Memişoğlu Gönen, Bohn Stefan, Krogan Nevan J, Haber James E, Ruthenburg Alexander J
Department of Molecular Genetics and Cell Biology, The University of Chicago, IL, 60637, USA.
Department of Biochemistry and Molecular Biology, The University of Chicago, IL, 60637, USA.
bioRxiv. 2025 May 20:2023.02.26.530133. doi: 10.1101/2023.02.26.530133.
The Cdk8 kinase module (CKM) is a non-obligate and dissociable subcomplex of Mediator of transcription, a key regulator of RNA polymerase II (RNAPII). Through a genetic screen in yeast, we discovered a surprising role for Mediator CKM in the DNA damage response (DDR) and mitotic re-entry. Remarkably, we find that a single DNA break is sufficient for CKM-dependent global transcriptional attenuation. Upon DDR activation, the kinase activity of CKM antagonizes RNAPII binding to core Mediator, thereby reducing the transcriptionally-engaged RNAPII pool. This transcriptional attenuation is essential for DDR inactivation and limits the spreading of γ-H2AX into gene bodies. Furthermore, CKM localizes to DNA breaks to impede RNAPII binding. Importantly, we demonstrate that the role of CKM on DDR and transcriptional attenuation is conserved from yeast to mammals, establishing a multifaceted and essential function for CKM in transcriptional regulation of DNA-damage response.
细胞周期蛋白依赖性激酶8激酶模块（CKM）是转录中介体的一个非必需且可解离的亚复合物，转录中介体是RNA聚合酶II（RNAPII）的关键调节因子。通过在酵母中进行的遗传筛选，我们发现中介体CKM在DNA损伤反应（DDR）和有丝分裂重新进入中发挥了惊人的作用。值得注意的是，我们发现单个DNA断裂足以导致依赖CKM的全局转录衰减。在DDR激活后，CKM的激酶活性拮抗RNAPII与核心中介体的结合，从而减少转录参与的RNAPII池。这种转录衰减对于DDR失活至关重要，并限制了γ-H2AX向基因体的扩散。此外，CKM定位于DNA断裂处，以阻止RNAPII结合。重要的是，我们证明了CKM在DDR和转录衰减上的作用从酵母到哺乳动物都是保守的，确立了CKM在DNA损伤反应转录调控中的多方面重要功能。
