Abstract 3367: USP7 regulates CSB protein recovery after UV-induced DNA damage

Abstract

Abstract Cockayne syndrome group B (CSB) protein functions in transcription-coupled repair (TCR), a sub-pathway of nucleotide excision repair (NER). We previously demonstrated that ultraviolet radiation (UVR) induces a valosin-containing protein (VCP)/p97-dependent ubiquitin-mediated CSB degradation. In this study, we further revealed that CSB protein is ubiquitinated immediately after ultraviolet-light irradiation and undergoes proteasomal degradation. The recovery of CSB protein level is dependent on USP7. Disruption of USP7 function sensitizes CSB degradation to lower UVR doses. We further demonstrated USP7's interaction with CSB in vivo by immunoprecipitation and in vitro by GST pulldown assays. Interestingly, in vitro CSB strongly binds to TRAF domain, which also interacts with UV stimulated scaffold protein A (UVSSA). Additionally, USP7 also interacts with VCP/p97 using its TRAF domain and C-terminal in in vitro. Furthermore, VCP/p97 was demonstrated to associates with USP7 in vivo. These results suggest that USP7 rescues CSB from ubiquitin-mediated proteolysis after (VCP)/p97-mediated CSB extraction from chromatin, preventing the CSB-ubiquitin conjugates being presented to proteasome for degradation. Citation Format: Shengcai Wei. USP7 regulates CSB protein recovery after UV-induced DNA damage [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 3367.