1. Cancer Biology
  2. Stem Cells and Regenerative Medicine
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RAL GTPases mediate EGFR-driven intestinal stem cell proliferation and tumourigenesis

  1. Máté Nászai
  2. Karen Bellec
  3. Yachuan Yu
  4. Alvaro Román-Fernández
  5. Emma Sandilands
  6. Joel Johansson
  7. Andrew D Campbell
  8. Jim C Norman
  9. Owen J Sansom
  10. David M Bryant
  11. Julia B Cordero  Is a corresponding author
  1. University of Oxford, United Kingdom
  2. University of Glasgow, United Kingdom
  3. CRUK Beatson Institute, United Kingdom
  4. Beatson Institute, United Kingdom
Research Article
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Cite this article as: eLife 2021;10:e63807 doi: 10.7554/eLife.63807

Abstract

RAS-like (RAL) GTPases function in Wnt signalling-dependent intestinal stem cell proliferation and regeneration. Whether RAL proteins work as canonical RAS effectors in the intestine, and the mechanisms of how they contribute to tumourigenesis remain unclear. Here, we show that RAL GTPases are necessary and sufficient to activate EGFR/MAPK signalling in the intestine, via induction of EGFR internalisation. Knocking down Drosophila RalA from intestinal stem and progenitor cells leads to increased levels of plasma membrane-associated EGFR and decreased MAPK pathway activation. Importantly, in addition to impacting stem cell proliferation during damage-induced intestinal regeneration, this role of RAL GTPases impacts on EGFR-dependent tumorigenic growth in the intestine and in human mammary epithelium. However, the effect of oncogenic RAS in the intestine is independent from RAL function. Altogether, our results reveal previously unrecognised cellular and molecular contexts where RAL GTPases become essential mediators of adult tissue homeostasis and malignant transformation.

Data availability

All data underlying the findings of this study are included in the manuscript and supporting file. Source data files have been provided for all figures containing numeric data. The entire raw data set corresponding to the work in this paper will be publicly available at the time of publication from our institutional repository http://dx.doi.org/10.5525/gla.researchdata.1142. RNA sequencing data has been deposited in GEO (accession GSE162421) and can be accessed through (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE162421). Custom scripts used for quantification are available at Github: https://github.com/emltwc/TracheaProject/blob/master/Blind_scoring.ijm; https://github.com/emltwc/2018-Cell-Stem-Cell and https://github.com/emltwc/EGFRProject .

The following data sets were generated

Article and author information

Author details

  1. Máté Nászai

    University of Oxford, Oxford, United Kingdom
    Competing interests
    No competing interests declared.
  2. Karen Bellec

    University of Glasgow, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  3. Yachuan Yu

    N/A, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  4. Alvaro Román-Fernández

    N/A, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  5. Emma Sandilands

    Institute of Cancer Sciences, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  6. Joel Johansson

    CRUK Beatson Institute, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  7. Andrew D Campbell

    CRUK Beatson Institute, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  8. Jim C Norman

    Integrin Cell Biologu, Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
  9. Owen J Sansom

    Institute of Cancer Sciences, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    Owen J Sansom, O.J.S. has received funding from Novartis to examine RAL and RAL GEFs in malignancy..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9540-3010
  10. David M Bryant

    Institute of Cancer Sciences, CRUK Beatson Institute, Glasgow, United Kingdom
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2721-5012
  11. Julia B Cordero

    University of Glasgow, Glasgow, United Kingdom
    For correspondence
    julia.cordero@glasgow.ac.uk
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1701-9480

Funding

Wellcome Trust (104103/Z/14/Z)

  • Julia B Cordero

Cancer Research UK (A17196)

  • Yachuan Yu

Cancer Research UK (A18277,C596/A18076)

  • Jim C Norman

Cancer Research UK (A21139)

  • Joel Johansson
  • Andrew D Campbell
  • Owen J Sansom

Cancer Research UK (A17196)

  • Alvaro Román-Fernández
  • Emma Sandilands
  • David M Bryant

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

Ethics

Animal experimentation: All animal work has been approved by a University of Glasgow internal ethics committee and performed in accordance with institutional guidelines under personal and project licenses granted by the UK Home Office (PPL PCD3046BA).

Reviewing Editor

  1. Hugo J Bellen, Baylor College of Medicine, United States

Publication history

  1. Received: October 7, 2020
  2. Accepted: June 3, 2021
  3. Accepted Manuscript published: June 7, 2021 (version 1)
  4. Version of Record published: June 21, 2021 (version 2)

Copyright

© 2021, Nászai 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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