Brunelle Mylène, Nordell Markovits Alexei, Rodrigue Sébastien, Lupien Mathieu, Jacques Pierre-Étienne, Gévry Nicolas
Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 boulevard de l'Université, J1K 2R1, Sherbrooke, Québec, Canada.
Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 boulevard de l'Université, J1K 2R1, Sherbrooke, Québec, Canada Ontario Cancer Institute, Princess Margaret Cancer Centre/University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, M5G 1L7, Canada.
Nucleic Acids Res. 2015 Nov 16;43(20):9742-56. doi: 10.1093/nar/gkv825. Epub 2015 Aug 28.
Gene regulatory programs in different cell types are largely defined through cell-specific enhancers activity. The histone variant H2A.Z has been shown to play important roles in transcription mainly by controlling proximal promoters, but its effect on enhancer functions remains unclear. Here, we demonstrate by genome-wide approaches that H2A.Z is present at a subset of active enhancers bound by the estrogen receptor alpha (ERα). We also determine that H2A.Z does not influence the local nucleosome positioning around ERα enhancers using ChIP sequencing at nucleosomal resolution and unsupervised pattern discovery. We further highlight that H2A.Z-enriched enhancers are associated with chromatin accessibility, H3K122ac enrichment and hypomethylated DNA. Moreover, upon estrogen stimulation, the enhancers occupied by H2A.Z produce enhancer RNAs (eRNAs), and recruit RNA polymerase II as well as RAD21, a member of the cohesin complex involved in chromatin interactions between enhancers and promoters. Importantly, their recruitment and eRNAs production are abolished by H2A.Z depletion, thereby revealing a novel functional link between H2A.Z occupancy and enhancer activity. Taken together, our findings suggest that H2A.Z acts as an important player for enhancer functions by establishing and maintaining a chromatin environment required for RNA polymerase II recruitment, eRNAs transcription and enhancer-promoters interactions, all essential attributes of enhancer activity.
不同细胞类型中的基因调控程序很大程度上是通过细胞特异性增强子的活性来定义的。组蛋白变体H2A.Z已被证明主要通过控制近端启动子在转录中发挥重要作用,但其对增强子功能的影响仍不清楚。在这里,我们通过全基因组方法证明H2A.Z存在于雌激素受体α(ERα)结合的一部分活性增强子中。我们还使用核小体分辨率的ChIP测序和无监督模式发现确定H2A.Z不影响ERα增强子周围的局部核小体定位。我们进一步强调,富含H2A.Z的增强子与染色质可及性、H3K122ac富集和DNA低甲基化相关。此外,在雌激素刺激下,被H2A.Z占据的增强子产生增强子RNA(eRNA),并募集RNA聚合酶II以及RAD21,RAD21是黏连蛋白复合物的成员,参与增强子与启动子之间的染色质相互作用。重要的是,它们的募集和eRNA产生因H2A.Z缺失而被消除,从而揭示了H2A.Z占据与增强子活性之间的新功能联系。综上所述,我们的研究结果表明,H2A.Z通过建立和维持RNA聚合酶II募集、eRNA转录以及增强子-启动子相互作用所需的染色质环境,在增强子功能中发挥重要作用,而这些都是增强子活性的基本特征。