocked for synaptic vesicle cycling. These experiments demonstrate that TeNT enters neurons by two pathways, one independent of stimulated synaptic vesicle cycling and one by synaptic vesicles independent of SV2, showing that TeNT and BoNT/A enter neurons by unique mechanisms.

scholarly journals Synapses are regulated by the cytoplasmic tyrosine kinase Fer in a pathway mediated by p120catenin, Fer, SHP-2, and β-catenin

2008 ◽  
Vol 183 (5) ◽  
pp. 893-908 ◽  
Author(s):  
Seung-Hye Lee ◽  
I.-Feng Peng ◽  
Yu Gie Ng ◽  
Masahiro Yanagisawa ◽  
Shernaz X. Bamji ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Tyrosine Kinase ◽  
Synaptic Vesicle ◽  
Tyrosine Phosphorylation ◽  
Protein Phosphatase ◽  
Synaptic Vesicles ◽  
Synapse Formation ◽  
Excitatory Synapse ◽  
Synaptic Development ◽  
And Function

Localization of presynaptic components to synaptic sites is critical for hippocampal synapse formation. Cell adhesion–regulated signaling is important for synaptic development and function, but little is known about differentiation of the presynaptic compartment. In this study, we describe a pathway that promotes presynaptic development involving p120catenin (p120ctn), the cytoplasmic tyrosine kinase Fer, the protein phosphatase SHP-2, and β-catenin. Presynaptic Fer depletion prevents localization of active zone constituents and synaptic vesicles and inhibits excitatory synapse formation and synaptic transmission. Depletion of p120ctn or SHP-2 similarly disrupts synaptic vesicle localization with active SHP-2, restoring synapse formation in the absence of Fer. Fer or SHP-2 depletion results in elevated tyrosine phosphorylation of β-catenin. β-Catenin overexpression restores normal synaptic vesicle localization in the absence of Fer or SHP-2. Our results indicate that a presynaptic signaling pathway through p120ctn, Fer, SHP-2, and β-catenin promotes excitatory synapse development and function.

The Lateral Giant Fiber to Motor Giant Fiber Synapse in Crayfish

1972 ◽  
Vol 30 ◽  
pp. 170-171
Author(s):  
Charles A. Stirling
Keyword(s):  
Synaptic Vesicles ◽  
Procambarus Clarkii ◽  
Synaptic Contact ◽  
Giant Fiber ◽  
Synaptic Junctions

The lateral giant (LG) to motor giant (MoG) synapses in crayfish (Procambarus clarkii) abdominal ganglia are the classic electrotonic synapses. They have previously been described as having synaptic vesicles and as having them on both the pre- and postsynaptic sides of symmetrical synaptic junctions. This positioning of vesicles would make these very atypical synapses, but in the present work on the crayfish Astacus pallipes the motor giant has never been found to contain any type of vesicle at its synapses with the lateral giant fiber.The lateral to motor giant fiber synapses all occur on short branches off the main giant fibers. Closely associated with these giant fiber synapses are two small presynaptic nerves which make synaptic contact with both of the giant fibers and with their small branches.

Substance P: localization in synaptic vesicles in rat central nervous system

1977 ◽  
Vol 29 (4) ◽  
pp. 747-751 ◽  
Author(s):  
A. C. CUELLO ◽  
T. M. JESSELL ◽  
I. KANAZAWA ◽  
L. L. IVERSEN
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Substance P ◽  
Synaptic Vesicles

The effect of 4-(1-naphthylvinyl)-pyridine on the acetylcholine system and on the number of synaptic vesicles in the central nervous system of the rat

1982 ◽  
Vol 4 (2-3) ◽  
pp. 185-193 ◽  
Author(s):  
P KASA ◽  
G SZEPESY ◽  
K GULYA ◽  
K BANSAGHY ◽  
Z RAKONCZAY
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Synaptic Vesicles ◽  
The Central Nervous System
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