Ramachandran Srinivas, Henikoff Steven
Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Seattle, WA 98109, USA.
Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Seattle, WA 98109, USA.
Cell. 2016 Apr 21;165(3):580-92. doi: 10.1016/j.cell.2016.02.062. Epub 2016 Apr 7.
Every nucleosome across the genome must be disrupted and reformed when the replication fork passes, but how chromatin organization is re-established following replication is unknown. To address this problem, we have developed Mapping In vivo Nascent Chromatin with EdU and sequencing (MINCE-seq) to characterize the genome-wide location of nucleosomes and other chromatin proteins behind replication forks at high temporal and spatial resolution. We find that the characteristic chromatin landscape at Drosophila promoters and enhancers is lost upon replication. The most conspicuous changes are at promoters that have high levels of RNA polymerase II (RNAPII) stalling and DNA accessibility and show specific enrichment for the BRM remodeler. Enhancer chromatin is also disrupted during replication, suggesting a role for transcription factor (TF) competition in nucleosome re-establishment. Thus, the characteristic nucleosome landscape emerges from a uniformly packaged genome by the action of TFs, RNAPII, and remodelers minutes after replication fork passage.
当复制叉通过时，基因组中的每个核小体都必须被破坏并重新形成，但复制后染色质组织是如何重新建立的尚不清楚。为了解决这个问题，我们开发了用EdU和测序在体内映射新生染色质（MINCE-seq）技术，以高时空分辨率表征复制叉后核小体和其他染色质蛋白在全基因组范围内的位置。我们发现，果蝇启动子和增强子处的特征性染色质景观在复制时会消失。最显著的变化发生在具有高水平RNA聚合酶II（RNAPII）停滞和DNA可及性且对BRM重塑因子有特异性富集的启动子上。增强子染色质在复制过程中也会被破坏，这表明转录因子（TF）竞争在核小体重新建立中起作用。因此，在复制叉通过几分钟后通过TF、RNAPII和重塑因子的作用，特征性核小体景观从均匀包装的基因组中显现出来。
