CDCA4 is an E2F transcription factor family-induced nuclear factor that regulates E2F-dependent transcriptional activation and cell proliferation.
The TRIP-Br1/p34(SEI-1) family proteins participate in cell cycle progression by coactivating E2F1- or p53-dependent transcriptional activation. Here, we report the identification of human CDCA4 (also know as SEI-3/Hepp) as a novel target gene of transcription factor E2F and as a repressor of E2F-dependent transcriptional activation. Analysis of CDCA4 promoter constructs showed that an E2F-responsive sequence in the vicinity of the transcription initiation site is necessary for the E2F1-4-induced activation of CDCA4 gene transcription. Chromatin immunoprecipitation analysis demonstrated that E2F1 and E2F4 bound to an E2F-responsive sequence of the human CDCA4 gene. Like TRIP-Br1/p34(SEI-1) and TRIP-Br2 (SEI-2), the transactivation domain of CDCA4 was mapped within C-terminal acidic region 175-241. The transactivation function of the CDCA4 protein was inhibited by E2F1-4 and DP2, but not by E2F5-8. Inhibition of CDCA4 transactivation activity by E2F1 partially interfered with retinoblastoma protein overexpression. Conversely, CDCA4 suppressed E2F1-3-induced reporter activity. CDCA4 (but not acidic region-deleted CDCA4) suppressed E2F1-regulated gene promoter activity. These findings suggest that the CDCA4 protein functions as a suppressor at the E2F-responsive promoter. Small interfering RNA-mediated knockdown of CDCA4 expression in cancer cells resulted in up-regulation of cell growth rates and DNA synthesis. The CDCA4 protein was detected in several human cells and was induced as cells entered the G1/S phase of the cell cycle. Taken together, our results suggest that CDCA4 participates in the regulation of cell proliferation, mainly through the E2F/retinoblastoma protein pathway.
Hayashi
Reiko
R
Laboratory of Molecular and Cellular Biology, Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashimita, Kawasaki, Kanagawa 214-8571, Japan.
Goto
Yuya
Y
Ikeda
Ryuji
R
Yokoyama
Kazunari K
KK
Yoshida
Kenichi
K
D000595:Amino Acid Sequence; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D049109:Cell Proliferation; D050684:E2F Transcription Factors / Q000378:metabolism / Q000502:physiology*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016160:Retinoblastoma Protein / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D015533:Transcriptional Activation
C515965:CDCA4 protein, human; D018797:Cell Cycle Proteins; D050684:E2F Transcription Factors; D016160:Retinoblastoma Protein