Valenzuela Lourdes, Kamakaka Rohinton T
Unit on Chromatin and Transcription, NICHD/NIH, Bethesda, Maryland 20892, USA.
Annu Rev Genet. 2006;40:107-38. doi: 10.1146/annurev.genet.39.073003.113546.
Active and silenced chromatin domains are often in close juxtaposition to one another, and enhancer and silencer elements operate over large distances to regulate the genes in these domains. The lack of promiscuity in the function of these elements suggests that active mechanisms exist to restrict their activity. Insulators are DNA elements that restrict the effects of long-range regulatory elements. Studies on different insulators from different organisms have identified common themes in their mode of action. Numerous insulators map to promoters of genes or have binding sites for transcription factors and like active chromatin hubs and silenced loci, insulators also cluster in the nucleus. These results bring into focus potential conserved mechanisms by which these elements might function in the nucleus.
活跃染色质结构域和沉默染色质结构域常常彼此紧密相邻，增强子元件和沉默子元件在远距离发挥作用以调控这些结构域中的基因。这些元件功能上缺乏随意性表明存在限制其活性的活跃机制。绝缘子是限制远距离调控元件作用的DNA元件。对来自不同生物体的不同绝缘子的研究已经确定了它们作用模式中的共同主题。许多绝缘子定位于基因启动子处或具有转录因子结合位点，并且如同活跃染色质中心和沉默基因座一样，绝缘子也在细胞核中聚集。这些结果使这些元件可能在细胞核中发挥作用的潜在保守机制成为焦点。
