PARP1-mediated PARylation of TonEBP prevents R-loop–associated DNA damage

Byeong Jin Ye,Hyun Je Kang,Whaseon Lee-Kwon,Hyug Moo Kwon,Soo Youn Choi

doi:10.1016/j.dnarep.2021.103132

Abstract

Lack of coordination between the DNA replication and transcription machineries can increase the frequency of transcription–replication conflicts, leading ultimately to DNA damage and genomic instability. A major source of these conflicts is the formation of R-loops, which consist of a transcriptionally generated RNA–DNA hybrid and the displaced single-stranded DNA. R-loops play important physiological roles and have been implicated in human diseases. Although these structures have been extensively studied, many aspects of R-loop biology and R-loop–mediated genome instability remain unclear. We found that in cancer cells, tonicity-responsive enhancer-binding protein (TonEBP, also called NFAT5) interacted with PARP1 and localized to R-loops in response to DNA-damaging agent camptothecin (CPT), which is associated with R-loop formation. PARP1-mediated PARylation was required for recruitment of TonEBP to the sites of R-loop–associated DNA damage. Loss of TonEBP increased levels of R-loop accumulation and DNA damage, and promoted cell death in response to CPT. These findings suggest that TonEBP mediates resistance to CPT-induced cell death by preventing R-loop accumulation in cancer cells.

Highlights

Maintenance of genome integrity depends on spatiotemporal coor dination between the DNA replication and transcription machineries
Con structs containing the Rel-homology domain (RHD), including full-length Tonicity-responsive enhancer-binding protein (TonEBP) and Yc1 (N terminus of TonEBP), interacted with poly (ADP-ribose) polymerase 1 (PARP1), whereas a mutant lacking the RHD (ΔRHD) did not (Fig. 1D), indicating that the RHD of TonEBP is essential for its interaction with PARP1
These data indicate that the RHD of TonEBP and the catalytic domain (CatD) of PARP1 mediate the interaction between the two proteins

Summary

Introduction

Maintenance of genome integrity depends on spatiotemporal coor dination between the DNA replication and transcription machineries Lack of such coordination can lead to DNA damage and genomic instability resulting from an elevated frequency of tran scription–replication conflicts [1,2]. R-loops, which arise naturally during transcription in organisms from bacteria to mammals, play multiple roles in cellular processes, including regulation of gene expression [4], transcription termination [5], and DNA replication [6]. In addition to these physiological functions, R-loops threaten genome integrity, resulting in deleterious effects on the cell [7,8,9]. R-loops must be tightly regulated in living cells

Methods

Results

Conclusion