RNF126 Quenches RNF168 Function in the DNA Damage Response

Lianzhong Zhang,Zhenzhen Wang,Ruifeng Shi,Xuefei Zhu,Jiahui Zhou,Bin Peng,Xingzhi Xu

doi:10.1016/j.gpb.2018.07.004

Abstract

DNA damage response (DDR) is essential for maintaining genome stability and protecting cells from tumorigenesis. Ubiquitin and ubiquitin-like modifications play an important role in DDR, from signaling DNA damage to mediating DNA repair. In this report, we found that the E3 ligase ring finger protein 126 (RNF126) was recruited to UV laser micro-irradiation-induced stripes in a RNF8-dependent manner. RNF126 directly interacted with and ubiquitinated another E3 ligase, RNF168. Overexpression of wild type RNF126, but not catalytically-inactive mutant RNF126 (CC229/232AA), diminished ubiquitination of H2A histone family member X (H2AX), and subsequent bleomycin-induced focus formation of total ubiquitin FK2, TP53-binding protein 1 (53BP1), and receptor-associated protein 80 (RAP80). Interestingly, both RNF126 overexpression and RNF126 downregulation compromised homologous recombination (HR)-mediated repair of DNA double-strand breaks (DSBs). Taken together, our findings demonstrate that RNF126 negatively regulates RNF168 function in DDR and its appropriate cellular expression levels are essential for HR-mediated DSB repair.

Highlights

Genomic DNA is under continuous assault by various environmental and endogenous factors that cause DNA damage, including UV radiation from sunlight and free radicals derived from intermediate metabolites
To determine if ring finger protein 126 (RNF126) recruitment to the DNA damage stripe is dependent on the catalytic activity of ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3-related protein (ATR), DNAdependent protein kinase catalytic subunit (DNA-PKcs), or poly [ADP-ribose] polymerase 1 (PARP1), U2OS cells expressing GFP-RNF126 was pre-treated with specific inhibitor respectively
We found that both ATM inhibitor and PARP inhibitor efficiently diminished recruitment of GFP-RNF126 to the DNA damage stripes, whereas neither ATR inhibitor nor DNA-PKcs inhibitor had such an effect (Figure S1), suggesting that RNF126 recruitment to the DNA damage site is dependent on ATM and PARP

Summary

Introduction

Genomic DNA is under continuous assault by various environmental and endogenous factors that cause DNA damage, including UV radiation from sunlight and free radicals derived from intermediate metabolites. A comprehensive DNA damage response (DDR) network has evolved that can repair damaged DNA, maintain genome stability, and protect cells from tumorigenesis [1,2,3]. Production and hosting by Elsevier B.V. on behalf of Beijing Institute of Genomics, Chinese Academy of Sciences and Genetics Society of China. Deliberate induction of DNA damage via radiation therapy or exposure to certain chemotherapeutic agents is a valuable strategy to cause irreparable DNA damage and promote cancer cell death [4,5]. Fully understanding the mechanisms that underlie the DDR network will help delineate the molecular mechanisms underlying tumorigenesis, determine measures of cancer prevention, and develop novel and effective cancer therapies

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Results

Conclusion