Comprehensive Genomic Analysis Reveals that the Pioneering Function of FOXA1 Is Independent of Hormonal Signaling

oleh: Silvia-E. Glont, Igor Chernukhin, Jason S. Carroll

Format: Article
Diterbitkan: Elsevier 2019-03-01

Deskripsi

Summary: Considerable work has linked hormone receptors, such as estrogen receptor-alpha (ER), with the pioneer factor FOXA1. Altered FOXA1 levels contribute to endocrine-resistant breast cancer, where it maintains ER-chromatin interactions, even in contexts in which cells are refractory to ER-targeted drugs. A recent study controversially suggests that FOXA1 binding can be induced by hormonal pathways, including the estrogen-ER complex. We now show that the vast majority (>99%) of FOXA1 binding events are unaffected by steroid activation. A small number (<1%) of FOXA1 binding sites appear to be induced by estrogen, but these are created from chromatin interactions between ER binding sites and adjacent FOXA1 binding sites and do not represent genuine new FOXA1-pioneering elements. FOXA1 is therefore not regulated by estrogen and remains a bone fide pioneer factor that is entirely upstream of the ER complex. : Glont et al. show that FOXA1 binding sites are not regulated by hormones. A small number (<1%) of FOXA1 binding events appear to be estrogen regulated, but these are shadow peaks that are created via pre-existing binding sites that form chromatin loops.