Repression of CDK1 and other genes with CDE and CHR promoter elements during DNA damage-induced G2/M arrest in human cells
Repression of CDK1 and other genes with CDE and CHR promoter elements during DNA damage-induced G2/M arrest in human cells
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DOI：
10.1128/mcb.20.7.2358-2366.2000
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发表时间：
2000-04-01
影响因子：
5.3
通讯作者：
Porter, ACG
中科院分区：
文献类型：
--
作者：
Badie, C;Itzhaki, JE;Porter, ACG
有丝分裂的进入是由细胞周期蛋白依赖性激酶CDK1控制的，并且可以在DNA损伤的反应中延迟。在某些系统中，这种G(2)/M阻滞已被证明反映了CDK1上抑制性磷酸化位点的稳定。在人类细胞中，完全G(2)阻滞似乎涉及其他机制。我们描述了人类细胞DNA损伤后CDK1蛋白和mRNA水平的长时间下调（bbb6天），这种基因表达沉默在原代人成纤维细胞和两种具有功能p53的细胞系中观察到，但在p53不活跃的HeLa细胞中没有观察到。沉默伴随着G中细胞的积累(2)，而此时CDK1的表达通常是最大的。CDK1启动子中顺式作用元件（CDE和CHR）的突变破坏了这种反应，表明沉默发生在转录水平。这些元件先前与G(1)期间的转录抑制有关，这种抑制通常在细胞进入S和G(2)时被解除。有趣的是，我们发现其他基因，包括CDC25C、细胞周期蛋白A2、细胞周期蛋白B1、CENP-A和拓扑异构酶II α的基因，通常在G中优先表达(2)，其启动子区域包括假定的CDE和CHR元件，也在响应DNA损伤时下调。这些数据，以及其他研究小组的数据，支持p53依赖性，DNA损伤激活途径的存在，导致CHR-和cde介导的各种G(2)特异性基因的转录抑制。这种途径可能是DNA损伤后G(2)阻滞持续时间所必需的。
Entry into mitosis is controlled by the cyclin-dependent kinase CDK1 and can be delayed in response to DNA damage. In some systems, such G(2)/M arrest has been shown to reflect the stabilization of inhibitory phosphorylation sites on CDK1. In human cells, full G(2) arrest appears to involve additional mechanisms. We describe here the prolonged (>6 day) downregulation of CDK1 protein and mRNA levels following DNA damage in human cells, This silencing of gene expression is observed in primary human fibroblasts and in two cell lines with functional p53 but not in HeLa cells, where p53 is inactive. Silencing is accompanied by the accumulation of cells in G(2), when CDK1 expression is normally maximal. The response is impaired by mutations in cis-acting elements (CDE and CHR) in the CDK1 promoter, indicating that silencing occurs at the transcriptional level. These elements have previously been implicated in the repression of transcription during G(1) that is normally lifted as cells progress into S and G(2). Interestingly, we find that other genes, including those for CDC25C, cyclin A2, cyclin B1, CENP-A and topoisomerase II alpha, that are normally expressed preferentially in G(2) and whose promoter regions include putative CDE and CHR elements are also downregulated in response to DNA damage. These data, together with those of other groups, support the existence of a p5.3-dependent, DNA damage-activated pathway leading to CHR- and CDE-mediated transcriptional repression of various G(2)-specific genes. This pathway may be required for sustained periods of G(2) arrest following DNA damage.