Identification and characterization of the promoter of human ATF5 gene.

ATF5, a member of ATF/CREB family of b-ZIP transcription factors, is highly expressed in a wide variety of neoplasms and regulates cell differentiation, cell survival and apoptosis. However, the mechanism of human ATF5 transcriptional regulation has not been clarified. Here, we identified the transcription start site of the ATF5 gene, cloned its 5'-flanking region and identified the region -105 to +3 relative to the transcription start site as that having promoter activity. This region contained potential binding sites for several transcription factors, including EBF1, Sp1 and E2F1. EBF1 transcription factor binds to the ATF5 promoter and regulates the ATF5 transcription in an EBF-binding site independent manner. Thus, our studies not only provided molecular basis of ATF5 transcriptional regulation, but also identified ATF5 as a target gene of EBF1 transcription factor.