Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada.
Center for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto M5S 1A8, Canada.
Cell Rep. 2013 Dec 26;5(6):1611-24. doi: 10.1016/j.celrep.2013.11.021. Epub 2013 Dec 12.
A small toolkit of morphogens is used repeatedly to direct development, raising the question of how context dictates interpretation of the same cue. One example is the transforming growth factor β (TGF-β) pathway that in human embryonic stem cells fulfills two opposite functions: pluripotency maintenance and mesendoderm (ME) specification. Using proteomics coupled to analysis of genome occupancy, we uncover a regulatory complex composed of transcriptional effectors of the Hippo pathway (TAZ/YAP/TEAD), the TGF-β pathway (SMAD2/3), and the pluripotency regulator OCT4 (TSO). TSO collaborates with NuRD repressor complexes to buffer pluripotency gene expression while suppressing ME genes. Importantly, the SMAD DNA binding partner FOXH1, a major specifier of ME, is found near TSO elements, and upon fate specification we show that TSO is disrupted with subsequent SMAD-FOXH1 induction of ME. These studies define switch-enhancer elements and provide a framework to understand how cellular context dictates interpretation of the same morphogen signal in development.
一小套形态发生素被反复用于指导发育,这就提出了一个问题,即上下文如何决定对相同线索的解释。一个例子是转化生长因子 β(TGF-β)途径,在人类胚胎干细胞中,它发挥着两种相反的功能:多能性维持和中胚层(ME)特化。我们使用蛋白质组学结合基因组占据分析,揭示了一个由 Hippo 途径(TAZ/YAP/TEAD)、TGF-β 途径(SMAD2/3)和多能性调节剂 OCT4(TSO)的转录效应物组成的调节复合物。TSO 与 NuRD 抑制复合物合作,缓冲多能性基因表达,同时抑制 ME 基因。重要的是,SMAD 的 DNA 结合伙伴 FOXH1,ME 的主要决定因素,被发现靠近 TSO 元件,并且在命运特化后,我们表明 TSO 被破坏,随后 SMAD-FOXH1 诱导 ME。这些研究定义了开关增强子元件,并为理解细胞上下文如何决定对发育中相同形态发生素信号的解释提供了框架。