Unravelling the chromatin landscape and enhancer logic mediating spatiotemporal patterning of early cardiovascular progenitors [ChIP-seq]. Unravelling the chromatin landscape and enhancer logic mediating spatiotemporal patterning of early cardiovascular progenitors [ChIP-seq]

The mammalian heart arises from various populations of Mesp1-expressing cardiovascular progenitors (CPs) that are specified during the early stages of gastrulation. Mesp1 acts as a master regulator of CP specification and differentiation. However, how Mesp1 regulates the chromatin landscape of nascent mesodermal cells to define the temporal and spatial patterning of the distinct populations of CP remains unknown. Here, by combining ChIP-seq, RNA-seq and ATAC-seq during mouse pluripotent stem cell differentiation, we defined the temporal remodelling of the chromatin landscape mediated by Mesp1. We identified different enhancers that are temporally regulated to erase the pluripotent state and specify the pools of CPs that mediate heart development. We found that Mesp1 acts as a pioneer transcription factor (TF) and identified Zic TFs as essential cofactors that regulate Mesp1 pioneer activity at key mesodermal enhancers, thereby regulating the chromatin remodelling and gene expression associated with the specification of the different populations of CPs in vivo. Our study identifies the dynamics of the chromatin landscape and enhancer remodelling associated with temporal patterning of early mesodermal cells into the distinct populations of CPs that mediate heart development. Overall design: ChIP-seq samples targeting 3HA-tagged Mesp1, 3-HA tagged Zic3 and H3K27Ac

哺乳动物心脏起源于多个表达Mesp1的心血管祖细胞（cardiovascular progenitors, CPs）群体，这些祖细胞在原肠运动早期阶段得以特化。Mesp1是心血管祖细胞特化与分化的核心调控因子。然而，Mesp1如何调控新生中胚层细胞的染色质景观，以界定不同心血管祖细胞群体的时空模式，这一问题迄今尚未明确。在此，我们通过在小鼠多能干细胞分化过程中联合应用ChIP-seq、RNA-seq及ATAC-seq技术，系统解析了Mesp1介导的染色质景观的时序重塑过程。我们鉴定出一批受时序调控的增强子，它们可介导多能状态的消退，并特化出介导心脏发育的心血管祖细胞库。我们发现，Mesp1作为先锋转录因子（transcription factor, TF）发挥功能，并鉴定出Zic转录因子作为关键辅因子，可调控Mesp1在关键中胚层增强子处的先锋活性，进而调控体内不同心血管祖细胞群体特化相关的染色质重塑与基因表达程序。本研究阐明了早期中胚层细胞时序模式化为不同心血管祖细胞群体以介导心脏发育过程中，染色质景观与增强子重塑的动态变化。整体实验设计：靶向3HA标记的Mesp1、3-HA标记的Zic3以及H3K27Ac的ChIP-seq样本。