title: DNA-damage tolerance mediated by PCNA*Ub fusions in human cells is dependent on Rev1 but not Polη.
abstract: In response to replication-blocking lesions, proliferating cell nuclear antigen (PCNA) can be sequentially ubiquitinated at the K164 residue, leading to two modes of DNA-damage tolerance, namely, translesion DNA synthesis (TLS) and error-free lesion bypass. Although the majority of reported data support a model whereby monoubiquitinated PCNA enhances its affinity for TLS polymerases and hence recruits them to the damage sites, this model has also been challenged by several observations. In this study, we expressed the PCNA-164R and ubiquitin (UB) fusion genes in an inducible manner in an attempt to mimic PCNA monoubiquitination in cultured human cells. It was found that expression of both N- and C-terminal PCNA•Ub fusions conferred significant tolerance to ultraviolet (UV)-induced DNA damage. Surprisingly, depletion of Polη, a TLS polymerase dedicated to bypassing UV-induced pyrimidine dimers, did not alter tolerance conferred by PCNA•Ub. In contrast, depletion of Rev1, another TLS polymerase serving as a scaffold for the assembly of the TLS complex, completely abolished PCNA•Ub-mediated damage tolerance. Similar genetic interactions were confirmed when UV-induced monoubiquitination of endogenous PCNA is abolished by RAD18 deletion. Hence, PCNA•Ub fusions bypass the requirement for PCNA monoubiquitination, and UV damage tolerance conferred by these fusions is dependent on Rev1 but independent of Polη.
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China, Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon S7N 5E5, Canada and Project for Environmental Dynamics and Radiation Effects, Fukushima Project Headquarters, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
authors.forename: Zhoushuai
authors.initials: Z
authors.lastname: Qin
authors.forename: Mengxue
authors.initials: M
authors.lastname: Lu
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Michelle
authors.initials: M
authors.lastname: Hanna
authors.forename: Naoko
authors.initials: N
authors.lastname: Shiomi
authors.forename: Wei
authors.initials: W
authors.lastname: Xiao
mesh_terms: D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism*; D004843:Epistasis, Genetic; D050939:Gene Fusion; D045325:HCT116 Cells; D057809:HEK293 Cells; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D011740:Pyrimidine Dimers / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D009687:Nuclear Proteins; D009713:Nucleotidyltransferases; D018809:Proliferating Cell Nuclear Antigen; D011740:Pyrimidine Dimers; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; C485954:RAD18 protein, human; C429004:REV1 protein, human; D000099270:Y-Family DNA Polymerases