title: E2F1 regulates the base excision repair gene XRCC1 and promotes DNA repair.
abstract: The E2F1 transcription factor activates S-phase-promoting genes, mediates apoptosis, and stimulates DNA repair through incompletely understood mechanisms. XRCC1 (x-ray repair cross-complementing group 1) protein is important for efficient single strand break/base excision repair. Although both damage and proliferative signals increase XRCC1 levels, the mechanisms regulating XRCC1 transcription remain unclear. To study these upstream mechanisms, the XRCC1 promoter was cloned into a luciferase reporter. Ectopic expression of wild-type E2F1, but not an inactive mutant E2F1(132E), activated the XRCC1 promoter-luciferase reporter, and deletion of predicted E2F1 binding sites in the promoter attenuated E2F1-induced activation. Endogenous XRCC1 expression increased in cells conditionally expressing wild-type, but not mutant E2F1, and methyl methanesulfonate-induced DNA damage stimulated XRCC1 expression in E2F1(+/+) but not E2F1(-/-) mouse embryo fibroblasts (MEFs). Additionally, E2F1(-/-) MEFs displayed attenuated DNA repair after methyl methanesulfonate-induced damage compared with E2F1(+/+) MEFs. Moreover, Chinese hamster ovary cells with mutant XRCC1 (EM9) were more sensitive to E2F1-induced apoptosis compared with Chinese hamster ovary cells with wild-type XRCC1 (AA8). These results provide new mechanistic insight into the role of the E2F pathway in maintaining genomic stability.
authors: Department of Medicine, Division of Hematology and Medical Oncology, Oregon Health and Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239, USA.
authors: Dexi
authors: D
authors: Chen
authors: Zhiyong
authors: Z
authors: Yu
authors: Zhiyi
authors: Z
authors: Zhu
authors: Charles D
authors: CD
authors: Lopez
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001483:Base Sequence / Q000235:genetics; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D042822:Genomic Instability / Q000187:drug effects / Q000502:physiology; D008698:Mesylates / Q000494:pharmacology; D051379:Mice; D020218:Response Elements / Q000187:drug effects / Q000502:physiology*; D016196:S Phase / Q000187:drug effects / Q000502:physiology*; D017384:Sequence Deletion; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D004268:DNA-Binding Proteins; D050687:E2F1 Transcription Factor; C493754:E2f1 protein, mouse; D008698:Mesylates; D000076105:X-ray Repair Cross Complementing Protein 1; C000619352:Xrcc1 protein, mouse; C045880:methanesulfonic acid