HMG-I(Y) and the CBP/p300 coactivator are essential for human papillomavirus type 18 enhanceosome transcriptional activity
HMG-I(Y) and the CBP/p300 coactivator are essential for human papillomavirus type 18 enhanceosome transcriptional activity
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DOI：
10.1128/mcb.23.7.2329-2340.2003
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发表时间：
2003-04-01
影响因子：
5.3
通讯作者：
Thierry, F
中科院分区：
文献类型：
--
作者：
Bouallaga, I;Teissier, S;Thierry, F
一种强大的上皮特异性增强子驱动人类乳头状瘤病毒18型(HPV18)癌基因的转录。它的活性取决于高阶核蛋白复合体(增强体)的形成，该复合体涉及序列特异性的JunB/Fra2转录因子和HNIG-I(Y)结构蛋白。在这里，我们发现从HeLa细胞核提取的蛋白质覆盖了几乎所有的HPV18增强子序列，并且它包含七个与纯化的HMG-I(Y)蛋白的结合位点，这为紧密的核蛋白结构提供了证据。HMG-I(Y)与HeLa核提取物中的AP1异源二聚体与核心增强体重叠部位的结合是协同的。对于增强子功能，这个特定的HMG-I(Y)结合位点的完整性与AP1结合位点一样重要，表明这个结构蛋白所起的基础作用。我们证明了CBP/p300共激活子是由HPV18增强体招募的，并且它对转录激活是有限的，因为它被腺病毒E1A蛋白和JunB/Fra2阳性因子过度隔离。我们通过对HeLa细胞中的HPV18序列进行染色质免疫沉淀，证明了JunB和p300在体内参与了HPV18的转录。
A strong epithelial specific enhancer drives transcription of the human papillornavirus type 18 (HPV18) oncogenes. Its activity depends on the formation of a higher-order nucleoprotein complex (enhanceosome) involving the sequence-specific JunB/Fra2 transcription factor and the HNIG-I(Y) architectural protein. Here we show that proteins from HeLa cell nuclear extract cover almost all of the HPV18 enhancer sequences and that it contains seven binding sites for the purified HMG-I(Y) protein, providing evidence for a tight nucleoprotein structure. Binding of HMG-I(Y) and the AP1 heterodimer from HeLa nuclear extract to overlapping sites of the core enhanceosome is cooperative. The integrity of this specific HMG-I(Y) binding site is as essential as the AP1 binding site for the enhancer function, indicating the fundamental role played by this architectural protein. We demonstrate that the CBP/p300 coactivator is recruited by the HPV18 enhanceosome and that it is limiting for transcriptional activation, since it is sequestered by the adenovirus E1A protein and by the JunB/Fra2 positive factor in excess. We show the involvement of JunB and p300 in vivo in the HPV18 transcription by chromatin immunoprecipitation of HPV18 sequences in HeLa cells.