NELF-mediated stalling of Pol II can enhance gene expression by blocking promoter-proximal nucleosome assembly
NELF-mediated stalling of Pol II can enhance gene expression by blocking promoter-proximal nucleosome assembly
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DOI：
10.1101/gad.1643208
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发表时间：
2008-07-15
影响因子：
10.5
通讯作者：
Adelman, Karen
中科院分区：
文献类型：
--
作者：
Gilchrist, Daniel A.;Nechaev, Sergei;Adelman, Karen
负延伸因子（NELF）是一种转录调控复合物，在早期转录延伸过程中诱导RNA聚合酶II（Pol II）停滞，并抑制迄今为止研究的几种基因的表达，包括果蝇Hsp70，哺乳动物原癌基因junB和HIV RNA。为了确定果蝇中NELF靶基因的全谱，我们对耗尽NELF的S2细胞进行了微阵列分析，发现NELF RNAi影响许多参与细胞对刺激反应的快速诱导基因。令人惊讶的是，只有三分之一的NELF靶基因像Hsp70一样被NELF耗尽上调，而大多数靶基因在NELF RNAi后表现出表达水平降低。我们的数据显示，在这后一组基因的存在下，通过保持启动子近端区域周围的容许染色质结构来增强基因表达，并且在这些启动子处的Pol II停滞的损失伴随着核小体占用率的显著增加和组蛋白H3 Lys 4三甲基化的减少。这些研究结果确定了一种新的，积极的作用，停滞的Pol II在调节基因表达，并建议，有一个动态的相互作用之间停滞的Pol II和染色质结构。
The Negative Elongation Factor (NELF) is a transcription regulatory complex that induces stalling of RNA polymerase II (Pol II) during early transcription elongation and represses expression of several genes studied to date, including Drosophila Hsp70, mammalian proto-oncogene junB, and HIV RNA. To determine the full spectrum of NELF target genes in Drosophila, we performed a microarray analysis of S2 cells depleted of NELF and discovered that NELF RNAi affects many rapidly inducible genes involved in cellular responses to stimuli. Surprisingly, only one-third of NELF target genes were, like Hsp70, up-regulated by NELF-depletion, whereas the majority of target genes showed decreased expression levels upon NELF RNAi. Our data reveal that the presence of stalled Pol II at this latter group of genes enhances gene expression by maintaining a permissive chromatin architecture around the promoter-proximal region, and that loss of Pol II stalling at these promoters is accompanied by a significant increase in nucleosome occupancy and a decrease in histone H3 Lys 4 trimethylation. These findings identify a novel, positive role for stalled Pol II in regulating gene expression and suggest that there is a dynamic interplay between stalled Pol II and chromatin structure.