title: Distal regulatory element of the STAT1 gene potentially mediates positive feedback control of STAT1 expression.
abstract: We previously identified a distal regulatory element located approximately 5.5-kb upstream of the signal transducer and activator of transcription 1 (STAT1) gene, thereafter designating it as 5.5-kb upstream regulatory region (5.5URR). In this study, we investigated the functional roles of 5.5URR in the transcriptional regulation of STAT1 gene. A chromosome conformation capture assay indicated physical interaction of 5.5URR with the STAT1 core promoter. In luciferase reporter assays, 5.5URR-combined STAT1 core promoter exhibited significant increase in reporter activity enhanced by forced STAT1 expression or interferon (IFN) treatment, but STAT1 core promoter alone did not. The 5.5URR contained IFN-stimulated response element and GAS sites, which bound STAT1 complexes in electrophoretic mobility shift assays. Consistently, chromatin immunoprecipitation (ChIP) assays of HEK293 cells with Halo-tagged STAT1 expression indicated the association of Halo-tagged STAT1 with 5.5URR. ChIP assays with IFN treatment demonstrated that IFNs promoted the recruitment of Halo-tagged STAT1 to 5.5URR. Forced STAT1 expression or IFN treatment increased the expression of endogenous STAT1 and other IFN signaling pathway components, such as STAT2, IRF9 and IRF1, besides IFN-responsive genes. Collectively, the results suggest that 5.5URR may provide a regulatory platform for positive feedback control of STAT1 expression possibly to amplify or sustain the intracellular IFN signals.
authors.affiliation: Department of Anatomy and Cell Biology, Research Institute of Pharmaceutical Science, Faculty of Pharmacy, Musashino University, Nishitokyo, Tokyo, 202-8585, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Yuasa
authors.affiliation: Department of Anatomy and Cell Biology, Research Institute of Pharmaceutical Science, Faculty of Pharmacy, Musashino University, Nishitokyo, Tokyo, 202-8585, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Hijikata
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D025461:Feedback, Physiological; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D050856:Interferon Regulatory Factor-1 / Q000378:metabolism; D007372:Interferons / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D050794:STAT1 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics
chemical_list: D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D050794:STAT1 Transcription Factor; D007372:Interferons