A phosphorylation-deubiquitination cascade regulates the BRCA2-RAD51 axis in homologous recombination

• Published in: Genes & development 2016-12, Vol.30 (23), p.2581-2595
• Main Authors: Luo, Kuntian, Li, Lei, Li, Yunhui, Wu, Chenming, Yin, Yujiao, Chen, Yuping, Deng, Min, Nowsheen, Somaira, Yuan, Jian, Lou, Zhenkun
• Format: Article
• Language: English
• Subjects: BRCA2 Protein - genetics; BRCA2 Protein - metabolism; Breast Neoplasms - enzymology; Breast Neoplasms - genetics; Breast Neoplasms - physiopathology; Cell Line, Tumor; Cysteine Endopeptidases - genetics; Cysteine Endopeptidases - metabolism; DNA Repair - genetics; Gene Expression Regulation, Neoplastic - drug effects; Gene Knockout Techniques; HEK293 Cells; Homologous Recombination - drug effects; Homologous Recombination - genetics; Humans; MCF-7 Cells; Phosphorylation - genetics; Poly(ADP-ribose) Polymerase Inhibitors - pharmacology; Protein Binding - genetics; Rad51 Recombinase - genetics; Rad51 Recombinase - metabolism; Radiation Tolerance - drug effects; Radiation Tolerance - genetics; Research Paper; Signal Transduction - genetics; Survival Analysis; Ubiquitination - drug effects; Ubiquitination - genetics
• ISSN: 0890-9369; 1549-5477
• DOI: 10.1101/gad.289439.116

Homologous recombination (HR) is one of the major DNA double-strand break (DSB) repair pathways in mammalian cells. Defects in HR trigger genomic instability and result in cancer predisposition. The defining step of HR is homologous strand exchange directed by the protein RAD51, which is recruited to DSBs by BRCA2. However, the regulation of the BRCA2-RAD51 axis remains unclear. Here we report that ubiquitination of RAD51 hinders RAD51-BRCA2 interaction, while deubiquitination of RAD51 facilitates RAD51-BRCA2 binding and RAD51 recruitment and thus is critical for proper HR. Mechanistically, in response to DNA damage, the deubiquitinase UCHL3 is phosphorylated and activated by ATM. UCHL3, in turn, deubiquitinates RAD51 and promotes the binding between RAD51 and BRCA2. Overexpression of UCHL3 renders breast cancer cells resistant to radiation and chemotherapy, while depletion of UCHL3 sensitizes cells to these treatments, suggesting a determinant role of UCHL3 in cancer therapy. Overall, we identify UCHL3 as a novel regulator of DNA repair and reveal a model in which a phosphorylation-deubiquitination cascade dynamically regulates the BRCA2-RAD51 pathway.