Cell cycle regulation of the murine cdc25B promoter - Essential role for nuclear factor-Y and a proximal repressor element

Expression of the cdc25B gene is up-regulated late during cell cycle progre ssion (S/G(2)). We have cloned the murine cdc25B promoter to identify eleme nts involved in transcriptional regulation. A detailed structure-function a nalysis led to the identification of several elements that are located upst ream of a canonical Inr motif at the site of transcription initiation and a re involved in transcriptional activation and regulation. Activation of the promoter is largely mediated by NF-Y and Sp1/3 interacting with one and fo ur proximal binding sites, respectively. In addition, NF-Y plays an essenti al role in cell cycle regulation in conjunction with a repressor element (c ell cycle-regulated repressor) located similar to 30 nucleotides upstream o f the putative Inr element and overlapping a consensus TATA motif. The cell cycle-regulated repressor is unrelated to the previously described cell cy cle-regulated repressor elements. Taken together, our observations suggest that expression of the cdc25B gene is controlled through a novel mechanism of cell cycle-regulated transcription.