The beta globin 3' enhancer element confers regulated expression on the human gamma globin gene in the human embryonic-fetal erythroleukemia cell line K562.

We have constructed fusion genes comprised of gamma and beta globin elements and globin sequences linked to neomycin resistance (neoR) genes to define the cis acting sequences responsible for developmental stage-specific expression and induction of fetal globin genes in embryonic-fetal erythroleukemia K562 cells. The results indicate that the gamma promoter is required for proper initiation of transcription. However, the accumulation of gamma globin transcripts in response to hemin induction requires the additional presence of either gamma intervening sequence 2 or the 3' enhancer element of the beta globin gene. Thus, the gamma promoter may provide the elements for developmental stage-specific gene expression during fetal life. By contrast, the beta 3' enhancer is erythroid-specific but not developmental stage- or gene-specific.