JPO1/CDCA7, a novel transcription factor E2F1-induced protein, possesses intrinsic transcriptional regulator activity.

JPO1/CDCA7 was originally identified as a c-Myc-responsive gene that participates in neoplastic transformation. Here, we report the identification of JPO1/CDCA7 as a direct transcriptional target of transcription factor E2F1. We demonstrated that overexpression of E2F1 by adenoviral-mediated gene transfer upregulated JPO1/CDCA7 mRNA expression in human cells. Analysis of human and mouse JPO1/CDCA7 promoter constructs showed that an E2F-responsive sequence was necessary for E2F1-induced activation of the JPO1/CDCA7 gene transcription. Among the members of the E2F family, E2F1 to E2F4, but not E2F5 or E2F6, activated the JPO1/CDCA7 reporter construct. Chromatin immunoprecipitation analysis demonstrated that E2F1, E2F2, and E2F4 specifically bound to an E2F-responsive sequence of the human JPO1/CDCA7 gene. Like JPO2/R1, which has a homologous transcriptional regulator domain, the C-terminal cysteine-rich region of JPO1/CDCA7 protein induced transcriptional activity in a mammalian one-hybrid assay. Taken together, our results suggest that JPO1/CDCA7 is a unique transcription regulator whose expression is activated by E2F1 as well as c-Myc.