Transcriptional Factor SOX2, LncRNA HBL1, microRNA1 and PRC2 Epigenetic Complex Compose a Network to Orchestrate Cardiac Differentiation from Human Pluripotent Stem Cells

项目总结/摘要 在过去的几十年里，心脏发育的研究主要集中在保守基因上， 调节机制，它控制多个物种的心脏发生的各个方面， 从果蝇到老鼠这些保守的基因程序包括心脏转录因子（如Nkx2.5， Isl 1，Tbx 20），microRNA和表观遗传调节因子。尽管在进化过程中 在心脏发生中，人类心脏表现出独特的特性，包括独特的形态发生和 电生理特性这些物种特异性差异表明存在新的遗传学差异。 每个物种的程序。由于实验条件的限制，目前尚不清楚其作用机制， 调节人类心脏发生的独特方面，以及人类特异性机制如何与 保守的基因程序来微调人类心脏发育。最近，越来越多的证据 证明了长链非编码RNA（lncRNA）在细胞命运规范中起重要作用， 器官形成包括心脏lncRNA是大于200 bp的非编码转录物，其占 >40%的人类转录组。许多lncRNA是组织特异性和物种特异性的。最近，我们发现 一种新的人类特异性lncRNA，命名为HeartBrake LncRNA 1（HBL 1）（Dev. Cell. 2017，4：333-8）。HBL 1是 在人诱导多能干细胞（hiPSC）的细胞质和细胞核中高度表达。细胞溶质 HBL 1通过抵消microRNA 1（MIR 1）调节hiPSC的心肌细胞（CM）发育。 多能性标记基因SOX 2激活HBL 1转录。在这个建议中，我们将进一步分析，一部小说， 核HBL 1通过与polycomb相互作用启动心脏基因表达程序的机制 阻遏复合物2（PRC 2）。此外，我们将测试一个假设，即HBL 1增加了一个新的人类- 在保守的心源性轴之上的特定调节机制。总的来说，中心假设是 转录因子SOX 2、lncRNA HBL 1、microRNA-1和PRC 2复合物组成了一个完整网络， 从多能干细胞中控制人类心脏发生。

PROJECT SUMMARY/ABSTRACT During the past decades, studies of heart development have been mainly focused on conserved gene regulatory mechanisms, which control various aspects of cardiogenesis across multiple species from drosophila to mouse. These conserved gene programs include cardiac transcriptional factors (such as Nkx2.5, Isl1, Tbx20), microRNAs, and epigenetic regulators. Despite the high evolutionary conservation of cardiogenesis, the human heart exhibits unique properties, including distinctive morphogenesis and electrophysiological properties. These species-specific differences suggest the existence of novel genetic programs in each species. As the limitation of experimental setting, it remains unclear the mechanisms that regulate unique aspects of human cardiogenesis, and how human-specific mechanisms interact with conserved gene programs to fine-tune human heart development. Recently, accumulating evidence demonstrated that long noncoding RNAs (lncRNAs) play important roles in cell fate specification and organogenesis, including the heart. LncRNAs are greater than 200bp non-coding transcripts, which account for >40% of human transcriptome. Many lncRNAs are tissue-specific and species-specific. Recently, we identified a novel human-specific lncRNA, named Heart Brake LncRNA1 (HBL1) (Dev. Cell. 2017, 4:333-8). HBL1 is highly expressed in both cytoplasm and nucleus of human induced pluripotent stem cells (hiPSCs). Cytosolic HBL1 modulates cardiomyocyte (CM) development from hiPSCs by counteracting microRNA1 (MIR1). Pluripotency marker gene SOX2 activates HBL1 transcription. In this proposal, we will analyze further, a novel mechanism of nuclear HBL1 in initiating the cardiac gene-expressing program via interacting with polycomb repressive complex 2 (PRC2). Additionally, we will test a hypothesis that HBL1 adds a new layer of human- specific regulatory mechanism on top of a conserved cardiogenic axis. All together, the central hypothesis is that transcriptional factor SOX2, lncRNA HBL1, microRNA-1 and PRC2 complex composite a whole network to control human cardiogenesis from pluripotent stem cells.