Polycomb group (PcG) proteins are crucial chromatin regulators that maintain repression of lineage-inappropriate genes and are therefore required for stable cell fate. Recent advances show that PcG proteins form distinct multi-protein complexes in various cellular environments, such as in early development, adult tissue maintenance and cancer. This surprising compositional diversity provides the basis for mechanistic diversity. Understanding this complexity deepens and refines the principles of PcG complex recruitment, target-gene repression and inheritance of memory. We review how the core molecular mechanism of Polycomb complexes operates in diverse developmental settings and propose that context-dependent changes in composition and mechanism are essential for proper epigenetic regulation in development.

多梳组 (PcG) 蛋白是重要的染色质调节因子，可维持对谱系不当基因的抑制，因此是稳定细胞命运所必需的。最近的进展表明，PcG 蛋白在各种细胞环境中形成不同的多蛋白复合物，例如在早期发育、成人组织维持和癌症中。这种令人惊讶的组成多样性为机制多样性提供了基础。了解这种复杂性可以加深和完善 PcG 复合物募集、目标基因抑制和记忆遗传的原理。我们回顾了 Polycomb 复合物的核心分子机制如何在不同的发育环境中运作，并提出组成和机制的背景依赖性变化对于发育中适当的表观遗传调控至关重要。