Giner-Laguarda Natalia, Vidal Miguel
Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas, Ramiro de Maeztu 9, 28040 Madrid, Spain.
Epigenomes. 2020 Aug 17;4(3):17. doi: 10.3390/epigenomes4030017.
Chromatin regulators of the Polycomb group of genes are well-known by their activities as transcriptional repressors. Characteristically, their presence at genomic sites occurs with specific histone modifications and sometimes high-order chromatin structures correlated with silencing of genes involved in cell differentiation. However, evidence gathered in recent years, on flies and mammals, shows that in addition to these sites, Polycomb products bind to a large number of active regulatory regions. Occupied sites include promoters and also intergenic regions, containing enhancers and super-enhancers. Contrasting with occupancies at repressed targets, characteristic histone modifications are low or undetectable. Functions on active targets are dual, restraining gene expression at some targets while promoting activity at others. Our aim here is to summarize the evidence available and discuss the convenience of broadening the scope of research to include Polycomb functions on active targets.
多梳基因家族的染色质调控因子以其作为转录抑制因子的活性而闻名。其特点是，它们在基因组位点的存在伴随着特定的组蛋白修饰，有时还伴随着与细胞分化相关基因沉默相关的高阶染色质结构。然而，近年来在果蝇和哺乳动物中收集的证据表明，除了这些位点外，多梳产物还与大量活跃的调控区域结合。占据的位点包括启动子以及基因间区域，其中包含增强子和超级增强子。与在抑制靶点上的占据情况形成对比的是，特征性的组蛋白修饰水平较低或无法检测到。在活跃靶点上的功能是双重的，在一些靶点上抑制基因表达，而在另一些靶点上促进活性。我们在此的目的是总结现有的证据，并讨论扩大研究范围以纳入多梳在活跃靶点上的功能的便利性。
