FUNCTIONAL ERYTHROID PROMOTERS CREATED BY INTERACTION OF THE TRANSCRIPTION FACTOR GATA-1 WITH CACCC AND AP-1/NFE-2 ELEMENTS

We have investigated interactions between the erythroid transcription factor GATA-1 and factors binding two cis-acting elements commonly linked to GATA sites in erythroid control elements. GATA-1 is present at all stages of erythroid differentiation, is necessary for erythropoiesis, and binds sites in all erythroid control elements. However, minimal promoters containing GATA-1 sites are inactive when tested in erythroid cells. Based on this observation, two erythroid cis elements, here termed CACCC and AP-1/NFE-2, were linked to GATA sites in minimal promoters. None of the elements linked only to a TATA box created an active promoter, but GATA sites linked to either CACCC or AP-1/NFE-2 elements formed strong erythroid promoters. A mutation of T to C at position -175 in the gamma-globin promoter GATA site, associated with hereditary persistence of fetal hemoglobin (HPFH), increased expression of these promoters in both fetal and adult cells. A construct bearing the beta-globin CACCC element was more active in adult and less active in fetal erythroid cells, when compared with the gamma-globin CACCC element. These studies suggest that erythroid control elements are formed by the interactions of at least three transcription factors, none of which functions alone.