From the Institute of Biotechnology, University of Helsinki, P. O. Box 56, 00014 Helsinki.
From the Institute of Biotechnology, University of Helsinki, P. O. Box 56, 00014 Helsinki, the Department of Biosciences, University of Helsinki, P. O. Box 65, 00014 Helsinki.
J Biol Chem. 2014 Jun 6;289(23):16252-61. doi: 10.1074/jbc.M113.541904. Epub 2014 Apr 28.
The Cdk8 (cyclin-dependent kinase 8) module of Mediator integrates regulatory cues from transcription factors to RNA polymerase II. It consists of four subunits where Med12 and Med13 link Cdk8 and cyclin C (CycC) to core Mediator. Here we have investigated the contributions of the Cdk8 module subunits to transcriptional regulation using RNA interference in Drosophila cells. Genome-wide expression profiling demonstrated separation of Cdk8-CycC and Med12-Med13 profiles. However, transcriptional regulation by Cdk8-CycC was dependent on Med12-Med13. This observation also revealed that Cdk8-CycC and Med12-Med13 often have opposite transcriptional effects. Interestingly, Med12 and Med13 profiles overlapped significantly with that of the GATA factor Serpent. Accordingly, mutational analyses indicated that GATA sites are required for Med12-Med13 regulation of Serpent-dependent genes. Med12 and Med13 were also found to be required for Serpent-activated innate immunity genes in defense to bacterial infection. The results reveal a novel role for the Cdk8 module in Serpent-dependent transcription and innate immunity.
细胞周期蛋白依赖性激酶 8（Cdk8）模块的中介体将转录因子的调控信号整合到 RNA 聚合酶 II 上。它由四个亚基组成，其中 Med12 和 Med13 将 Cdk8 和细胞周期蛋白 C（CycC）与核心中介体连接起来。在这里，我们使用果蝇细胞中的 RNA 干扰研究了 Cdk8 模块亚基对转录调控的贡献。全基因组表达谱分析表明 Cdk8-CycC 和 Med12-Med13 谱的分离。然而，Cdk8-CycC 的转录调控依赖于 Med12-Med13。这一观察结果还表明，Cdk8-CycC 和 Med12-Med13 通常具有相反的转录效应。有趣的是，Med12 和 Med13 谱与 GATA 因子 Serpent 的谱重叠显著。因此，突变分析表明，GATA 位点是 Med12-Med13 调节 Serpent 依赖性基因所必需的。还发现 Med12 和 Med13 对于 Serpent 激活的先天免疫基因在抵御细菌感染中的作用是必需的。研究结果揭示了 Cdk8 模块在 Serpent 依赖性转录和先天免疫中的新作用。
