BRCA1 Directs the Repair Pathway to Homologous Recombination by Promoting 53BP1 Dephosphorylation
Mayu Isono,
Atsuko Niimi,
Takahiro Oike,
Yoshihiko Hagiwara,
Hiro Sato,
Ryota Sekine,
Yukari Yoshida,
Shin-Ya Isobe,
Chikashi Obuse,
Ryotaro Nishi,
Elena Petricci,
Shinichiro Nakada,
Takashi Nakano,
Atsushi Shibata
Affiliations
Mayu Isono
Advanced Scientific Research Leaders Development Unit, Gunma University, Maebashi, Gunma 371-8511, Japan; Gunma University Heavy Ion Medical Center, Gunma University, Maebashi, Gunma 371-8511, Japan
Atsuko Niimi
Gunma University Initiative for Advanced Research, Gunma University, Maebashi, Gunma 371-8511, Japan
Takahiro Oike
Department of Radiation Oncology, Gunma University, Maebashi, Gunma 371-8511, Japan
Yoshihiko Hagiwara
Advanced Scientific Research Leaders Development Unit, Gunma University, Maebashi, Gunma 371-8511, Japan; Department of Radiation Oncology, Gunma University, Maebashi, Gunma 371-8511, Japan
Hiro Sato
Department of Radiation Oncology, Gunma University, Maebashi, Gunma 371-8511, Japan
Ryota Sekine
Advanced Scientific Research Leaders Development Unit, Gunma University, Maebashi, Gunma 371-8511, Japan
Yukari Yoshida
Gunma University Heavy Ion Medical Center, Gunma University, Maebashi, Gunma 371-8511, Japan
Shin-Ya Isobe
Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
Chikashi Obuse
Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
Ryotaro Nishi
Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
Elena Petricci
Department of Biotechnology, Chemistry, and Pharmacy, Università degli Studi di Siena, 53100 Siena, Italy
Shinichiro Nakada
Department of Bioregulation and Cellular Response, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
Takashi Nakano
Gunma University Heavy Ion Medical Center, Gunma University, Maebashi, Gunma 371-8511, Japan; Gunma University Initiative for Advanced Research, Gunma University, Maebashi, Gunma 371-8511, Japan; Department of Radiation Oncology, Gunma University, Maebashi, Gunma 371-8511, Japan
Atsushi Shibata
Advanced Scientific Research Leaders Development Unit, Gunma University, Maebashi, Gunma 371-8511, Japan; Corresponding author
Summary: BRCA1 promotes homologous recombination (HR) by activating DNA-end resection. By contrast, 53BP1 forms a barrier that inhibits DNA-end resection. Here, we show that BRCA1 promotes DNA-end resection by relieving the 53BP1-dependent barrier. We show that 53BP1 is phosphorylated by ATM in S/G2 phase, promoting RIF1 recruitment, which inhibits resection. 53BP1 is promptly dephosphorylated and RIF1 released, despite remaining unrepaired DNA double-strand breaks (DSBs). When resection is impaired by CtIP/MRE11 endonuclease inhibition, 53BP1 phosphorylation and RIF1 are sustained due to ongoing ATM signaling. BRCA1 depletion also sustains 53BP1 phosphorylation and RIF1 recruitment. We identify the phosphatase PP4C as having a major role in 53BP1 dephosphorylation and RIF1 release. BRCA1 or PP4C depletion impairs 53BP1 repositioning, EXO1 recruitment, and HR progression. 53BP1 or RIF1 depletion restores resection, RAD51 loading, and HR in PP4C-depleted cells. Our findings suggest that BRCA1 promotes PP4C-dependent 53BP1 dephosphorylation and RIF1 release, directing repair toward HR. : Following induction of DNA double-strand break, a pro-end-joining environment is created in G2 by transient 53BP1 phosphorylation and RIF1 recruitment. Here, Isono et al. show that, if timely repair does not ensue, BRCA1 promotes 53BP1 dephosphorylation and RIF1 release, favoring repair by homologous recombination. Keywords: ATM, DNA-end resection, BRCA1, 53BP1, RIF1, PP4C, NHEJ, HR
