UC San Diego

FOXA1 is a DNA-binding protein that can regulate the estrogen transcriptional program. Although recent work has elucidated specific activities of the FOXA1 C-terminal domain, there is a dearth of information on the contribution of the N-terminal domain to FOXA1 function. By coupling FOXA1 shRNA knockdown with the expression of transgenic FOXA1 mutants, we show that the N-terminal domain is important for FOXA1’s ability to assist ER-α in activating estrogen-dependent transcription at promoters and enhancers. FOXA1 binding-site mutants showed that FOXA1-binding was critical for the recruitment of the transcription factor AP2-γ. The binding of AP2-γ was also affected by deletion of the FOXA1 N-terminal intrinsically-disordered domain. Knockdown and rescue experiments also showed that the FOXA1 N-terminus regulated H3K27 acetylation at estrogen-activated enhancers prior to ER-α recruitment without affecting the recruitment of FOXA1 or ER-α. Subsequently, proximity ligation mass spectrometry experiments suggested that FOXA1 was not only associated with a particular suite transcription factors, but also the Nuclear Remodeling and Deacetylase complex (NuRD). Estrogen-regulated enhancer FOXA1 binding-site deletion mutants were also shown to have decreased recruitment of the NuRD components CHD4 and HDAC2 compared to wild-type cells. Taken together, this data suggests that FOXA1 can regulate estrogen-dependent transcription through its N-terminus by recruiting AP2-γ and the NuRD complex.