NRF2 mediates γ-globin gene regulation through epigenetic modifications in a β-YAC transgenic mouse model.

NRF2 is the master regulator for the cellular oxidative stress response and regulates gamma-globin gene expression in human erythroid progenitors and sickle cell disease mice. To explore NRF2 function, we established a human beta-globin locus yeast artificial chromosome transgenic/NRF2 knockout (beta-YAC/NRF2(-/-)) mouse model. NRF2 loss reduced gamma-globin gene expression during erythropoiesis and abolished the ability of dimethyl fumarate, an NRF2 activator, to enhance gamma-globin transcription. We observed decreased H3K4Me1 and H3K4Me3 chromatin marks and association of TATA-binding protein and RNA polymerase II at the beta-locus control region (LCR) and -gamma-globin gene promoters in beta-YAC/NRF2-/- mice. As a result, long-range chromatin interaction between the LCR DNase I hypersensitive sites and gamma-globin gene was decreased, while interaction with the beta-globin was not affected. Further, NRF2 loss silenced the expression of DNA methylcytosine dioxygenases TET1, TET2, and TET3 and inhibited gamma-globin gene DNA hydroxy-methylation. Subsequently, protein-protein interaction between NRF2 and TET3 was demonstrated. These data support the ability of NRF2 to mediate gamma-globin gene regulation through epigenetic DNA and histone modifications.