Department of Cell Biology, Erasmus MC, Wytemaweg 80, 3015 CN, Rotterdam, Netherlands.
Center for Proteomics, Erasmus MC, 3015 CN, Rotterdam, Netherlands.
Nat Commun. 2019 Jun 17;10(1):2669. doi: 10.1038/s41467-019-10502-8.
The Mediator complex regulates transcription by connecting enhancers to promoters. High Mediator binding density defines super enhancers, which regulate cell-identity genes and oncogenes. Protein interactions of Mediator may explain its role in these processes but have not been identified comprehensively. Here, we purify Mediator from neural stem cells (NSCs) and identify 75 protein-protein interaction partners. We identify super enhancers in NSCs and show that Mediator-interacting chromatin modifiers colocalize with Mediator at enhancers and super enhancers. Transcription factor families with high affinity for Mediator dominate enhancers and super enhancers and can explain genome-wide Mediator localization. We identify E-box transcription factor Tcf4 as a key regulator of NSCs. Tcf4 interacts with Mediator, colocalizes with Mediator at super enhancers and regulates neurogenic transcription factor genes with super enhancers and broad H3K4me3 domains. Our data suggest that high binding-affinity for Mediator is an important organizing feature in the transcriptional network that determines NSC identity.
中介复合物通过将增强子连接到启动子来调节转录。高中介结合密度定义了超级增强子，它们调节细胞身份基因和癌基因。中介的蛋白质相互作用可能解释了其在这些过程中的作用，但尚未全面确定。在这里，我们从神经干细胞 (NSC) 中纯化了中介，并鉴定了 75 种蛋白质-蛋白质相互作用伙伴。我们在 NSC 中鉴定了超级增强子，并表明与中介相互作用的染色质修饰因子与增强子和超级增强子上的中介共定位。对 Mediator 具有高亲和力的转录因子家族主导着增强子和超级增强子，并且可以解释全基因组 Mediator 定位。我们确定 E 盒转录因子 Tcf4 是 NSC 的关键调节因子。Tcf4 与 Mediator 相互作用，与 Mediator 在超级增强子上共定位，并调节具有超级增强子和广泛 H3K4me3 结构域的神经发生转录因子基因。我们的数据表明，对 Mediator 的高结合亲和力是决定 NSC 身份的转录网络中的一个重要组织特征。
