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Restoration of correct splicing of βIVS2-654-globin pre-mRNA was previously accomplished in erythroid cells from β-thalassemia/HbE patients by an engineered U7 small nuclear RNA (snRNA) that carried a sequence targeted to the cryptic branch point and an exonic splicing enhancer, U7.BP+623 snRNA. In this study, this approach was tested in thalassemic mice carrying the βIVS2-654 mutation. While correction of βIVS2-654 pre-mRNA splicing was achieved in erythroid progenitors transduced with a lentiviral vector carrying the U7.BP+623 snRNA, a high level of truncated U7.BP+623 snRNA was also observed. The discrepancy of processing of the modified U7 snRNA in human and mouse constructs hamper the evaluation of pathologic improvement in mouse model. [ABSTRACT FROM AUTHOR]

Induction of fetal hemoglobin (HbF) ameliorates the clinical severity of β-thalassemias. Histone methyltransferase LSD1 enzyme removes methyl groups from the activating chromatin mark histone 3 lysine 4 at silenced genes, including the γ-globin genes. LSD1 inhibitor RN-1 induces HbF levels in cultured human erythroid cells. Here, the HbF-inducing activity of RN-1 was investigated in erythroid progenitor cells derived from β 0 -thalassemia/ hemoglobin E (HbE) patients. The significant and reproducible increases in γ-globin transcript and HbF expression upon RN-1 treatment were demonstrated in erythroid cells with divergent HbF baseline levels, the average of HbF induction was 17.7±0.8%. RN-1 at low concentration did not affect viability and proliferation of erythroid cells, but decreases in cell number were observed in cells treated with RN-1 at high concentration. Delayed terminal erythroid differentiation was revealed in β 0 -thalassemia/HbE erythroid cells treated with RN-1 as similar to other compounds that target LSD1 activity. Downregulation of repressors of γ- globin expression; NCOR1 and SOX6, was observed in RN-1 treatment. These findings provide proof of the concept that LSD1 epigenetic enzyme is a potential therapeutic target for β 0 -thalassemia/HbE patients., Competing Interests: Conflict of interest: The authors declare no potential conflict of interest., (©Copyright: the Author(s).)