Synergism between p68 RNA helicase and the transcriptional coactivators CBP and p300
Synergism between p68 RNA helicase and the transcriptional coactivators CBP and p300
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DOI：
10.1038/sj.onc.1206067
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发表时间：
2003-01-09
期刊：
影响因子：
8
通讯作者：
Janknecht, R
中科院分区：
文献类型：
--
作者：
Rossow, KL;Janknecht, R
p68 RNA解旋酶参与多种过程，包括RNA二级结构重排、RNA剪接、基因转录和肿瘤发展，但其作用机制尚不清楚。在这项研究中，我们表明，p68主要定位于细胞核，在那里它部分共定位与转录辅激活因子p300。因此，p68和p300，或旁系同源CREB结合蛋白（CBP），共免疫沉淀。类似地，p68和RNA聚合酶II（Pol II）能够在体内相互作用。GST pull-down分析证实了这些体外相互作用，表明p68可以与CBP的几个结构域相互作用，而CBP/p300结合p68的氨基酸176-388，RNA Pol II结合p68的N-末端80个氨基酸。此外，p68刺激CBP的C-末端反式激活结构域介导的转录。p68还能够刺激TPA癌基因应答单位（TORU）启动子活性，并且p300与p68协同作用。另一方面，腺病毒蛋白E1 A对CBP/p300功能的抑制消除了p68对TORU启动子的激活。总之，我们的研究结果表明存在一个多蛋白复合物，其中p68 RNA解旋酶，CBP/p300和RNA Pol II共同促进基因表达。
p68 RNA helicase has been implicated in a variety of processes, including rearrangement of RNA secondary structures, RNA splicing, gene transcription and tumor development, yet its mechanisms of action are not well understood. In this study, we show that p68 is predominantly localized to the cell nucleus, where it partially colocalizes with the transcriptional coactivator p300. Accordingly, p68 and p300, or the paralogous CREB-binding protein (CBP), coimmunoprecipitate. Similarly, p68 and RNA polymerase II (Pol II) are able to interact in vivo. GST pull-down assays confirmed these interactions in vitro, demonstrating that p68 can interact with several domains of CBP, while CBP/p300 bind to amino acids 176-388 of p68 and RNA Pol II binds to the N-terminal 80 amino acids of p68. Furthermore, p68 stimulates transcription mediated by the C-terminal transactivation domain of CBP. p68 is also able to stimulate TPA oncogene responsive unit (TORU) promoter activity, and p300 acts in synergy with p68. On the other hand, suppression of CBP/p300 function by the adenoviral protein E1A abolishes TORU promoter activation by p68. Altogether, our results suggest the existence of a multiprotein complex in which p68 RNA helicase, CBP/p300 and RNA Pol II jointly promote gene expression.