CDF-1, a Novel E2F-Unrelated Factor, Interacts With Cell Cycle-Regulated Repressor Elements in Multiple Promoters

• Published in: Nucleic acids research 1997-12, Vol.25 (24), p.4915-4920
• Main Authors: Liu, Ningshu, Lucibello, Frances C., Körner, Kathrin, Wolfraim, Lawrence A., Zwicker, Jörk, Müller, Rolf
• Format: Article
• Language: English
• Subjects: 3T3 Cells; Animals; Carrier Proteins; CDC2 Protein Kinase - biosynthesis; CDC2 Protein Kinase - genetics; cdc25 Phosphatases; Cell Cycle - genetics; Cell Cycle Proteins - biosynthesis; Cell Cycle Proteins - genetics; Cyclin A - biosynthesis; Cyclin A - genetics; DNA Footprinting; DNA-Binding Proteins - physiology; E2F Transcription Factors; Gene Expression Regulation - genetics; Macromolecular Substances; Mice; Phosphoprotein Phosphatases - biosynthesis; Phosphoprotein Phosphatases - genetics; Promoter Regions, Genetic; Repressor Proteins - physiology; Retinoblastoma-Binding Protein 1; Transcription Factor DP1; Transcription Factors - metabolism; Transfection
• ISSN: 0305-1048; 1362-4962; 1362-4962
• DOI: 10.1093/nar/25.24.4915

The cdc25C, cdc2 and cyclin A promoters are controlled by transcriptional repression through two contiguous protein binding sites, termed the CDE and CHR. In the present study we have identified a factor, CDF-1, which interacts with the cdc25C CDE-CHR module. CDF-1 binds to the CDE in the major groove and to the CHR in the minor grove in a cooperative fashion in vitro, in a manner similar to that seen by genomic footprinting. In agreement with in vivo binding data and its putative function as a periodic repressor, DNA binding by CDF-1 in nuclear extracts is down-regulated during cell cycle progression. CDF-1 also binds avidly to the CDE-CHR modules of the cdc2 and cyclin A promoters, but not to the E2F site in the B-myb promoter. Conversely, E2F complexes do not recognize the cdc25C CDE-CHR and CDF-1 is immunologically unrelated to all known E2F and DP family members. This indicates that E2F- and CDF-mediated repression is controlled by different factors acting at different stages during the cell cycle. While E2F-mediated repression seems to be associated with genes that are up-regulated early (around mid G1), such as B-myb, CDE-CHR-controlled genes, such as cdc25C, cdc2 and cyclin A, become derepressed later. Finally, the fractionation of native nuclear extracts on glycerol gradients leads to separation of CDF-1 from both E2F complexes and pocket proteins of the pRb family. This emphasizes the conclusion that CDF-1 is not an E2F family member and points to profound differences in the cell cycle regulation of CDF-1 and E2F.