Polycomb group proteins (PcGs) control the epigenetic and transcriptional state of developmental genes and regulatory elements during mammalian embryogenesis. Moreover, PcGs can also contribute to 3D genome organization, adding an additional layer of complexity to their regulatory functions. Understanding the mechanistic basis and the dynamics of PcG-dependent chromatin structures will help us untangle the full complexity of PcG function during development. Since most studies concerning the 3D organization of PcG-bound chromatin in mammals have been performed in embryonic stem cells (ESCs), here we will focus on this cell type characterized by its unique self-renewal and pluripotency properties. More specifically, we will highlight recent findings and discuss open questions regarding how PcG-dependent changes in 3D chromatin architecture control gene expression, cellular identity and differentiation potential in ESCs. We believe that this can serve to illustrate the diverse regulatory mechanisms by which PcG proteins control the proper execution of gene expression programs during mammalian embryogenesis.

中文翻译：

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polycomb蛋白是胚胎干细胞中3D基因组结构的组织者。

polycomb组蛋白（PcGs）控制哺乳动物胚胎发生过程中发育基因和调节元件的表观遗传和转录状态。此外，PcG还可以促进3D基因组的组织，为其调节功能增加一层额外的复杂性。了解PcG依赖的染色质结构的力学基础和动力学将有助于我们在开发过程中解开PcG功能的全部复杂性。由于有关哺乳动物中与PcG结合的染色质的3D组织的大多数研究都是在胚胎干细胞（ESC）中进行的，因此在这里，我们将专注于以其独特的自我更新和多能性特征为特征的这种细胞类型。进一步来说，我们将重点介绍最近的发现并讨论有关3D染色质结构中PcG依赖性变化如何控制ESC中基因表达，细胞身份和分化潜能的开放性问题。我们认为，这可以用来说明PcG蛋白控制哺乳动物胚胎发生过程中基因表达程序的正确执行的各种调节机制。