[Interaction of cis-regulatory element in the 5' flanking sequence of human beta-globin gene with trans-acting...

Human beta-globin gene mainly expressed in the adult bone marrow, while not expressed in fetal liver, adult liver and K562 cells. Using gel mobility shift assay, different protein factors binding to the regulatory elements (from -372 to -194 bp) in the 5' flanking sequence of human beta-globin gene were detected in the nuclear extracts from human fetal liver, adult liver and K562 cells respectively. Competitive experiments showed that both the protein factors from adult and K562 cells not only bind to negative control region 2 (NCR 2, from -372 to -224 bp), but also bind to positive control region (PCR, from -223 to -194 bp), suggesting that there may be similar mechanism to silence the expression of human beta-globin gene in these two kind of cells. The protein factor in human fetal liver only binds to NCR 2, indicating that there is a particular silencing mechanism for beta-globin gene expression in human fetal stage.