Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
Swiss Institute of Bioinformatics, Basel, Switzerland.
Nat Genet. 2021 Mar;53(3):279-287. doi: 10.1038/s41588-020-00768-w. Epub 2021 Feb 8.
Chromatin accessibility is a hallmark of regulatory regions, entails transcription factor (TF) binding and requires nucleosomal reorganization. However, it remains unclear how dynamic this process is. In the present study, we use small-molecule inhibition of the catalytic subunit of the mouse SWI/SNF remodeler complex to show that accessibility and reduced nucleosome presence at TF-binding sites rely on persistent activity of nucleosome remodelers. Within minutes of remodeler inhibition, accessibility and TF binding decrease. Although this is irrespective of TF function, we show that the activating TF OCT4 (POU5F1) exhibits a faster response than the repressive TF REST. Accessibility, nucleosome depletion and gene expression are rapidly restored on inhibitor removal, suggesting that accessible chromatin is regenerated continuously and in a largely cell-autonomous fashion. We postulate that TF binding to chromatin and remodeler-mediated nucleosomal removal do not represent a stable situation, but instead accessible chromatin reflects an average of a dynamic process under continued renewal.
染色质可及性是调控区域的一个标志,需要转录因子(TF)结合,并需要核小体重排。然而,目前尚不清楚这个过程的动态性如何。在本研究中,我们使用小分子抑制小鼠 SWI/SNF 重塑复合物的催化亚基,以显示 TF 结合位点的可及性和核小体减少依赖于核小体重塑剂的持续活性。在重塑剂抑制后的几分钟内,可及性和 TF 结合降低。尽管这与 TF 功能无关,但我们表明激活 TF OCT4(POU5F1)的反应速度快于抑制性 TF REST。抑制剂去除后,可及性、核小体耗竭和基因表达迅速恢复,表明可及染色质以连续和主要是细胞自主的方式不断再生。我们假设 TF 与染色质的结合和重塑剂介导的核小体去除并不代表一种稳定的情况,而是可及染色质反映了在持续更新下的一个动态过程的平均值。