Negative regulation of the RelA/p65 transactivation function by the product of the DEK proto-oncogene
Negative regulation of the RelA/p65 transactivation function by the product of the DEK proto-oncogene
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DOI：
10.1074/jbc.m600915200
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发表时间：
2006-09-15
影响因子：
4.8
通讯作者：
Ashburner, Brian P.
中科院分区：
文献类型：
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作者：
Sammons, Morgan;Wan, Shan Shan;Ashburner, Brian P.
核因子-kappaB介导的转录激活在多个水平上受到控制，包括与共调节蛋白的相互作用。以p65C末端反式激活结构域为诱饵，进行细胞质双杂交筛选，鉴定原癌基因dek的产物，寻找新的调控核因子-kappaB激活的蛋白。DEK是一种普遍存在的核蛋白，与多种类型的癌症和自身免疫性疾病有关。DEK似乎在几个核过程中发挥作用，包括转录抑制和染色质结构的调节。我们的数据表明，DEK作为转录辅阻遏子来抑制核因子-kappaB的活性。DEK的表达阻断了p65介导的依赖于核因子-kappa B的报告基因的激活，也抑制了肿瘤坏死因子α诱导的报告基因的激活。染色质免疫沉淀(ChIP)分析表明，DEK与未处理细胞中受核因子-kappa B调控的cIAP2和IL-8基因的启动子结合，并在与核因子-kappaB结合时解离这些启动子。此外，在DEK-/-细胞中，依赖于NF-kappa B的报告基因以及由NF-kappa B调节的MCP-1和I kappa Bα基因的表达水平比野生型细胞高。对这些启动子的芯片分析表明，p65的结合增强和延长，P/CaF共激活因子的募集增加。总体而言，这些数据提供了进一步的证据，证明DEK具有负向调控转录的功能。
NF-kappa B-mediated transcriptional activation is controlled at several levels including interaction with coregulatory proteins. To identify new proteins capable of modulating NF-kappa B-mediated activation, a cytoplasmic two-hybrid screen was performed using the p65 C-terminal transactivation domain as bait and identified the product of the DEK proto-oncogene. DEK is a ubiquitous nuclear protein that has been implicated in several types of cancer and autoimmune diseases. DEK appears to function in several nuclear processes including transcriptional repression and modulation of chromatin structure. Our data indicate that DEK functions as a transcriptional corepressor to repress NF-kappa B activity. DEK expression blocked p65-mediated activation of an NF-kappa B-dependent reporter gene and also inhibited TNF alpha-induced activation of the reporter gene. Chromatin Immunoprecipitation (ChIP) assays showed that DEK associates with the promoters of the NF-kappa B-regulated cIAP2 and IL-8 genes in untreated cells and dissociates from these promoters upon NF-kappa B-binding in response to TNF alpha treatment. Moreover, the expression levels of an NF-kappa B-dependent reporter gene as well as the NF-kappa B-regulated Mcp-1 and I kappa B alpha genes is increased in DEK-/- cells compared with wild-type cells. ChIP assays on these promoters show enhanced and prolonged binding of p65 and increased recruitment of the P/CAF coactivator. Overall, these data provide further evidence that DEK functions to negatively regulate transcription.