Transcriptional activity of Sp1 is regulated by molecular interactions between the zinc finger DNA binding domain and the inhibitory domain with corepressors, and this interaction is modulated by MEK
Transcriptional activity of Sp1 is regulated by molecular interactions between the zinc finger DNA binding domain and the inhibitory domain with corepressors, and this interaction is modulated by MEK
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DOI：
10.1074/jbc.m414134200
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发表时间：
2005-07-29
影响因子：
4.8
通讯作者：
Hur, MW
中科院分区：
文献类型：
--
作者：
Lee, JA;Suh, DC;Hur, MW
Sp1通过位于近端启动子或增强子中的GC盒激活许多细胞和病毒基因的转录。Sp1由几个功能结构域组成，如抑制结构域（ID）、两个富含丝氨酸/苏氨酸的结构域、两个富含谷氨酰胺的结构域、三个C2 H2型锌指DNA结合结构域（ZFDBD）和一个C末端D结构域。ZDDBD是Sp家族转录因子中最保守的结构域，在GC盒识别中起着关键作用。在这项研究中，我们研究了发生在Sp1 ZFDBD和Sp1 ID的蛋白质-蛋白质相互作用，以及控制相互作用的分子机制。我们的研究结果发现，Sp1 ZFDBD和Sp1 ID抑制转录，一旦他们被靶向的pGal 4 UAS报告融合基因系统的近端启动子，这表明与阻遏分子的分子相互作用。事实上，哺乳动物双杂交试验，GST融合蛋白下拉试验和免疫共沉淀试验表明，Sp1 ZFDBD和Sp1 ID能够与辅阻遏蛋白，如SMRT，NcoR和BCoR相互作用。分子间的相互作用似乎受MAP激酶/ERK激酶激酶（MEK）的调节。Sp1 ID和辅阻遏物之间的分子相互作用可能解释了Sp1在某些情况下作为阻遏物的作用。siRNA诱导的核心加压子的降解导致Sp1依赖性转录的上调。辅阻遏物的细胞环境和辅阻遏物与Sp1 ZFDBD或Sp1 ID之间的分子相互作用的调节可能在控制Sp1活性中是重要的。
Sp1 activates the transcription of many cellular and viral genes with the GC-box in either the proximal promoter or the enhancer. Sp1 is composed of several functional domains, such as the inhibitory domain ( ID), two serine/threonine-rich domains, two glutamine-rich domains, three C2H2-type zinc finger DNA binding domains (ZFDBD), and a C-terminal D domain. The ZDDBD is the most highly conserved domain among the Sp-family transcription factors and plays a critical role in GC-box recognition. In this study, we investigated the protein-protein interactions occurring at the Sp1ZFDBD and the Sp1ID, and the molecular mechanisms controlling the interaction. Our results found that Sp1ZFDBD and Sp1ID repressed transcription once they were targeted to the proximal promoter of the pGal4 UAS reporter fusion gene system, suggesting molecular interaction with the repressor molecules. Indeed, mammalian two-hybrid assays, GST fusion protein pull-down assays, and co-immunoprecipitation assays showed that Sp1ZFDBD and Sp1ID are able to interact with corepressor proteins such as SMRT, NcoR, and BCoR. The molecular interactions appear to be regulated by MAP kinase/Erk kinase kinase (MEK). The molecular interactions between Sp1ID and the corepressor might explain the role of Sp1 as a repressor under certain circumstances. The siRNA-induced degradation of the core-pressors resulted in an up-regulation of Sp1-dependent transcription. The cellular context of the corepressors and the regulation of molecular interaction between corepressors and Sp1ZFDBD or Sp1ID might be important in controlling Sp1 activity.