Recruitment of SWI/SNF to the human immunodeficiency virus type 1 promoter
Recruitment of SWI/SNF to the human immunodeficiency virus type 1 promoter
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DOI：
10.1128/mcb.24.1.389-397.2004
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发表时间：
2004-01-01
影响因子：
5.3
通讯作者：
Tremethick, DJ
中科院分区：
文献类型：
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作者：
Henderson, A;Holloway, A;Tremethick, DJ
在人类免疫缺陷病毒1型（HIV-1）整合到宿主细胞的基因组中之后，5'长末端重复序列（LTR）被包装到高度特异性的染色质结构中，所述染色质结构由相对于调节前病毒的转录活性的重要DNA序列元件定位的核小体阵列组成。虽然已经证明几种宿主细胞因子对染色质重塑和/或基础转录是重要的，但是没有发现解除由nuc-1（阻碍转录起始位点的定位核小体）施加的转录抑制的特异性机制。我们寻找以佛波酯依赖方式与HIV-1启动子这一区域相关的蛋白因子。我们在这里报告，ATF-3，JunB和BRG-1（2-MDa人染色质重塑机器SWI/SNF的ATP酶亚基）在Jurkat T细胞中被募集到nuc-1的3'边界后，佛波醇肉豆蔻酸酯乙酸酯刺激。对从Jurkat T细胞制备的核提取物中BRG-1的募集和用纯化组分重建体外系统的分析表明，ATF-3负责将人SWI/SNF（hSWI/SNF）靶向HIV-1启动子。重要的是，这种hSWI/SNF的募集需要HMGA 1蛋白。免疫沉淀实验进一步支持了这一结论，表明BRG-1和ATF-3可以在同一复合物中共同存在。虽然ATF-3在BRG-1特异性靶向HIV-1启动子中发挥作用，但BRG-1和染色质之间稳定结合的维持似乎依赖于组蛋白乙酰化。通过将BRG-1添加回BRG-1缺陷细胞系（C33 A细胞），我们证明了阿司他汀A以依赖于BRG-1募集的方式强烈诱导5 '-LTR驱动的报告基因转录。
Following human immunodeficiency virus type 1 (HIV-1) integration into the host cell's genome, the 5' long terminal repeat (LTR) is packaged into a highly specific chromatin structure comprised of an array of nucleosomes positioned with respect to important DNA sequence elements that regulate the transcriptional activity of the provirus. While several host cell factors have been shown to be important for chromatin remodeling and/or basal transcription, no specific mechanism that relieves the transcriptional repression imposed by nuc-1, a positioned nucleosome that impedes the start site of transcription, has been found. Since phorbol esters cause the rapid disruption of nuc-1 and markedly stimulate HIV-1 transcription, we looked for protein factors that associate with this region of the HIV-1 promoter in a phorbol-ester-dependent manner. We report here that ATF-3, JunB, and BRG-1 (the ATPase subunit of the 2-MDa human chromatin remodeling machine SWI/SNF) are recruited to the 3' boundary of nuc-1 following phorbol myristate acetate stimulation in Jurkat T cells. Analysis of the recruitment of BRG-1 in nuclear extracts prepared from Jurkat T cells and reconstitution of an in vitro system with purified components demonstrate that ATF-3 is responsible for targeting human SWI/SNF (hSWI/SNF) to the HIV-1 promoter. Importantly, this recruitment of hSWI/SNF required HMGA1 proteins. Further support for this conclusion comes from immunoprecipitation experiments showing that BRG-1 and ATF-3 can exist together in the same complex. Although ATF-3 clearly plays a role in the specific targeting of BRG-1 to the HIV-1 promoter, the maintenance of a stable association between BRG-1 and chromatin appears to be dependent upon histone acetylation. By adding BRG-1 back into a BRG-1-deficient cell line (C33A cells), we demonstrate that trichostatin A strongly induces the 5'-LTR-driven reporter transcription in a manner that is dependent upon BRG-1 recruitment.