Repression of aberrant splicing in human beta-globin pre-mRNA with HbE mutation by antisense oligoribonucleotide or splicing factor SF2/ASF.

Hemoglobin (Hb) E is the most common Hb variant among Southeast Asian populations. The mutation in codon 26 (GAG to AAG) of the beta-globin gene (beta E) induces alternative splicing, resulting in the production of normally and aberrantly spliced beta-globin mRNA. Compound heterozygosity for beta-thalassemia and HbE, beta-thalassemia/HbE disease, could lead to a severe thalassemia phenotype. Repression of aberrant splicing from the beta E mutation could ameliorate the severity in such patients. We showed that the aberrant splicing was partially repressed in cells treated with antisense oligoribonucleotide targeted to the aberrant 5' splice site. The maximum effect of the antisense oligoribonucleotide was observed at a concentration of 0.4 mumol/L, 36 hours after the treatment in our experiment. We also analyzed the effect of the transient and stable expression of SF2/ASF on aberrant splicing in cells expressing the beta E-globin gene. Partial repression of the aberrant splicing was also observed in both expression systems. Our results imply that antisense oligoribonucleotide treatment and SF2/ASF expression are possible therapeutic applications for beta-thalassemia/HbE disease.