TonEBP mediates PCNA polyubiquitination on DNA damage sites via interaction with SHPRH and USP1

PCNA ubiquitination is important for DNA damage tolerance in eukaryotic replication. While PCNA monoubiquitination activates a mutagenic translesion synthesis pathway, polyubiquitination activates an error-free template switching for DNA damage bypass. Even though PCNA polyubiquitination is critical for the maintenance of genomic integrity, underlying mechanisms are poorly understood. Here, we report that TonEBP (tonicity-responsive enhancer binding protein) is involved the PCNA polyubiquitination in response to DNA damage. TonEBP sequentially recruited an E3 ubiquitin ligase SHPRH followed by a deubiquitinase USP1 into DNA damaged sites, which showed direct correlation with dynamics of PCNA polyubiquitination. The Rel-homology domain (RHD) of TonEBP, which encircles DNA, was required for the interaction with SHRPH and USP1. Consistent with its importance for DNA damage bypass, knockdown or deletion of RHD in TonEBP increased sensitivity to methyl methanesulfonate. Collectively, TonEBP is a key player in the post-replication DNA repair. Citation Format: Hyunje Kang, Hyun Park, Eun Jin Yoo, Jun Ho Lee, Soo Youn Choi, Whaseon Lee-Kwon, Kyoo-young Lee, Jin-Hoe Hur, Jeong Kon Seo, Kyungjae Myung, Hyug Moo Kwon. TonEBP mediates PCNA polyubiquitination on DNA damage sites via interaction with SHPRH and USP1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1354.