C/EBPdelta and C/EBPgamma bind the CCAAT-box in the human beta-globin promoter and modulate the activity of the CACC-box binding protein, EKLF.

Developmental- and tissue-specific expression of globin genes is mediated by a few key elements within the proximal promoter of each gene. DNA-binding assays previously identified NF-Y, GATA-1, C/EBPbeta and C/EBPgamma as candidate regulators of beta-globin transcription via the CCAAT-box, a promoter element situated between CACC- and TATA-boxes. We have identified C/EBPdelta as an additional beta-globin CCAAT-box binding protein. In reporter assays, we show that C/EBPdelta can co-operate with EKLF, a CACC-box binding protein, to activate the beta-globin promoter, whereas C/EBPgamma inhibits the transcriptional activity of EKLF in this assay.