Topic
Synaptic vesicle budding
About: Synaptic vesicle budding is a research topic. Over the lifetime, 4 publications have been published within this topic receiving 643 citations.
Papers
TL;DR: The generation of SVs from PC12 cell membranes requires ARF and uses its GTPase activity, probably to regulate coating phenomena, according to in vitro incubation in the presence of mutant ARFs, suggesting that the two ARF mutations block at different biosynthetic steps.
Abstract: Carrier vesicle generation from donor membranes typically progresses through a GTP-dependent recruitment of coats to membranes. Here we explore the role of ADP ribosylation factor (ARF) 1, one of the GTP-binding proteins that recruit coats, in the production of neuroendocrine synaptic vesicles (SVs) from PC12 cell membranes. Brefeldin A (BFA) strongly and reversibly inhibited SV formation in vivo in three different PC12 cell lines expressing vesicle-associated membrane protein-T Antigen derivatives. Other membrane traffic events remained unaffected by the drug, and the BFA effects were not mimicked by drugs known to interfere with formation of other classes of vesicles. The involvement of ARF proteins in the budding of SVs was addressed in a cell-free reconstitution system (Desnos, C., L. Clift-O'Grady, and R.B. Kelly. 1995. J. Cell Biol. 130:1041-1049). A peptide spanning the effector domain of human ARF1 (2-17) and recombinant ARF1 mutated in its GTPase activity, both inhibited the formation of SVs of the correct size. During in vitro incubation in the presence of the mutant ARFs, the labeled precursor membranes acquired different densities, suggesting that the two ARF mutations block at different biosynthetic steps. Cell-free SV formation in the presence of a high molecular weight, ARF-depleted fraction from brain cytosol was significantly enhanced by the addition of recombinant myristoylated native ARF1. Thus, the generation of SVs from PC12 cell membranes requires ARF and uses its GTPase activity, probably to regulate coating phenomena.
100 citations
TL;DR: In vivo results demonstrate the involvement of an EHD1/3 ortholog in clathrin/dynamin-dependent synaptic vesicle budding and suggest that l-EHD acts to limit the formation of long, unproductive dynamin helices, thereby promoting vesicles budding.
Abstract: Eps15 homology domain-containing proteins (EHDs) are conserved ATPases implicated in membrane remodeling Recently, EHD1 was found to be enriched at synaptic release sites, suggesting a possible involvement in the trafficking of synaptic vesicles We have investigated the role of an EHD1/3 ortholog (l-EHD) in the lamprey giant reticulospinal synapse l-EHD was detected by immunogold at endocytic structures adjacent to release sites In antibody microinjection experiments, perturbation of l-EHD inhibited synaptic vesicle endocytosis and caused accumulation of clathrin-coated pits with atypical, elongated necks The necks were covered with helix-like material containing dynamin To test whether l-EHD directly interferes with dynamin function, we used fluid-supported bilayers as in vitro assay We found that l-EHD strongly inhibited vesicle budding induced by dynamin in the constant presence of GTP l-EHD also inhibited dynamin-induced membrane tubulation in the presence of GTPγS, a phenomenon linked with dynamin helix assembly Our in vivo results demonstrate the involvement of l-EHD in clathrin/dynamin-dependent synaptic vesicle budding Based on our in vitro observations, we suggest that l-EHD acts to limit the formation of long, unproductive dynamin helices, thereby promoting vesicle budding
52 citations
TL;DR: Observations indicate that endophilin A is essential for synaptic vesicle endocytosis, being required from the onset of budding until fission.
Abstract: We characterized Drosophila endophilin A (D-endoA), and generated and analysed D-endoA mutants. Like its mammalian homologue, D-endoA exhibits lysophosphatidic acid acyl transferase activity and contains a functional SH3 domain. D-endoA is recruited to the sites of endocytosis, as revealed by immunocytochemistry of the neuromuscular junction (NMJ) of mutant L3 larvae carrying the temperature-sensitive allele of dynamin, shibire. D-endoA null mutants show severe defects in motility and die at the early L2 larval stage. Mutants with reduced D-endoA levels exhibit a range of defects of synaptic vesicle endocytosis, as observed at L3 larvae NMJs using FM1-43 uptake and electron microscopy. NMJs with an almost complete loss of synaptic vesicles did not show an accumulation of intermediates of the budding process, whereas NMJs with only slightly reduced levels of synaptic vesicles showed a striking increase in early-stage, but not late-stage, budding intermediates at the plasma membrane. Together with results of previous studies, these observations indicate that endophilin A is essential for synaptic vesicle endocytosis, being required from the onset of budding until fission.
TL;DR: It is suggested that endosome-like intermediates of nerve terminals originate by bulk uptake of the plasma membrane and that clathrin- and dynamin-mediated budding takes place in parallel from the plasmalemma and from these internal membranes.
Abstract: Strong evidence implicates clathrin-coated vesicles and endosome-like vacuoles in the reformation of synaptic vesicles after exocytosis, and it is generally assumed that these vacuoles represent a traffic station downstream from clathrin-coated vesicles. To gain insight into the mechanisms of synaptic vesicle budding from endosome-like intermediates, lysed nerve terminals and nerve terminal membrane subfractions were examined by EM after incubations with GTP gamma S. Numerous clathrin-coated budding intermediates that were positive for AP2 and AP180 immunoreactivity and often collared by a dynamin ring were seen. These were present not only on the plasma membrane (Takei, K., P.S. McPherson, S.L.Schmid, and P. De Camilli. 1995. Nature (Lond.). 374:186-190), but also on internal vacuoles. The lumen of these vacuoles retained extracellular tracers and was therefore functionally segregated from the extracellular medium, although narrow connections between their membranes and the plasmalemma were sometimes visible by serial sectioning. Similar observations were made in intact cultured hippocampal neurons exposed to high K+ stimulation. Coated vesicle buds were generally in the same size range of synaptic vesicles and positive for the synaptic vesicle protein synaptotagmin. Based on these results, we suggest that endosome-like intermediates of nerve terminals originate by bulk uptake of the plasma membrane and that clathrin- and dynamin-mediated budding takes place in parallel from the plasmalemma and from these internal membranes. We propose a synaptic vesicle recycling model that involves a single vesicle budding step mediated by clathrin and dynamin.
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| Year | Papers |
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| 2011 | 1 |
| 2002 | 1 |
| 1997 | 1 |
| 1996 | 1 |