Martinez Anne-Marie, Cavalli Giacomo
Institute of Human Genetics, CNRS, Montpellier, France.
Cell Cycle. 2006 Jun;5(11):1189-97. doi: 10.4161/cc.5.11.2781. Epub 2006 Jun 1.
Polycomb group (PcG) and trithorax group (trxG) proteins are evolutionarily conserved chromatin modifiers that have well known roles in the maintenance of silent and active expression states of homeotic genes. PcG proteins may also be involved in the control of cellular proliferation, as several PcG complexes have been shown to act either as proto-oncogenes or as tumor suppressors in vertebrates. In Drosophila, PcG factors associate with specific DNA regions termed PcG response elements (PREs), and a PRE was recently identified in the gene encoding Cyclin A. Still, it is not yet clear how PcG complexes could control cell cycle progression. Beyond acting as stable silencers of cell cycle genes during the differentiation process, PcG complexes might also be integrators and/or modulators of cell cycle checkpoints in dividing cells. Here, we discuss this dual aspect of PcG involvement in epigenetic cell cycle control.
多梳蛋白家族（PcG）和三胸节蛋白家族（trxG）是进化上保守的染色质修饰因子，在维持同源异型基因的沉默和活跃表达状态方面具有众所周知的作用。PcG蛋白也可能参与细胞增殖的调控，因为在脊椎动物中，几种PcG复合物已被证明可作为原癌基因或肿瘤抑制因子发挥作用。在果蝇中，PcG因子与称为PcG反应元件（PREs）的特定DNA区域相关联，最近在编码细胞周期蛋白A的基因中鉴定出了一个PRE。然而，PcG复合物如何控制细胞周期进程尚不清楚。除了在分化过程中作为细胞周期基因的稳定沉默因子发挥作用外，PcG复合物还可能是分裂细胞中细胞周期检查点的整合者和/或调节者。在此，我们讨论PcG参与表观遗传细胞周期调控的这两个方面。
