Arf6 regulates the cycling and the readily releasable pool of synaptic vesicles at hippocampal synapse

  1. Erica Tagliatti
  2. Manuela Fadda
  3. Antonio Falace
  4. Fabio Benfenati
  5. Anna Fassio  Is a corresponding author
  1. Fondazione Istituto Italiano di Tecnologia, Italy
  2. University of Genova, Italy
  3. Institut national de la santé et de la recherche médicale, Institut de Neurobiologie de la Méditerranée, France

Abstract

Recycling of synaptic vesicles (SVs) is a fundamental step in the process of neurotransmission. Endocytosed SV can travel directly into the recycling pool or recycle through endosomes but little is known about the molecular actors regulating the switch between these SV recycling routes. ADP ribosylation factor 6 (Arf6) is a small GTPase known to participate in constitutive trafficking between plasma membrane and early endosomes. Here we have morphologically and functionally investigated Arf6-silenced hippocampal synapses and found an activity dependent accumulation of synaptic endosome-like organelles and increased release-competent docked SVs. These features were phenocopied by pharmacological blockage of Arf6 activation. The data reveal an unexpected role for this small GTPase in reducing the size of the readily releasable pool of SVs and in channeling retrieved SVs toward direct recycling rather than endosomal sorting. We propose that Arf6 acts at the presynapse to define the fate of an endocytosed SV.

Article and author information

Author details

  1. Erica Tagliatti

    Center of SynapticNeuroscience, Fondazione Istituto Italiano di Tecnologia, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.
  2. Manuela Fadda

    Department of Experimental Medicine, University of Genova, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.
  3. Antonio Falace

    Institut national de la santé et de la recherche médicale, Institut de Neurobiologie de la Méditerranée, Marseille, France
    Competing interests
    The authors declare that no competing interests exist.
  4. Fabio Benfenati

    Center of SynapticNeuroscience, Fondazione Istituto Italiano di Tecnologia, Genova, Italy
    Competing interests
    The authors declare that no competing interests exist.
  5. Anna Fassio

    Center of SynapticNeuroscience, Fondazione Istituto Italiano di Tecnologia, Genova, Italy
    For correspondence
    afassio@unige.it
    Competing interests
    The authors declare that no competing interests exist.

Ethics

Animal experimentation: All experiments were carried out in accordance with the guidelines established by the European Communities Council (Directive 2010/63/EU of March 4th 2014) and were approved by the Italian Ministry of Health.

Copyright

© 2016, Tagliatti et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 2,683
    views
  • 625
    downloads
  • 48
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Erica Tagliatti
  2. Manuela Fadda
  3. Antonio Falace
  4. Fabio Benfenati
  5. Anna Fassio
(2016)
Arf6 regulates the cycling and the readily releasable pool of synaptic vesicles at hippocampal synapse
eLife 5:e10116.
https://doi.org/10.7554/eLife.10116

Share this article

https://doi.org/10.7554/eLife.10116

Further reading

    1. Neuroscience
    Mazen Makke, Alejandro Pastor-Ruiz ... Dieter Bruns
    Research Article

    Complexin determines magnitude and kinetics of synchronized secretion, but the underlying molecular mechanisms remained unclear. Here, we show that the hydrophobic face of the amphipathic helix at the C-terminus of Complexin II (CpxII, amino acids 115–134) binds to fusion-promoting SNARE proteins, prevents premature secretion, and allows vesicles to accumulate in a release-ready state in mouse chromaffin cells. Specifically, we demonstrate that an unrelated amphipathic helix functionally substitutes for the C-terminal domain (CTD) of CpxII and that amino acid substitutions on the hydrophobic side compromise the arrest of the pre-fusion intermediate. To facilitate synchronous vesicle fusion, the N-terminal domain (NTD) of CpxII (amino acids 1–27) specifically cooperates with synaptotagmin I (SytI), but not with synaptotagmin VII. Expression of CpxII rescues the slow release kinetics of the Ca2+-binding mutant Syt I R233Q, whereas the N-terminally truncated variant of CpxII further delays it. These results indicate that the CpxII NTD regulates mechanisms which are governed by the forward rate of Ca2+ binding to Syt I. Overall, our results shed new light on key molecular properties of CpxII that hinder premature exocytosis and accelerate synchronous exocytosis.

    1. Neuroscience
    Bharath Krishnan, Noah Cowan
    Insight

    Mice can generate a cognitive map of an environment based on self-motion signals when there is a fixed association between their starting point and the location of their goal.