siRNA-mediated reduction of α-globin results in phenotypic improvements in β-thalassemic cells

Abstract

β-thalassemia is an inherited hemoglobinopathy caused by defective synthesis of the β-globin chain of hemoglobin, leading to imbalanced globin chain synthesis. Excess α-globin precipitates in erythroid progenitor cells resulting in cell death, ineffective erythropoiesis and severe anemia. Decreased α-globin synthesis leads to milder symptoms, exemplified in individuals who co-inherit α- and β-thalassemia. In this study, we investigated the feasibility of utilizing short-interfering RNA (siRNA) to mediate reductions in α-globin expression. A number of siRNA sequences targeting murine α-globin were tested in hemoglobinized murine erythroleukemic cells. One highly effective siRNA sequence (si-α 4) was identified and reduced α-globin by approximately 65% at both the RNA and the protein level. Electroporation of si-α 4 into murine thalassemic primary erythroid cultures restored α :β-globin ratios to balanced wild-type levels and resulted in detectable phenotypic correction. These results indicate that siRNA-mediated reduction of α-globin has potential therapeutic applications in the treatment of β-thalassemia.