The mammalian transcriptional repressor RBP (CBF1) regulates interleukin-6 gene expression

The cellular interleukin-6 (IL-6) gene contains a target site for the mammalian transcriptional repressor RBP. The target site is contained within the interleukin response element (ILRE), which mediates IL-6 activation by NF-kappa B. In this study, we show by using transient-expression assays that RBP represses activated transcription from the IL-6 gene. The presence and position of the RBP target site are crucial in mediating repression by RBP. While RBP binds within the ILRE, it does not target NF-kappa B alone; nonetheless, NF-kappa B binding to the ILRE is required for repression. Our results indicate that RBP represses coactivation by NF-kappa B and another cellular transcription factor, C/EBP-beta.