Grummt Ingrid
Chromosoma. 2013 Dec;122(6):487-97. doi: 10.1007/s00412-013-0430-0.
All organisms sense and respond to conditions that stress their homeostasis by downregulating the synthesis of rRNA and ribosome biogenesis, thus designating the nucleolus as the central hub in coordinating the cellular stress response. One of the most intriguing roles of the nucleolus, long regarded as a mere ribosome-producing factory, is its participation in monitoring cellular stress signals and transmitting them to the RNA polymerase I (Pol I) transcription machinery. As rRNA synthesis is a most energy-consuming process, switching off transcription of rRNA genes is an effective way of saving the energy required to maintain cellular homeostasis during acute stress. The Pol I transcription machinery is the key convergence point that collects and integrates a vast array of information from cellular signaling cascades to regulate ribosome production which, in turn, guides cell growth and proliferation. This review focuses on the mechanisms that link cell physiology to rDNA silencing, a prerequisite for nucleolar integrity and cell survival.
所有生物体都会感知并响应那些破坏其体内平衡的条件，方式是下调rRNA的合成和核糖体生物发生，因此将核仁指定为协调细胞应激反应的中心枢纽。长期以来，核仁一直被视为单纯的核糖体生产工厂，其最引人入胜的作用之一是参与监测细胞应激信号并将其传递给RNA聚合酶I（Pol I）转录机制。由于rRNA合成是一个极其耗能的过程，在急性应激期间关闭rRNA基因的转录是节省维持细胞体内平衡所需能量的有效方式。Pol I转录机制是关键的汇聚点，它收集并整合来自细胞信号级联的大量信息，以调节核糖体的产生，而核糖体的产生又指导细胞生长和增殖。本综述重点关注将细胞生理学与rDNA沉默联系起来的机制，rDNA沉默是核仁完整性和细胞存活的先决条件。
