Cytomegalovirus IE2 protein stimulates interleukin 1beta gene transcription via tethering to Spi-1/PU.1.
Cytomegalovirus IE2 protein stimulates interleukin 1beta gene transcription via tethering to Spi-1/PU.1.
复制标题
巨细胞病毒 IE2 蛋白通过与 Spi-1/PU.1 结合刺激白细胞介素 1β 基因转录。
DOI：
10.1128/mcb.19.10.6803
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发表时间：
1999
影响因子：
5.3
通讯作者：
Auron,PE
中科院分区：
文献类型：
--
作者：
Wara-aswapati,N;Yang,Z;Waterman,WR;Koyama,Y;Tetradis,S;Choy,BK;Webb,AC;Auron,PE
人类白细胞介素1β原（il 1b）基因的有效诱导通常需要一个远上游的诱导增强子，以及一个位于-131和+12之间的最小启动子。转录因子Spi-1（也称为PU.1）是表达所必需的，并与最小启动子结合，从而提供了一个必需的转录激活结构域。相反，人巨细胞病毒（HCMV）感染可以通过表达立即早期（IE）病毒蛋白强烈激活IL 1b，并消除了对上游增强子的需求。Spi-1在此过程中被间接地牵连为宿主因子。我们在这里报告的Spi-1的直接参与HCMV激活ofil 1b的分子基础。Spi-1缺陷型HeLa细胞的转染证明了IE活性需要Spi-1，并且需要比不存在IE蛋白时所需的启动子更短的启动子（-59至+12）。此外，与绝对需要Spi-1翼螺旋-转角-螺旋（wHTH）DNA结合结构域和大部分Spi-1 β的正常增强子依赖性表达相反，在IE蛋白存在下的il 1b表达不需要Spi-1 β，其起协同作用。此外，我们证明，一个单一的IE蛋白，IE 2，是至关重要的诱导ofil 1b。蛋白质-蛋白质相互作用实验表明，Spi-1的wHTH结构域内的翼基序直接招募IE 2。反过来，IE 2与Spi-1机翼物理关联，并需要IE 2的至少一个区域的完整性。功能分析表明，该区域和羧基末端的酸性磷酸酶都是IE 2功能所必需的。因此，我们提出了一种蛋白质栓系的反式激活机制，其中il 1b启动子结合的Spi-1 wHTH栓系IE 2，IE 2提供了一个启动子，导致il 1b的反式激活。
Potent induction of the gene coding for human prointerleukin 1β (il1b) normally requires a far-upstream inducible enhancer in addition to a minimal promoter located between positions −131 and +12. The transcription factor Spi-1 (also called PU.1) is necessary for expression and binds to the minimal promoter, thus providing an essential transcription activation domain (TAD). In contrast, infection by human cytomegalovirus (HCMV) can strongly activateil1bvia the expression of immediate early (IE) viral proteins and eliminates the requirement for the upstream enhancer. Spi-1 has been circumstantially implicated as a host factor in this process. We report here the molecular basis for the direct involvement of Spi-1 in HCMV activation ofil1b. Transfection of Spi-1-deficient HeLa cells demonstrated both the requirement of Spi-1 for IE activity and the need for a shorter promoter (−59 to +12) than that required in the absence of IE proteins. Furthermore, in contrast to normal, enhancer-dependentil1bexpression, which absolutely requires both the Spi-1 winged helix-turn-helix (wHTH) DNA-binding domain and the majority of the Spi-1 TAD,il1bexpression in the presence of IE proteins does not require the Spi-1 TAD, which plays a synergistic role. In addition, we demonstrate that a single IE protein, IE2, is critical for the induction ofil1b. Protein-protein interaction experiments revealed that the wing motif within the Spi-1 wHTH domain directly recruits IE2. In turn, IE2 physically associates with the Spi-1 wing and requires the integrity of at least one region of IE2. Functional analysis demonstrates that both this region and a carboxy-terminal acidic TAD are required for IE2 function. Therefore, we propose a protein-tethered transactivation mechanism in which theil1bpromoter-bound Spi-1 wHTH tethers IE2, which provides a TAD, resulting in the transactivation ofil1b.