Activation of ?-globin gene expression by GATA1 and NF-Y in hereditary persistence of fetal hemoglobin

Naturally occurring mutations in the γ-globin promoters can result in hereditary persistence of fetal hemoglobin (HPFH), a benign condition that ameliorates the severity of β-hemoglobinopathies through increased post-natal fetal hemoglobin (HbF) expression. Mutations in the γ-globin promoters result in loss or de novo recruitment of transcription factors, yet the cis­-regulatory elements involved in γ-globin transcription in the context of HPFH are not clearly defined. We demonstrate that the -115 cluster of HPFH mutations require GATA1 binding to at -186 in cooperation with NF-Y at the proximal CCAAT box at -85 for γ-globin expression. We show that multiple HPFH mutations increase HbF in an erythroid cell line and result in GATA1 binding at -186. Mutation of the -186 GATA motif in HPFH erythroid cell lines and erythroid-differentiated CD34+ cells resulted in loss of GATA1 binding and reduction in fetal hemoglobin. NF-Y ChIP-seq in HPFH erythroid cell lines demonstrated binding to the proximal CCAAT box at -85 was also found to be critical for HPFH-mediated γ-globin expression. Together, the -186 GATA motif and -85 proximal CCAAT box function in an additive and independent manner. Our results reveal detailed evidence for common, positive acting cis-regulatory elements that may provide more general mechanisms for erythroid gene expression. Overall design: ChIP-seq experiments were performed in HUDEP-2 cells harboring mutations in the ?-globin promoter for GATA1 and NF-YB. Input samples were used as control ATAC-seq experiments were performed in undifferentiated HUDEP-2 cells harboring mutations in the -115 CCAAT box of the ?-globin promoter. Hi-C experiments were performed in WT and single HBG allele HUDEP-2 cells