Cooperative Activities of Hematopoietic Regulators Recruit RNA Polymerase II to a Tissue-Specific Chromatin Domain

The hematopoietic transcription factor GATA-1 regulates erythropoiesis and β-globin expression. Although consensus GATA-1 binding sites exist throughout the murine β-globin locus, we found that GATA-1 discriminates among these sites in vivo. Conditional expression of GATA-1 in GATA-1-null cells recapitulated the occupancy pattern. GATA-1 induced RNA polymerase II (pol II) recruitment to subregions of the locus control region and to the β-globin promoters. The hematopoietic factor NF-E2 cooperated with GATA-1 to recruit pol II to the promoters. We propose that only when GATA-1 attracts pol II to the locus control region can pol II access the promoter in a NF-E2-dependent manner.