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The E3 ligase RNF8 regulates KU80 removal and NHEJ repair

Nature Structural & Molecular Biology volume 19, pages 201206 (2012) | Download Citation

Abstract

The ubiquitination cascade has a key role in the assembly of repair and signaling proteins at sites of double-strand DNA breaks. The E3 ubiquitin ligase RING finger protein 8 (RNF8) triggers the initial ubiquitination at double-strand DNA breaks, whereas sustained ubiquitination requires the downstream E3 ligase RING finger protein 168 (RNF168). It is not known whether RNF8 and RNF168 have discrete substrates and/or form different ubiquitin chains. Here we show that RNF168 acts with the ubiquitin-conjugating enzyme E2 13 (UBC13) and specifically synthesizes Lys63-linked chains, whereas RNF8 primarily forms Lys48-linked chains on chromatin, which promote substrate degradation. We also find that RNF8 regulates the abundance of the nonhomologous end-joining (NHEJ) repair protein KU80 at sites of DNA damage, and that RNF8 depletion results in prolonged retention of KU80 at damage sites and impaired nonhomologous end-joining repair. These findings reveal a distinct feature of RNF8 and indicate the involvement of the ubiquitination-mediated degradation pathway in DNA damage repair.

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Acknowledgements

We thank our colleagues in the Chen laboratory for insightful discussions and technical assistance. We also thank X. Zhang and H.P. Adams for technical assistance with the laser microirradiation. This work was supported in part by grants from the US National Institutes of Health (CA089239 and CA092312 to J.C.). J.C. is a recipient of an Era of Hope Scholar award from the US Department of Defense (W81XWH-05-1-0470) and is a member of the MD Anderson Cancer Center (CA016672).

Author information

Affiliations

  1. Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.

    • Lin Feng
    •  & Junjie Chen

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Contributions

L.F. designed and carried out the experiments. J.C. advised on the design of the experiments. L.F. and J.C. were responsible for the preparation of the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Junjie Chen.

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DOI

https://doi.org/10.1038/nsmb.2211

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