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DOT1L-mediated RAP80 methylation promotes BRCA1 recruitment to elicit DNA repair

Huangqi Tang1,2, Ya-Fei Lu1, Rongsheng Zeng1

  • 1Shenzhen University International Cancer Center, Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, Marshall Laboratory of Biomedical Engineering, Department of Biochemistry and Molecular Biology, Shenzhen University Medical School, Shenzhen 518055, China.

Proceedings of the National Academy of Sciences of the United States of America
|August 22, 2024
PubMed

Insights

DOT1L methylates RAP80, enabling BRCA1-A complex recruitment to DNA damage sites. This process is crucial for cancer cell radiotherapy resistance and offers a therapeutic target to improve radiosensitivity.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Genetics

Background:

  • Breast Cancer Type 1 Susceptibility Protein (BRCA1) is vital for genome stability and DNA damage repair (DDR).
  • The BRCA1-A complex is recruited to double-strand breaks (DSBs) by RAP80, but RAP80's own recruitment mechanism is unknown.
  • Understanding RAP80 recruitment is key to comprehending DDR and cancer radiotherapy resistance.

Purpose of the Study:

  • To elucidate the mechanism of RAP80 recruitment to DNA damage sites.
  • To investigate the role of DOT1L-mediated RAP80 methylation in BRCA1-A complex chromatin recruitment.
  • To assess the therapeutic potential of targeting DOT1L for overcoming cancer radiotherapy resistance.

Main Methods:

  • Investigated the correlation between DOT1L-mediated RAP80 methylation and BRCA1-A complex recruitment in cancer cells undergoing radiotherapy.
  • Examined the recruitment of DOT1L to chromatin and its methylation of RAP80 following DNA damage.
  • Assessed the binding of methylated RAP80 to ubiquitinated H2A and subsequent BRCA1-A complex recruitment.
  • Evaluated the impact of DOT1L inhibition and RAP80 methylation blockade on cancer cell radiosensitivity in vitro and in vivo.

Main Results:

  • Demonstrated a direct link between DOT1L-mediated RAP80 methylation and BRCA1-A complex recruitment to DSBs during radiotherapy.
  • Showed that DOT1L is rapidly recruited to chromatin and methylates RAP80 at multiple lysine residues upon DNA damage.
  • Confirmed that methylated RAP80 is essential for binding to ubiquitinated H2A, facilitating BRCA1-A complex assembly at DSBs.
  • Found that inhibiting DOT1L or RAP80 methylation significantly enhances cancer cell radiosensitivity.

Conclusions:

  • Revealed a critical role for DOT1L in DDR by initiating the recruitment of RAP80 and the BRCA1-A complex to chromatin.
  • Established DOT1L-catalyzed RAP80 methylation as a key step in the DNA damage response pathway.
  • Highlighted the therapeutic relevance of targeting DOT1L to enhance tumor radiosensitivity and overcome radiotherapy resistance.
Keywords:
BRCA1DNA damage repairDOT1LRAP80histone modification

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