Cooperative activities of hematopoietic regulators recruit RNA polymerase II to a tissue-specific chromatin domain

The hematopoietic transcription factor GATA-1 regulates erythropoiesis and beta-globin expression. Although consensus GATA-1 binding sites exist throughout the murine beta-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 11 (pol 11) recruitment to subregions of the locus control region and to the beta-globin promoters. The hematopoietic factor NF-E2 cooperated with GATA-1 to recruit pol 11 to the promoters. We propose that only when GATA-1 attracts pol 11 to the locus control region can pol 11 access the promoter in a NF-E2-dependent manner.