Kruppel-like factor 1-GATA1 fusion protein improves the sickle cell disease phenotype in mice both in vitro and in vivo

Sickle cell disease (SCD) and ss-thalassemia are among the most common genetic disorders worldwide, affecting global health and mortality. Hemoglobin A2 (HbA2, alpha 2d2) is expressed at a low level in adult blood due to the lack of the Kruppel-like factor 1 (KLF1) bindingmotif in the delta-globin promoter region. However, HbA2 is fully functional as an oxygen transporter, and could be a valid antisickling agent in SCD, as well as a substitute for hemoglobin A in ss-thalassemia. We have previously demonstrated that KLF1-GATA1 fusion protein could interact with the delta-globin promoter and increase delta-globin expression in human primary CD34(+) cells. We report the effects of 2 KLF1-GATA1 fusion proteins on hemoglobin expression, as well as SCD phenotypic correction in vitro and in vivo. Forced expression of KLF1-GATA1 fusion protein enhanced delta-globin gene and HbA2 expression, as well as reduced hypoxia-related sickling, in erythroid cells cultured from both human sickle CD34(+) cells and SCD mouse hematopoietic stem cells (HSCs). The fusion proteins had no impact on erythroid cell differentiation, proliferation, and enucleation. Transplantation of highly purified SCDmouseHSCs expressing KLF1-GATA1 fusion protein into SCD mice lessened the severity of the anemia, reduced the sickling of red blood cells, improved SCD-related pathological alterations in spleen, kidney, and liver, and restored urine-concentrating ability in recipientmice. Taken together, these results indicate that the use of KLF1-GATA1 fusion constructs may represent a new gene therapy approach for hemoglobinopathies.

Automated summary

This study investigated the role of KLF1-GATA1 fusion proteins in hemoglobin expression and phenotypic correction of SCD. The results showed that KLF1-GATA1 fusion proteins enhanced the expression of δ-globin and HbA2, reducing hypoxia-related sickling in erythroid cells. Furthermore, transplantation of SCD mouse hematopoietic stem cells expressing KLF1-GATA1 fusion proteins improved anemia severity, reduced sickling of red blood cells, and restored organ function in SCD mice, suggesting the potential of KLF1-GATA1 fusion constructs as a new gene therapy approach for hemoglobinopathies.