miR-326 regulates HbF synthesis by targeting EKLF in human erythroid cells

Haploinsufficiency of erythroid Kriippel-like factor (EKLF/KLF1) has been shown recently to ameliorate the clinical severity of beta-thalassemia by increased expression levels of fetal hemoglobin (HbF). The underlying mechanisms for role of EKLF in regulating HbF are of great interest but remain incompletely understood. In this study, we used a combination of in silico, in vitro, and in vivo approaches to identify microRNAs (miRs) involved in EKLF regulation and to validate the role of miR-326 in HbF modification. We found that miR-326 suppresses EKLF expression directly by targeting its 3' untranslated region. miR-326 overexpression in K562 cells or CD34(+) hematopoietic progenitor cells resulted in reduced EKLF protein levels and was associated with elevated expression of gamma-globin, whereas inhibition of physiological miR-326 levels increased EKLF and thus reduced gamma-globin expression. Moreover, miR-326 expression is positively correlated with HbF levels in beta-thalassemia patients. Our results suggest that miR-326 plays a key role in regulating EKLF expression and in modifying the HbF level, which may provide a new strategy for activating HbF in individuals with beta-thalassemia or sickle cell disease. (C) 2018 Published by Elsevier Inc. on behalf of ISEH - Society for Hematology and Stem Cells.