Transient Expression Assay of Aγ-588 (A/G) Mutations in the K562 Cell Line

Background: In the previous study, we have shown that the presence of A allele at position -588 in Aγ-globin gene was highly frequent and closely associated with fetal hemoglobin elevation among β-thalassemia intermedia patients. Therefore, we decided to investigate whether this allele (A allele at -588) could result in an increase in Aγ-globin gene expression to ameliorate the severity of the disease in thalassemia patients. Methods: Three constructs containing µ locus control region, Aγ-globin and β-globin genes were designed and employed in the transient expression assay. The difference among constructs was in the promoter region of Aγ-globin gene (A and G alleles at -588). A construct with T to C base substitution at -175 of Aγ-globin, created by site-directed mutagenesis, was selected as positive control. The K562 cell line was transfected with the above constructs. Subsequently, the expression of Aγ-globin gene was determined by quantitative real-time reverse transcription-PCR. Results: There was not a significant increase in the expression of Aγ-globin gene in the construct containing A allele comparing the one with G allele at -588. Conclusions: -588 (A>G) mutation does not play a major role in regulation of Aγ-globin gene, suggesting that other factors may be involved.