Interaction of the nuclear protein CBF1 with the kappa B Site of the IL-6 gene promoter

The nuclear protein CBF1 has been shown to function as an intermediate to t arget transcription factors, such as the activated Notch receptor, to speci fic DNA sites, In this paper, we show that CBF1 from cell lines of differen t origin is able to bind to the kappa B site Of the IL-6 promoter. By trans fection analyses performed in HeLa cells, we demonstrate that overexpressed CBF1 acts as a negative regulator of IL-6 gene transcription and is unable to elicit Notch-dependent activation of this gene. Analyses of protein-DNA interactions indicate that the topology of the complex formed by CBF1 and the target DNA is subtly affected by sequences surrounding the recognition site. Furthermore, we show that CBF1 induces DNA bending. This finding sugg ests that CBF1 may influence IL-6 gene transcription by determining a speci fic conformation of the promoter region.