2. Academic Validation
  3. RAP80 phase separation at DNA double-strand break promotes BRCA1 recruitment

RAP80 phase separation at DNA double-strand break promotes BRCA1 recruitment

  • Nucleic Acids Res. 2023 Aug 28;gkad686. doi: 10.1093/nar/gkad686.
Caolitao Qin 1 2 3,  Yun-Long Wang 1 4 5 2,  Jin-Ying Zhou 1 4 5,  Jie Shi 2 3,  Wan-Wen Zhao 2 3,  Ya-Xi Zhu 3 6,  Shao-Mei Bai 3 6,  Li-Li Feng 5 2 7,  Shu-Ying Bie 1 3 6,  Bing Zeng 3 8,  Jian Zheng 2 3,  Guang-Dong Zeng 2 3,  Wei-Xing Feng 2 3,  Xiang-Bo Wan 1 4 5 2,  Xin-Juan Fan 1 4 3 6
Affiliations

Affiliations

  • 1 Henan Provincial Key Laboratory of Radiation Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
  • 2 Department of Radiation Oncology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510655, P.R. China.
  • 3 GuangDong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510655, P.R. China.
  • 4 Academy of Medical Sciences, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
  • 5 Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
  • 6 Department of Pathology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510655, P.R. China.
  • 7 State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510655, P.R. China.
  • 8 Department of Gastroenterology, Hernia and Abdominal Wall Surgery, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510655, P.R. China.
PMID: 37638744 DOI: 10.1093/nar/gkad686
Abstract

RAP80 has been characterized as a component of the BRCA1-A complex and is responsible for the recruitment of BRCA1 to DNA double-strand breaks (DSBs). However, we and Others found that the recruitment of RAP80 and BRCA1 were not absolutely temporally synchronized, indicating that other mechanisms, apart from physical interaction, might be implicated. Recently, liquid-liquid phase separation (LLPS) has been characterized as a novel mechanism for the organization of key signaling molecules to drive their particular cellular functions. Here, we characterized that RAP80 LLPS at DSB was required for RAP80-mediated BRCA1 recruitment. Both cellular and in vitro experiments showed that RAP80 phase separated at DSB, which was ascribed to a highly disordered region (IDR) at its N-terminal. Meanwhile, the Lys63-linked poly-ubiquitin chains that quickly formed after DSBs occur, strongly enhanced RAP80 phase separation and were responsible for the induction of RAP80 condensation at the DSB site. Most importantly, abolishing the condensation of RAP80 significantly suppressed the formation of BRCA1 foci, encovering a pivotal role of RAP80 condensates in BRCA1 recruitment and radiosensitivity. Together, our study disclosed a new mechanism underlying RAP80-mediated BRCA1 recruitment, which provided new insight into the role of phase separation in DSB repair.

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