The Cyclin K/Cdk12 complex maintains genomic stability via regulation of expression of DNA damage response genes
The Cyclin K/Cdk12 complex maintains genomic stability via regulation of expression of DNA damage response genes
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DOI：
10.1101/gad.16962311
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发表时间：
2011-10-15
影响因子：
10.5
通讯作者：
Peterlin, B. Matija
中科院分区：
文献类型：
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作者：
Blazek, Dalibor;Kohoutek, Jiri;Peterlin, B. Matija
各种细胞周期蛋白依赖性激酶（Cdk）复合物已被牵连在转录的调节。在这项研究中，我们确定了一个70 kDa的细胞周期蛋白K（CycK），结合Cdk 12和Cdk 13，形成两个不同的复合物（CycK/Cdk 12或CycK/Cdk 13）在人类细胞。CycK/Cdk 12复合物调节RNA聚合酶II C-末端结构域中Ser 2的磷酸化和一小部分人类基因的表达，如表达微阵列所示。CycK/Cdk 12的缺失导致具有大量外显子的主要长基因的表达降低。最突出的下调基因组是DNA损伤反应基因，包括基因组稳定性的关键调节因子：BRCA 1（乳腺癌和卵巢癌1型易感蛋白1），ATR（共济失调毛细血管扩张和Rad 3相关），FANCI和FANCD 2。我们发现，CycK/Cdk 12，而不是CycK/Cdk 13，是必要的，他们的表达。核运行的分析和染色质免疫沉淀与RNA聚合酶II的BRCA 1和FANCI基因表明在CycK/Cdk 12的情况下的转录缺陷。与这些发现一致，没有CycK/Cdk 12的细胞诱导自发DNA损伤，并且对各种DNA损伤剂敏感。我们的结论是，通过调节DNA损伤反应基因的表达，CycK/Cdk 12保护细胞免受基因组不稳定。CycK在体内对生物体的重要作用进一步得到了小鼠中CycK基因失活导致早期胚胎致死的结果的支持。
Various cyclin-dependent kinase (Cdk) complexes have been implicated in the regulation of transcription. In this study, we identified a 70-kDa Cyclin K (CycK) that binds Cdk12 and Cdk13 to form two different complexes (CycK/Cdk12 or CycK/Cdk13) in human cells. The CycK/Cdk12 complex regulates phosphorylation of Ser2 in the C-terminal domain of RNA polymerase II and expression of a small subset of human genes, as revealed in expression microarrays. Depletion of CycK/Cdk12 results in decreased expression of predominantly long genes with high numbers of exons. The most prominent group of down-regulated genes are the DNA damage response genes, including the critical regulators of genomic stability: BRCA1 (breast and ovarian cancer type 1 susceptibility protein 1), ATR (ataxia telangiectasia and Rad3-related), FANCI, and FANCD2. We show that CycK/Cdk12, rather than CycK/Cdk13, is necessary for their expression. Nuclear run-on assays and chromatin immunoprecipitations with RNA polymerase II on the BRCA1 and FANCI genes suggest a transcriptional defect in the absence of CycK/Cdk12. Consistent with these findings, cells without CycK/Cdk12 induce spontaneous DNA damage and are sensitive to a variety of DNA damage agents. We conclude that through regulation of expression of DNA damage response genes, CycK/Cdk12 protects cells from genomic instability. The essential role of CycK for organisms in vivo is further supported by the result that genetic inactivation of CycK in mice causes early embryonic lethality.