CCAAT/Enhancer-Binding Protein ε Antagonism of GATA-1 Transcriptional Activity in the Eosinophil Is Mediated by a Unique N-Terminal Repression Domain, Is Independent of Sumoylation and Does Not Require DNA Binding.

CCAAT/enhancer binding protein epsilon (C/EBPε) is required for eosinophil differentiation, lineage-specific gene transcription, and expression of C/EBPε and shorter 27kD and 14kD isoforms is developmentally regulated during this process. We previously defined the 27kD isoform (C/EBPε) as an antagonist of GATA-1 transactivation of the eosinophil's major basic protein-1 (MBP1) P2-promoter, showing C/EBPε and GATA-1 physically interact. In the current study, we used a Tat-C/EBPε fusion protein for cell/nuclear transduction of an eosinophil myelocyte cell line to demonstrate that C/EBPε is a potent repressor of MBP1 transcription.