Lin Qing, Chen Qi, Lin Lan, Zhou Jumin
The Wistar Institute, Philadelphia, Pennsylvania 19104, USA.
Genes Dev. 2004 Nov 1;18(21):2639-51. doi: 10.1101/gad.1230004.
Large gene complexes frequently use "specialized" DNA elements to ensure proper regulation of gene activities. The Promoter Targeting Sequence (PTS) from the Abdominal-B locus of the Drosophila Bithorax complex overcomes an insulator, and facilitates, yet restricts, distant enhancers to a single promoter. We found that this promoter-targeting activity is independent of an enhancer's tissue or temporal specificity, and can be remembered in all somatic cells in the absence of promoter activation. It requires an insulator for its establishment, but can be maintained by the PTS in the absence of an insulator. More importantly, the promoter-targeting activity can be remembered after the transgene is translocated to new chromosomal locations. These results suggest that promoter targeting is established independent of enhancer activity, and is maintained epigenetically throughout development and subsequent generations.
大型基因复合体经常利用“特殊”的DNA元件来确保基因活动的正确调控。果蝇双胸复合体腹部B位点的启动子靶向序列（PTS）可克服绝缘子的作用，并促进但限制远距离增强子作用于单个启动子。我们发现，这种启动子靶向活性与增强子的组织或时间特异性无关，并且在没有启动子激活的情况下，可在所有体细胞中被“记忆”。其建立需要绝缘子，但在没有绝缘子的情况下，PTS可维持这种活性。更重要的是，转基因易位到新的染色体位置后，启动子靶向活性仍可被“记忆”。这些结果表明，启动子靶向的建立独立于增强子活性，并且在整个发育过程及后代中通过表观遗传得以维持。
