Transcription factors activate genes through the phase separation capacity of their activation domains [ChIP-seq]

Gene expression is controlled by transcription factors (TFs) that consist of DNA-binding domains (DBDs) and activation domains (ADs). The DBDs have been well- characterized, but little is known about the mechanisms by which ADs effect gene activation. Here we report that diverse ADs form phase-separated condensates with the Mediator coactivator. For the OCT4 and GCN4 TFs, we show that the ability to form phase-separated droplets with Mediator in vitro and the ability to activate genes in vivo are dependent on the same amino acid residues. For the estrogen receptor (ER), a ligand-dependent activator, we show that estrogen enhances phase separation with Mediator, again linking phase separation with gene activation. These results suggest that diverse TFs can interact with Mediator through the phase-separating capacity of their ADs and that formation of condensates with Mediator is involved in gene activation. ChIP-Seq against OCT4 and MED1 in mouse embryonic stem cells after OCT4 degradation

基因表达由转录因子（Transcription Factors, TFs）调控，这类因子包含DNA结合结构域（DNA-binding Domains, DBDs）与激活结构域（Activation Domains, ADs）。DNA结合结构域已得到充分研究与表征，但人们对激活结构域介导基因激活的具体机制仍知之甚少。本研究发现，多种激活结构域可与中介体辅激活因子（Mediator coactivator）形成相分离凝聚体。针对OCT4与GCN4两种转录因子，本研究证实，其在体外与中介体形成相分离液滴的能力，以及在体内激活基因的能力，均依赖于同一组氨基酸残基。对于配体依赖性激活因子雌激素受体（Estrogen Receptor, ER），本研究证实雌激素可增强其与中介体的相分离能力，再次将相分离过程与基因激活功能关联起来。上述结果表明，多种转录因子可通过其激活结构域的相分离能力与中介体发生相互作用，且与中介体形成凝聚体的过程参与了基因激活的调控。本研究包含OCT4降解后的小鼠胚胎干细胞中针对OCT4与MED1的染色质免疫沉淀测序（ChIP-Seq）数据集。