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Human IL1B gene induction requires transcription factor‐mediated DNA looping
Author(s) -
Wang Kent Z.Q.,
Unlu Sebnem,
Adamik Juraj,
Su AnJey,
Auron Philip E.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.487.6
Subject(s) - enhancer , transcription factor , promoter , gene , response element , transcription (linguistics) , microbiology and biotechnology , biology , dna , gene expression , luciferase , chemistry , transfection , genetics , linguistics , philosophy
Human IL1B gene transcription is regulated by a core promoter along with a 2.8 kbp upstream induction sequence (UIS) enhancer which generates potent monocyte‐specific LPS‐dependent activity. Several approaches were used to investigate how these two distant sequences cooperate in IL1B gene induction. These included the use of non‐monocytic cells with ectopically expressed putatively relevant transcription factors, as well as monocytes, in order to assay the levels of mRNA expression from the endogenous IL1B gene and the activities of human IL1B promoter‐driven luciferase reporters. Consistent with earlier studies, our data reveal that Spi‐1 is the most important factor, demonstrating a dose‐dependant induction of IL1B . Ectopic expression of other transcription factors such as C/EBPβ, IRF8 and NF‐κB cooperatively enhance the effect of suboptimal Spi‐1, especially in the presence of dominant‐positive TRAF6 acting as a TLR4/IL1R surrogate. The results argue for the importance of constitutive Spi‐1 and activated NF‐κB and C/EBPβ in supporting IL1B induction. Investigation of LPS‐dependent genomic DNA conformation in monocytes reveals an inducible loop between the enhancer and promoter. Furthermore, the DNA loop may be a critical element in IL1B induction and is hypothesized to involve a Spi‐1 interaction at the promoter with C/EBPβ at the UIS.