Dynamics of the metal-dependent transcription factor complex in vivo at the mouse metallothionein-I promoter.
Dynamics of the metal-dependent transcription factor complex in vivo at the mouse metallothionein-I promoter.
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DOI：
10.1093/nar/gkg913
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发表时间：
2003-12
影响因子：
14.9
通讯作者：
P. J. Daniels;G. Andrews
中科院分区：
文献类型：
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作者：
P. J. Daniels;G. Andrews
利用染色质免疫沉淀（ChIP）检测转录因子与金属硫蛋白i启动子的体内关联。结果表明，c-fos与金属反应元件结合转录因子-1 （MTF-1）一起在锌或镉的作用下迅速募集到该启动子，体内缺锌饮食和培养细胞中降低培养基中锌浓度或长时间暴露于锌后，这种募集在内脏卵黄囊中被逆转。相反，c-jun、USF-1、USF-2和Sp1与该启动子的相互作用是不依赖于金属的。对敲除细胞的研究表明，c-fos募集到MT-I启动子需要MTF-1，但c-fos对于募集MTF-1和金属诱导MT-I基因表达并不是必需的。用MT-I启动子驱动的报告基因稳定转染Hepa细胞的研究表明，USF-1和-2在体内有两个结合位点。Sp1明显与一个单一结合位点（-153 bp上游）相关。此外，金属对c-fos的最大募集需要在- 153bp上游相互作用的序列和/或其他蛋白质。总之，这些研究扩展了我们对MT-I启动子在体内响应金属时形成的转录因子复合物的复杂性和动力学的理解。
The in vivo association of transcription factors with the metallothionein-I promoter was examined using chromatin immunoprecipitation (ChIP) assays. The results demonstrated that c-fos is rapidly recruited along with the metal response element-binding transcription factor-1 (MTF-1) to this promoter in response to zinc or cadmium, and that this recruitment is reversed in the visceral yolk sac by a zinc-deficient diet in vivo, and in cultured cells after lowering the zinc concentration in the medium or during prolonged zinc exposure. In contrast, the interactions of c-jun, USF-1, USF-2 and Sp1 with this promoter are metal-independent. Studies of knockout cells revealed that the recruitment of c-fos to the MT-I promoter requires MTF-1, but that c-fos is not essential for recruitment of MTF-1 and metal-induction of MT-I gene expression. Studies of Hepa cells stably-transfected with reporter genes driven by the MT-I promoter suggested two in vivo binding sites for USF-1 and -2. In contrast, Sp1 was apparently associated with a single binding site (upstream of -153 bp). In addition, maximal recruitment of c-fos by metals required sequences and/or other proteins that interact upstream of -153 bp. In summary, these studies extend our understanding of the complexity and dynamics of the transcription factor complex that forms at the MT-I promoter in vivo in response to metals.