Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA.
Department of Oncological Sciences, University of Utah, Salt Lake City, UT, USA.
Nucleic Acids Res. 2020 Jul 9;48(12):6597-6610. doi: 10.1093/nar/gkaa454.
The human genome encodes an order of magnitude more gene expression enhancers than promoters, suggesting that most genes are regulated by the combined action of multiple enhancers. We have previously shown that neighboring estrogen-responsive enhancers exhibit complex synergistic contributions to the production of an estrogenic transcriptional response. Here we sought to determine the molecular underpinnings of this enhancer cooperativity. We generated genetic deletions of four estrogen receptor α (ER) bound enhancers that regulate two genes and found that enhancers containing full estrogen response element (ERE) motifs control ER binding at neighboring sites, while enhancers with pre-existing histone acetylation/accessibility confer a permissible chromatin environment to the neighboring enhancers. Genome engineering revealed that two enhancers with half EREs could not compensate for the lack of a full ERE site within the cluster. In contrast, two enhancers with full EREs produced a transcriptional response greater than the wild-type locus. By swapping genomic sequences, we found that the genomic location of a full ERE strongly influences enhancer activity. Our results lead to a model in which a full ERE is required for ER recruitment, but the presence of a pre-existing permissible chromatin environment can also be needed for estrogen-driven gene regulation to occur.
人类基因组编码的基因表达增强子数量是启动子的数量级，这表明大多数基因是由多个增强子的共同作用来调节的。我们之前已经表明，相邻的雌激素反应增强子对雌激素转录反应的产生表现出复杂的协同作用。在这里，我们试图确定这种增强子协同作用的分子基础。我们生成了四个雌激素受体α（ER）结合增强子的遗传缺失，这些增强子调控两个基因，发现含有完整雌激素反应元件（ERE）基序的增强子控制着相邻位点的 ER 结合，而预先存在的组蛋白乙酰化/可及性增强子赋予了相邻增强子允许的染色质环境。基因组工程表明，两个含有半 ERE 的增强子不能弥补簇内缺乏完整 ERE 位点的情况。相比之下，两个含有完整 ERE 的增强子产生的转录反应大于野生型基因座。通过交换基因组序列，我们发现完整 ERE 的基因组位置强烈影响增强子的活性。我们的结果提出了一个模型，即完整的 ERE 是 ER 招募所必需的，但预先存在的允许染色质环境的存在对于雌激素驱动的基因调控的发生也是必需的。
