Hemoglobin subunit gamma 2 promoter -115 BCL11A repressor-binding motif (HBG2 -115 BCL11A motif)

The HBG2 promoter -115 BCL11A repressor-binding motif is a critical DNA regulatory element located 115 base pairs upstream of the transcription start site of the Hemoglobin Subunit Gamma 2 (HBG2) gene. This specific sequence, often characterized by a TGACCA motif, serves as a high-affinity binding site for the B-cell lymphoma/leukemia 11A (BCL11A) transcription factor, which is the primary repressor responsible for the fetal-to-adult hemoglobin switch after birth (Martyn et al., 2018, Nature Genetics). Naturally occurring mutations in this region, such as the British Hereditary Persistence of Fetal Hemoglobin (HPFH) mutation, disrupt BCL11A binding and lead to elevated fetal hemoglobin (HbF) levels throughout adulthood. In therapeutic contexts for sickle cell disease and beta-thalassemia, this motif is targeted by gene-editing technologies to lift the repression of HbF (Liu et al., 2018, Cell). By preventing BCL11A from binding to this site, cells can resume production of HbF, which functionally substitutes for defective adult hemoglobin and reduces clinical symptoms. Investigational therapies like BEAM-101 and EDIT-301 specifically utilize base editing or CRISPR-mediated disruption of this promoter region to achieve therapeutic HbF induction (Beam Therapeutics, 2024; Editas Medicine, 2024).

Other names

HBG2 promoter BCL11A binding site-115 site of HBG2 promoterFetal hemoglobin repressor binding siteHBG2 -115 TGACCA motifGamma-globin promoter BCL11A motif

Disruption of the BCL11A binding motif via gene editing (such as CRISPR/Cas12a or base editing) to prevent transcriptional repression and induce fetal hemoglobin (HbF) synthesis (Martyn et al., 2018, Nature Genetics).