It is unclear how various factors functioning in the transcriptional elongation by RNA polymerase II (RNA Pol II) cooperatively regulate pause/release and productive elongation in living cells. Using an acute protein-depletion approach, we report that SPT6 depletion results in the release of paused RNA Pol II into gene bodies through an impaired recruitment of PAF1C. Short genes demonstrate a release with increased mature transcripts, whereas long genes are released but fail to yield mature transcripts, due to a reduced processivity resulting from both SPT6 and PAF1C loss. Unexpectedly, SPT6 depletion causes an association of NELF with the elongating RNA Pol II on gene bodies, without any observed functional significance on transcriptional elongation pattern, arguing against a role for NELF in keeping RNA Pol II in the paused state. Furthermore, SPT6 depletion impairs heat-shock-induced pausing, pointing to a role for SPT6 in regulating RNA Pol II pause/release through PAF1C recruitment.

目前尚不清楚 RNA 聚合酶 II (RNA Pol II) 转录延伸中发挥作用的各种因素如何协同调节活细胞中的暂停/释放和有效延伸。使用急性蛋白质消耗方法，我们报告 SPT6 消耗导致 PAF1C 招募受损，导致暂停的 RNA Pol II 释放到基因体中。短基因表现出随着成熟转录本的增加而释放，而长基因被释放但未能产生成熟转录本，因为 SPT6 和 PAF1C 损失导致持续合成能力降低。出乎意料的是，SPT6 缺失导致 NELF 与基因体上延伸的 RNA Pol II 相关，但在转录延伸模式上没有观察到任何功能意义，这反对 NELF 在保持 RNA Pol II 处于暂停状态中的作用。此外，SPT6 的耗竭会损害热休克引起的暂停，表明 SPT6 通过 PAF1C 募集在调节 RNA Pol II 暂停/释放中发挥作用。