DIFFERENTIAL BINDING OF THE NFE3 AND CP1 NFY TRANSCRIPTION FACTORS TOTHE HUMAN GAMMA-GLOBIN AND EPSILON-GLOBIN CCAAT BOXES/

Naturally occurring nondeletional mutations affecting the distal CCAAT box of the human gamma-globin gene promoter result in hereditary pers istence of fetal hemoglobin in adult life. Although the distal CCAAT b ox is the target of several factors, including CP1/NFY, CDP, GATA-1 an d NFE3, only NFE3 binding activity is consistently sensitive to well c haracterized mutations in this region such as G(-117) --> A, C-114 --> T, and Delta 13 hereditary persistence of fetal hemoglobin. We extens ively characterized the binding specificities of NFE3 and demonstrated that NFE3 has unique properties with respect to other CCAAT box-bindi ng proteins. Affinity-purified NFE3 from erythroid K562 cells binds th e distal but not the proximal human gamma-globin CCAAT box, the single CCAAT box of the human epsilon-globin promoter, and the proximal CCAA T box of the evolutionarily related Galago crassicaudatus gamma-globin gene. Within the epsilon-globin CCAAT box, NFE3 represents the major and almost exclusive binding activity. Disruption of such a binding si te essentially inactivates the epsilon-globin promoter, suggesting tha t NFE3 plays an important role in the embryonic expression of this gen e.