Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, Vienna, Austria.
CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
Mol Cell. 2019 Nov 7;76(3):485-499.e8. doi: 10.1016/j.molcel.2019.07.034. Epub 2019 Sep 5.
Transcriptional responses to external stimuli remain poorly understood. Using global nuclear run-on followed by sequencing (GRO-seq) and precision nuclear run-on sequencing (PRO-seq), we show that CDK8 kinase activity promotes RNA polymerase II pause release in response to interferon-γ (IFN-γ), a universal cytokine involved in immunity and tumor surveillance. The Mediator kinase module contains CDK8 or CDK19, which are presumed to be functionally redundant. We implemented cortistatin A, chemical genetics, transcriptomics, and other methods to decouple their function while assessing enzymatic versus structural roles. Unexpectedly, CDK8 and CDK19 regulated different gene sets via distinct mechanisms. CDK8-dependent regulation required its kinase activity, whereas CDK19 governed IFN-γ responses through its scaffolding function (i.e., it was kinase independent). Accordingly, CDK8, not CDK19, phosphorylates the STAT1 transcription factor (TF) during IFN-γ stimulation, and CDK8 kinase inhibition blocked activation of JAK-STAT pathway TFs. Cytokines such as IFN-γ rapidly mobilize TFs to "reprogram" cellular transcription; our results implicate CDK8 and CDK19 as essential for this transcriptional reprogramming.
细胞对外部刺激的转录反应仍知之甚少。本研究采用全局核转录延伸 followed by sequencing (GRO-seq) 和精确核转录延伸测序 (PRO-seq)，发现 CDK8 激酶活性促进 RNA 聚合酶 II 对干扰素-γ（IFN-γ）的暂停释放，IFN-γ 是一种参与免疫和肿瘤监测的通用细胞因子。中介激酶模块包含 CDK8 或 CDK19，它们被认为具有功能冗余性。本研究通过实施皮质抑素 A、化学遗传学、转录组学和其他方法来分离它们的功能，同时评估酶与结构的作用。出乎意料的是，CDK8 和 CDK19 通过不同的机制调节不同的基因集。CDK8 依赖性调节需要其激酶活性，而 CDK19 通过其支架功能（即激酶非依赖性）来控制 IFN-γ 反应。相应地，CDK8 而非 CDK19 在 IFN-γ 刺激时磷酸化 STAT1 转录因子（TF），CDK8 激酶抑制阻断了 JAK-STAT 途径 TF 的激活。IFN-γ 等细胞因子可迅速动员 TF 来“重编程”细胞转录；本研究结果表明 CDK8 和 CDK19 是这种转录重编程所必需的。
