USP52 regulates DNA end resection and chemosensitivity through removing inhibitory ubiquitination from CtIP

Ming Gao,Min Deng,Guijie Guo,Chao Zhang,Wootae Kim,Xinyi Tu,Ping Yin,Zhenkun Lou,Qin Zhou,Jinzhou Huang,Fei Zhao,Jake A Kloeber,Kuntian Luo

doi:10.1038/s41467-020-19202-0

Abstract

Human C-terminal binding protein (CtBP)–interacting protein (CtIP) is a central regulator to initiate DNA end resection and homologous recombination (HR). Several studies have shown that post-translational modifications control the activity or expression of CtIP. However, it remains unclear whether and how cells restrain CtIP activity in unstressed cells and activate CtIP when needed. Here, we identify that USP52 directly interacts with and deubiquitinates CtIP, thereby promoting DNA end resection and HR. Mechanistically, USP52 removes the ubiquitination of CtIP to facilitate the phosphorylation and activation of CtIP at Thr-847. In addition, USP52 is phosphorylated by ATM at Ser-1003 after DNA damage, which enhances the catalytic activity of USP52. Furthermore, depletion of USP52 sensitizes cells to PARP inhibition in a CtIP-dependent manner in vitro and in vivo. Collectively, our findings reveal the key role of USP52 and the regulatory complexity of CtIP deubiquitination in DNA repair.

Highlights

Human C-terminal binding protein (CtBP)–interacting protein (CtIP) is a central regulator to initiate DNA end resection and homologous recombination (HR)
We examined the effect of USP52 on the two major DNA repair pathways and found that USP52 depletion decreased the efficiency of HR− but not nonhomologous end-joining (NHEJ)-based DNA repair (Fig. 2j and Supplementary Fig. 2c)
Expression of CtIP 2KR but not WT CtIP rescued defective CtIP–T847 phosphorylation in USP52-deficient cells (Fig. 4h). These results suggest that the ubiquitination of CtIP negatively regulates its phosphorylation at Thr-847 and biological functions; USP52 removes the inhibitory ubiquitination of CtIP to promote DNA end resection and HR following DNA damage

Summary

Introduction

Human C-terminal binding protein (CtBP)–interacting protein (CtIP) is a central regulator to initiate DNA end resection and homologous recombination (HR). NHEJ is a highly error-prone DNA repair mechanism functioning throughout the cell cycle that directly ligates broken DNA ends in the absence of sequence homology. Terminal binding protein (CtBP) interacting protein (CtIP) is essential for the initiation of DNA end resection. Besides its role in DNA end resection, CtIP interacts with other proteins including retinoblastoma protein and breast cancer 1 (BRCA1) to regulate cell cycle progression in both a transcription dependent and independent manner[14,15]. RNF8/RNF168 pathway-dependent ubiquitination has an essential role in recruiting signaling and repair factors including 53BP1 and RAP80 to DSB sites[23,24]. CtIP is ubiquitinated by APC/CCdh[1] and RNF138 to regulate its stability and retention at DSB sites, respectively[25,26]

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