Induction of endogenous gamma-globin gene expression with decoy oligonucleotide targeting Oct-1 transcription factor consensus sequence.

Human beta-globin disorders are relatively common genetic diseases cause by mutations in the beta-globin gene. Increasing the expression of the gamma-globin gene has great benefits in reducing complications associated with these diseases. The Oct-1 transcription factor is involved in the transcriptional regulation of the gamma-globin gene. The human gamma-globin genes (both Agamma and Ggamma-globin genes) carry three Oct-1 transcription factor consensus sequences within their promoter regions. We have studied the possibility of inducing gamma-globin gene expression using decoy oligonucleotides that target the Oct-1 transcription factor consensus sequence. A double-stranded 22 bp decoy oligonucleotide containing the Oct-1 consensus sequence was synthesized. The results obtained from our in vitro binding assay revealed a strong competitive binding of the decoy oligonucleotide for the Oct-1 transcription factor. When K562 human erythroleukemia cells were treated with the Oct-1 decoy oligonucleotide, significant increases in the level of the gamma-globin mRNA were observed. The results of our western blots further demonstrated significant increases of the fetal hemoglobin (HbF, alpha2gamma2) in the Oct-1 decoy oligonucleotide-treated K562 cells. The results of our immunoprecipitation (IP) studies revealed that the treatment of K562 cells with the Oct-1 decoy oligonucleotide significantly reduced the level of the endogenous gamma-globin gene promoter region DNA co-precipitated with the Oct-1 transcription factor. These results suggest that the decoy oligonucleotide designed for the Oct-1 transcription factor consensus sequence could induce expression of the endogenous gamma-globin gene through competitive binding of the Oct-1 transcription factor, resulting in activation of the gamma-globin genes. Therefore, disrupting the bindings of the Oct-1 transcriptional factors with the decoy oligonucleotide provides a novel approach for inducing expression of the gamma-globin genes. It also provides an innovative strategy for the treatment of many disease conditions, including sickle cell anemia and beta-thalassemia.