USP11 suppresses CHK1 activation by deubiquitinating CLASPIN

Hongchang Zhao,Ji Liao,Min Zhu,Zhifeng Wang,Xingzhi Xu

doi:10.1007/s42764-021-00034-1

Abstract

CLASPIN is an essential mediator of ATR-dependent CHK1 activation in the DNA replication checkpoint. K6-linked polyubiquitination of CLASPIN promotes its chromatin loading and subsequent CHK1 activation. Here, we found that ubiquitin-specific protease 11 (USP11) deubiquitinates the K6-linkage polyubiquitinated form of CLASPIN. Under steady-state conditions, USP11 interacts with CLASPIN, reducing CLASPIN K6-linked ubiquitination levels. In response to replication stress, USP11 is phosphorylated by ATR and subsequently disassociated from CLASPIN, promoting CLASPIN chromatin loading, CHK1 activation and ultimately genome stability. Taken together, our findings uncover a novel function of USP11 in negatively regulating CHK1 activation by suppressing CLASPIN chromatin loading.

Highlights

The ATR–CHK1 pathway has key roles in maintaining genome stability and integrity during DNA replication (Berti et al 2020; Menolfi and Zha 2020; Yazinski and Zou 2016)
In a candidate screen for ubiquitin-specific proteases (USPs) in regulating replication stress-induced CHK1 activation, we previously identified that ubiquitin-specific protease 20 (USP20) promotes CHK1 activation by deubiquitinating CLASPIN and enhancing its protein stability (Zhu et al 2014)
CPT is an inhibitor of DNA topoisomerase I (Topo I) that binds to the Topo I and DNA complex and stabilizes it, thereby triggering the replication stress response by activating the ATR–CHK1 signaling cascade

Summary

Introduction

The ATR (ataxia telangiectasia and Rad3-related protein)–CHK1 (checkpoint kinase 1) pathway has key roles in maintaining genome stability and integrity during DNA replication (Berti et al 2020; Menolfi and Zha 2020; Yazinski and Zou 2016). We and others have demonstrated that the E3 ligase HERC2 and the ubiquitin-specific protease 20 (USP20) coordinate CHK1 activation by modulating CLASPIN stability (Wang et al 2017; Yuan et al 2014; Zhu et al 2014). We found that USP11 elicits its non-proteasome-mediated degradation effects by enzymatically removing K6-linked polyubiquitin chains from CLASPIN. In this way, CLASPIN chromatin loading and subsequent CHK1 activation are negatively regulated in response to replication stress

Results

Discussion

Experimental procedures