The SET Oncoprotein Promotes Estrogen-Induced Transcription by Facilitating Establishment of Active Chromatin

SET is a multifunctional histone-binding oncoprotein that regulates transcription by an unclear mechanism. Here, we show that SET enhances estrogen-dependent transcription. SET knockdown abrogates transcription of estrogen-responsive genes and their enhancer RNAs (eRNAs). In response to 17β-estradiol (E2), SET binds to the estrogen receptor α (ERα) and is recruited to estrogen receptor α (ERα)-bound enhancers and promoters at estrogen response elements (EREs). SET functions as a histone H2 chaperone that dynamically associates with H2A.Z via its acidic C-terminal domain and promotes H2A.Z incorporation, ERα, MLL1 and KDM3A loading and modulates histone methylation at EREs. SET depletion diminishes recruitment of condensin complexes to EREs and impairs E2-dependent enhancer-promoter looping. Thus, SET boosts E2-induced gene expression by establishing an active chromatin structure at ERα-bound enhancers and promoters, which is essential for transcriptional activation. ChIP-seq of SET in MCF-7 cells. RNA-seq of MCF-7 control or estrogen treated cells with or without SET KD.