The role of Stat and C/EBP transcription factors in the synergistic activation of rat serine protease inhibitor-3 gene by interleukin-6 and dexamethasone.
The rat serine proteinase inhibitor 3 gene is activated by interleukin 6 (IL-6) and glucocorticoids in hepatic cells. We report here that a 147 bp promoter is sufficient for both IL-6 stimulation and glucocorticoid enhancement of IL-6 induced transcription. Within this region we identified two functional elements binding transcription factors from the C/EBP (CCAAT/enhancer binding proteins) and Stat (signal transducers and activators of transcription) families. Mutations introduced into the Stat binding site resulted in a loss of responsiveness, showing that this element is indispensable for activation. In contrast, the promoter containing the mutated C/EBP binding site was still responsive to IL-6 and glucocorticoids; however, the magnitude of the induction was decreased by 50%. The Stat binding element is an enhancer capable of conferring both responsiveness to IL-6 and partial enhancement of glucocorticoids on to a heterologous promoter. In response to IL-6 this element rapidly binds acute-phase response factor (APRF/Stat3) and, later, the protein(s) that require ongoing protein synthesis and is recognized by anti-Stat3 antibodies. In addition, long-term treatment with IL-6 results in sustained phosphorylation of APRF /Stat3.
Kordula
T
T
Institute of Molecular Biology, Jagiellonian University, Krakow, Poland.
Travis
J
J
D000209:Acute-Phase Proteins / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D051381:Rats; D050796:STAT3 Transcription Factor; D015842:Serine Proteinase Inhibitors / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection
D000209:Acute-Phase Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D015850:Interleukin-6; D009687:Nuclear Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015842:Serine Proteinase Inhibitors; C494088:Stat3 protein, rat; D015534:Trans-Activators; D014157:Transcription Factors; D003907:Dexamethasone