Transcription progression is governed by multitasking regulators including SPT5, an evolutionarily conserved factor implicated in virtually all transcriptional steps from enhancer activation to termination. Here we utilize a rapid degradation system and reveal crucial functions of SPT5 in maintaining cellular and chromatin RNA polymerase II (Pol II) levels. Rapid SPT5 depletion causes a pronounced reduction of paused Pol II at promoters and enhancers, distinct from negative elongation factor (NELF) degradation resulting in short-distance paused Pol II redistribution. Most genes exhibit downregulation, but not upregulation, accompanied by greatly impaired transcription activation, altered chromatin landscape at enhancers, and severe Pol II processivity defects at gene bodies. Phosphorylation of an SPT5 linker at serine 666 potentiates pause release and is antagonized by Integrator-PP2A (INTAC) targeting SPT5 and Pol II, while phosphorylation of the SPT5 C-terminal region links to 3′ end termination. Our findings position SPT5 as an essential positive regulator of global transcription.

转录进程由多任务调节器控制，包括 SPT5，这是一种进化上保守的因子，涉及从增强子激活到终止的几乎所有转录步骤。在这里，我们利用快速降解系统并揭示 SPT5 在维持细胞和染色质 RNA 聚合酶 II (Pol II) 水平方面的关键功能。快速 SPT5 消耗导致启动子和增强子处暂停的 Pol II 显着减少，这与负延伸因子 (NELF) 降解导致短距离暂停 Pol II 重新分布不同。大多数基因表现出下调，但没有上调，伴随着转录激活严重受损，增强子染色质景观改变，以及基因体严重的 Pol II 合成能力缺陷。SPT5 接头在丝氨酸 666 处的磷酸化增强了暂停释放，并被针对 SPT5 和 Pol II 的 Integrator-PP2A (INTAC) 拮抗，而 SPT5 C 末端区域的磷酸化与 3' 末端终止有关。我们的研究结果将 SPT5 定位为全球转录的重要正调节因子。