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

The nuclear protein CBF1 has been shown to function as an intermediate to target transcription factors,such as the activated Notch receptor,to specific DNA sites. In this paper,we show that CBF1 from cell lines of different origin is able to bind to the[kappa]B site of the IL-6 promoter. By transfection 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 sequencessurrounding the recognition site. Furthermore,we show that CBF1 induces DNA bending. This finding suggests that CBF1 may influence IL-6 gene transcription by determining a specific conformation of the promoter region.