v-SNARE Composition Distinguishes Synaptic Vesicle Pools

Department of Neurology, University of California, San Francisco School of Medicine, San Francisco, CA 94143, USA.
Neuron (Impact Factor: 15.98). 08/2011; 71(3):474-87. DOI: 10.1016/j.neuron.2011.06.010
Source: PubMed

ABSTRACT Synaptic vesicles belong to two distinct pools, a recycling pool responsible for the evoked release of neurotransmitter and a resting pool unresponsive to stimulation. The uniform appearance of synaptic vesicles has suggested that differences in location or cytoskeletal association account for these differences in function. We now find that the v-SNARE tetanus toxin-insensitive vesicle-associated membrane protein (VAMP7) differs from other synaptic vesicle proteins in its distribution to the two pools, providing evidence that they differ in molecular composition. We also find that both resting and recycling pools undergo spontaneous release, and when activated by deletion of the longin domain, VAMP7 influences the properties of release. Further, the endocytosis that follows evoked and spontaneous release differs in mechanism, and specific sequences confer targeting to the different vesicle pools. The results suggest that different endocytic mechanisms generate synaptic vesicles with different proteins that can endow the vesicles with distinct properties.

Download full-text


Available from: Sergio Leal-Ortiz, Aug 17, 2015
1 Follower
  • Source
    • "This task is inherently more complex as SVs are homogenous in size and display a defined protein and lipid composition that can only be maintained by high fidelity adaptor-mediated sorting processes that serve to ''proofread'' SV composition. This task may be further complicated by the existence of functionally distinct pools of vesicles that may display compositional heterogeneity (Hua et al., 2011b; Raingo et al., 2012; Ramirez et al., 2012). However, CME as well as endosomal pathways of vesicle budding employed to reform functional SVs operate on a timescale of tens of seconds and, thus, provide a potential kinetic bottleneck when used for compensatory membrane retrieval at synapses undergoing high rates of firing. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The function of the nervous system depends on the exocytotic release of neurotransmitter from synaptic vesicles (SVs). To sustain neurotransmission, SV membranes need to be retrieved, and SVs have to be reformed locally within presynaptic nerve terminals. In spite of more than 40 years of research, the mechanisms underlying presynaptic membrane retrieval and SV recycling remain controversial. Here, we review the current state of knowledge in the field, focusing on the molecular mechanism involved in presynaptic membrane retrieval and SV reformation. We discuss the challenges associated with studying these pathways and present perspectives for future research.
    Neuron 02/2015; 85(3):484-496. DOI:10.1016/j.neuron.2014.12.016 · 15.98 Impact Factor
  • Source
    • "Kinetin Blocks Mitochondrial Motility in Axons in a PINK1-Dependent Manner Increasing PINK1 activity markedly decreases the mobility of axonal mitochondria, and this is thought to be the first step in the sequestration and removal of damaged mitochondria (Wang et al., 2011). To determine whether PINK1 activation by kinetin also decreases mitochondrial motility, we examined the mobility of axonal mitochondria in rat hippocampal neurons cotransfected with mitoGFP to identify mitochondria and N-terminal mCherry-tagged synaptophysin to identify axons (Hua et al., 2011; Nakamura et al., 2011). Cells were pretreated for 48 hr with 50 mM kinetin, adenine, 9-methyl-kinetin (9MK, shown in Figure 4A), or equivalent DMSO, and mitochondrial motility was imaged live. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mitochondria have long been implicated in the pathogenesis of Parkinson's disease (PD). Mutations in the mitochondrial kinase PINK1 that reduce kinase activity are associated with mitochondrial defects and result in an autosomal-recessive form of early-onset PD. Therapeutic approaches for enhancing the activity of PINK1 have not been considered because no allosteric regulatory sites for PINK1 are known. Here, we show that an alternative strategy, a neo-substrate approach involving the ATP analog kinetin triphosphate (KTP), can be used to increase the activity of both PD-related mutant PINK1(G309D) and PINK1(WT). Moreover, we show that application of the KTP precursor kinetin to cells results in biologically significant increases in PINK1 activity, manifest as higher levels of Parkin recruitment to depolarized mitochondria, reduced mitochondrial motility in axons, and lower levels of apoptosis. Discovery of neo-substrates for kinases could provide a heretofore-unappreciated modality for regulating kinase activity.
    Cell 08/2013; 154(4):737-47. DOI:10.1016/j.cell.2013.07.030 · 33.12 Impact Factor
  • Source
    • "They also showed evidence that spontaneously released vesicles are mobilized from a resting pool, which was originally described as an activity-independent set of vesicles that do not participate in vesicle cycling. More recently, two elegant studies provided additional evidence that vesicles from the resting pool are more prompt to recycle spontaneously and this might involve different proteins other than the canonic SNARES (Hua et al., 2011; Ramirez & Kavalali, 2012). In agreement with this hypothesis, we showed that under MbCD treatment there an enlargement of synaptic vesicles and modest FM1-43 uptake, suggesting that at least for the frog NMJ, synaptic vesicles recycle differently after cholesterol removal. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the effects of cholesterol removal on spontaneous and KCl-evoked synaptic vesicle recycling at the frog neuromuscular junction. Cholesterol removal by methyl-β-cyclodextrin (MβCD) induced an increase in the frequency of miniature end-plate potentials (MEPPs) and spontaneous destaining of synaptic vesicles labeled with the styryl dye FM1-43. Treatment with MβCD also increased the size of MEPPs without causing significant changes in nicotinic receptor clustering. At the ultrastructural level, synaptic vesicles from nerve terminals treated with MβCD were larger than those from control. In addition, treatment with MβCD reduced the fusion of synaptic vesicles that are mobilized during KCl-evoked stimulation, but induced recycling of those vesicles that fuse spontaneously. We therefore suggest that MβCD might favor the release of vesicles that belong to a pool that is different from that involved in the KCl-evoked release. These results reveal fundamental differences in the synaptic vesicle cycle for spontaneous and evoked release, and suggest that deregulation of cholesterol affects synaptic vesicle biogenesis and increases transmitter packing.
    European Journal of Neuroscience 07/2013; 38. DOI:10.1111/ejn.12300 · 3.67 Impact Factor
Show more