Efa6 protects axons and regulates their growth and branching by inhibiting microtubule polymerisation at the cortex

  1. Yue Qu
  2. Ines Hahn  Is a corresponding author
  3. Meredith Lees
  4. Jill Parkin
  5. André Voelzmann
  6. Karel Dorey
  7. Alex Rathbone
  8. Claire T Friel
  9. Victoria J Allan
  10. Pilar Okenve-Ramos
  11. Natalia Sanchez-Soriano
  12. Andreas Prokop
  1. University of Manchester, United Kingdom
  2. University of Nottingham, United Kingdom
  3. University of Liverpool, United Kingdom

Abstract

Cortical collapse factors affect microtubule (MT) dynamics at the plasma membrane. They play important roles in neurons, as suggested by inhibition of axon growth and regeneration through the Arf activator Efa6 in C. elegans, and by neurodevelopmental disorders linked to the mammalian kinesin Kif21A. How cortical collapse factors influence axon growth is little understood. Here we studied them, focussing on the function of Drosophila Efa6 in experimentally and genetically amenable fly neurons. First, we show that Drosophila Efa6 can inhibit MTs directly without interacting molecules via an N-terminal 18 amino acid motif (MT elimination domain/MTED) that binds tubulin and inhibits microtubule growth in vitro and cells. If N-terminal MTED-containing fragments are in the cytoplasm they abolish entire microtubule networks of mouse fibroblasts and whole axons of fly neurons. Full-length Efa6 is membrane-attached, hence primarily blocks MTs in the periphery of fibroblasts, and explorative MTs that have left axonal bundles in neurons. Accordingly, loss of Efa6 causes an increase of explorative MTs: in growth cones they enhance axon growth, in axon shafts they cause excessive branching, as well as atrophy through perturbations of MT bundles. Efa6 over-expression causes the opposite phenotypes. Taken together, our work conceptually links molecular and sub-cellular functions of cortical collapse factors to axon growth regulation and reveals new roles in axon branching and in the prevention of axonal atrophy. Furthermore, the MTED delivers a promising tool that can be used to inhibit MTs in a compartmentalised fashion when fusing it to specifically localising protein domains.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided.

Article and author information

Author details

  1. Yue Qu

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  2. Ines Hahn

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    For correspondence
    ines.hahn@manchester.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7703-8160
  3. Meredith Lees

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Jill Parkin

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  5. André Voelzmann

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7682-5637
  6. Karel Dorey

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  7. Alex Rathbone

    School of Life Sciences, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  8. Claire T Friel

    School of Life Sciences, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  9. Victoria J Allan

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  10. Pilar Okenve-Ramos

    Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7513-6557
  11. Natalia Sanchez-Soriano

    Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  12. Andreas Prokop

    Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-8482-3298

Funding

Biotechnology and Biological Sciences Research Council (BB/I002448/1)

  • Andreas Prokop

Biotechnology and Biological Sciences Research Council (BB/P020151/1)

  • Andreas Prokop

Biotechnology and Biological Sciences Research Council (BB/L000717/1)

  • Andreas Prokop

Biotechnology and Biological Sciences Research Council (BB/M007553/1)

  • Andreas Prokop

Biotechnology and Biological Sciences Research Council (BB/M007456/1)

  • Natalia Sanchez-Soriano

Biotechnology and Biological Sciences Research Council (BB/J005983/1)

  • Karel Dorey

Leverhulme Trust (ECF-2017-247)

  • Ines Hahn

Deutsche Forschungsgemeinschaft (VO 2071/1-1)

  • André Voelzmann

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Mohan K Balasubramanian, University of Warwick, United Kingdom

Ethics

Animal experimentation: All experiments involving Xenopus laevis were approved by the Ethical Review Committe of the University of Manchester and a Home Office license (ref . PFDA14F2D).

Version history

  1. Received: July 18, 2019
  2. Accepted: November 6, 2019
  3. Accepted Manuscript published: November 13, 2019 (version 1)
  4. Version of Record published: November 27, 2019 (version 2)

Copyright

© 2019, Qu 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.

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  1. Yue Qu
  2. Ines Hahn
  3. Meredith Lees
  4. Jill Parkin
  5. André Voelzmann
  6. Karel Dorey
  7. Alex Rathbone
  8. Claire T Friel
  9. Victoria J Allan
  10. Pilar Okenve-Ramos
  11. Natalia Sanchez-Soriano
  12. Andreas Prokop
(2019)
Efa6 protects axons and regulates their growth and branching by inhibiting microtubule polymerisation at the cortex
eLife 8:e50319.
https://doi.org/10.7554/eLife.50319

Share this article

https://doi.org/10.7554/eLife.50319

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