title: Direct repression of the human IRF-3 promoter by E2F1.
abstract: Interferon regulatory factor 3 (IRF-3) plays an important role in virus and double-stranded RNA-mediated induction of type I interferon and RANTES, DNA damage signaling, tumor suppression, and virus-induced apoptosis. However, cis elements or trans factors responsible for regulating IRF-3 expression remain largely unknown. Here we report that the transcription factor E2F1 negatively regulates the basal transcriptional activity of IRF-3 and deregulates IRF-3 expression at mRNA level. By transient transfection analysis, we demonstrate that the mutation of E2F-binding site results in a profound promotion of IRF-3 promoter activity. Overexpression of E2F1, but not a mutant E2F1, represses the IRF-3 promoter activity in reporter gene assays while knocking down of endogenous E2F1 by shRNA strategy results in enhanced IRF-3 promoter activity. Electrophoretic gel mobility shift assays and antibody competition assays confirm that E2F1 protein binds to the E2F consensus binding site in the IRF-3 promoter. Chromatin immunoprecipitation assays demonstrate that E2F1 interacts with the IRF-3 promoter in vivo. These results suggest that E2F1 negatively regulates IRF-3 transcription through binding to the E2F consensus binding site.
authors.affiliation: Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, 300 Guang Zhou Road, Nanjing, Jiangsu Province 210029, China.
authors.forename: Hua-Guo
authors.initials: HG
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Ren
authors.forename: Li
authors.initials: L
authors.lastname: Zou
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Rui
authors.initials: R
authors.lastname: Jin
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Zhou
mesh_terms: D047369:Chromatin Immunoprecipitation; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000235:genetics*; D009154:Mutation; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; D012097:Repressor Proteins