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RNF8 has both KU-dependent and independent roles in chromosomal break repair

Linda Jillianne Tsai1,2, Felicia Wednesday Lopezcolorado1, Ragini Bhargava1,2

  • 1Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA.

Nucleic Acids Research
|May 20, 2020
PubMed

Insights

The E3 ubiquitin ligase RNF8 influences DNA repair. RNF8 suppresses canonical non-homologous end joining (C-NHEJ) but promotes alternative end joining (ALT-EJ) and homology-directed repair (HDR).

Area of Science:

  • Molecular Biology
  • Genetics
  • DNA Repair Mechanisms

Background:

  • Chromosomal double-strand breaks (DSBs) trigger signaling pathways, including ubiquitination, but their impact on repair outcomes is unclear.
  • The E3 ubiquitin ligase RNF8 is involved in DNA damage response, but its specific roles in different DSB repair pathways are not fully elucidated.

Purpose of the Study:

  • To investigate the role of RNF8 in modulating different DNA double-strand break repair pathways.
  • To determine how RNF8 signaling influences end joining and homology-directed repair outcomes.

Main Methods:

  • Utilized an RNA interference screen to identify RNF8's function in DSB repair.
  • Analyzed repair outcomes including deletion rearrangements, end joining (EJ) with and without microhomology, and homology-directed repair (HDR).

Main Results:

  • RNF8 suppresses deletion rearrangements typical of canonical non-homologous end joining (C-NHEJ).
  • RNF8 promotes alternative end joining (ALT-EJ) via microhomology and is crucial for KU-dependent repair events requiring limited end resection.
  • RNF8 also facilitates KU-independent homology-directed repair (HDR), potentially through PALB2, and its role in EJ is distinct from 53BP1 and POLQ.

Conclusions:

  • RNF8 plays a specific role in facilitating DNA repair pathways that involve limited end resection, such as ALT-EJ and HDR.
  • RNF8's functions in ALT-EJ and HDR are mechanistically distinct, with ALT-EJ being KU-dependent and HDR being KU-independent.

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