title: Rad18 is a transcriptional target of E2F3.
abstract: The E2F family of transcription factors responds to a variety of intracellular and extracellular signals and, as such, are key regulators of cell growth, differentiation and cell death. The cellular response to DNA damage is a multistep process generally involving the initial detection of DNA damage, propagation of signals via posttranslational modifications (e.g., phosphorylation and ubiquitination) and, finally, the implementation of a response. We have previously reported that E2F3 can be induced by DNA damage, and that it plays an important role in DNA damage-induced apoptosis. Here, we demonstrate that E2F3 knockdown compromises two canonical DNA damage modification events, the ubiquitination of H2AX and PCNA. We find that the defect in these posttranscriptional modifications after E2F3 knockdown is due to reduced expression of important DNA damage responsive ubiquitin ligases. We characterized the regulation of one of these ligases, Rad18, and we demonstrated that E2F3 associates with the Rad18 promoter and directly controls its activity. Furthermore, we find that ectopic expression of Rad18 is sufficient to rescue the PCNA ubiquitination defect resulting from E2F3 knockdown. Our study reveals a novel facet of E2F3's control of the DNA damage response.
authors.affiliation: Department of Biochemistry and University of Mississippi Cancer Institute, University of Mississippi Medical Center, Jackson, MS, USA.
authors.forename: Lakshman
authors.initials: L
authors.lastname: Varanasi
authors.forename: Phi M
authors.initials: PM
authors.lastname: Do
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Goluszko
authors.forename: Luis A
authors.initials: LA
authors.lastname: Martinez
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D050699:E2F3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D059585:G1 Phase Cell Cycle Checkpoints; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination
chemical_list: D004268:DNA-Binding Proteins; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D050699:E2F3 Transcription Factor; C098319:E2F3 protein, human; C468783:H2AX protein, human; D006657:Histones; D018809:Proliferating Cell Nuclear Antigen; C485954:RAD18 protein, human; D034741:RNA, Small Interfering; D044767:Ubiquitin-Protein Ligases; D002945:Cisplatin