DNA damage induces nuclear actin filament assembly by formin-2 and Spire-1/2 that promotes efficient DNA repair

  1. Brittany J Belin
  2. Terri Lee
  3. R Dyche Mullins  Is a corresponding author
  1. University of California, San Francisco, United States

Abstract

Actin filaments assemble inside the nucleus in response to multiple cellular perturbations, including heat shock, protein misfolding, integrin engagement, and serum stimulation. We find that DNA damage also generates nuclear actin filaments−detectable by phalloidin and live-cell actin probes−with three characteristic morphologies: (i) long, nucleoplasmic filaments; (ii) short, nucleolus-associated filaments; and (iii) dense, nucleoplasmic clusters. This DNA damage-induced nuclear actin assembly requires two biologically and physically linked nucleation factors: formin-2 and Spire-1/Spire-2. Formin-2 accumulates in the nucleus after DNA damage, and depletion of either formin-2 or actin's nuclear import factor, importin-9, increases the number of DNA double-strand breaks (DSBs), linking nuclear actin filaments to efficient DSB clearance. Nuclear actin filaments are also required for nuclear oxidation induced by acute genotoxic stress. Our results reveal a previously unknown role for nuclear actin filaments in DNA repair and identify the molecular mechanisms creating these nuclear filaments.

Article and author information

Author details

  1. Brittany J Belin

    Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Terri Lee

    Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. R Dyche Mullins

    Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
    For correspondence
    Dyche.Mullins@ucsf.edu
    Competing interests
    The authors declare that no competing interests exist.

Copyright

© 2015, Belin 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

  • 7,953
    views
  • 2,066
    downloads
  • 169
    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. Brittany J Belin
  2. Terri Lee
  3. R Dyche Mullins
(2015)
DNA damage induces nuclear actin filament assembly by formin-2 and Spire-1/2 that promotes efficient DNA repair
eLife 4:e07735.
https://doi.org/10.7554/eLife.07735

Share this article

https://doi.org/10.7554/eLife.07735

Further reading

    1. Cell Biology
    Johanna Odenwald, Bernardo Gabiatti ... Susanne Kramer
    Research Article

    Immunofluorescence localises proteins via fluorophore-labelled antibodies. However, some proteins evade detection due to antibody-accessibility issues or because they are naturally low abundant or antigen density is reduced by the imaging method. Here, we show that the fusion of the target protein to the biotin ligase TurboID and subsequent detection of biotinylation by fluorescent streptavidin offers an ‘all in one’ solution to these restrictions. For all proteins tested, the streptavidin signal was significantly stronger than an antibody signal, markedly improving the sensitivity of expansion microscopy and correlative light and electron microscopy. Importantly, proteins within phase-separated regions, such as the central channel of the nuclear pores, the nucleolus, or RNA granules, were readily detected with streptavidin, while most antibodies failed. When TurboID is used in tandem with an HA epitope tag, co-probing with streptavidin and anti-HA can map antibody-accessibility and we created such a map for the trypanosome nuclear pore. Lastly, we show that streptavidin imaging resolves dynamic, temporally, and spatially distinct sub-complexes and, in specific cases, reveals a history of dynamic protein interaction. In conclusion, streptavidin imaging has major advantages for the detection of lowly abundant or inaccessible proteins and in addition, provides information on protein interactions and biophysical environment.