Down-modulation of interleukin-6 gene expression by 17 beta-estradiol in the absence of high affinity DNA binding by the estrogen receptor.
Down-modulation of interleukin-6 gene expression by 17 beta-estradiol in the absence of high affinity DNA binding by the estrogen receptor.
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DOI：
10.1016/s0021-9258(18)99966-7
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发表时间：
1994-04
期刊：
影响因子：
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通讯作者：
A. Ray;K. E. Prefontaine;P. Ray
中科院分区：
文献类型：
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作者：
A. Ray;K. E. Prefontaine;P. Ray
在用野生型（wt）或突变型雌激素受体（ER）表达载体转染的细胞中研究了17 β-雌二醇（E2）对白细胞介素-6（IL-6）启动子的抑制机制。在瞬时转染实验中，IL-1诱导的IL-6启动子的激活被wt ER有效抑制。然而，携带突变的雌激素受体内或重叠的DNA结合域没有抑制IL-6启动子活性。缺乏N-末端反式激活因子功能-1但保留C-末端反式激活因子功能-2的突变受体也抑制IL-6启动子的激活。我们最近的实验表明，IL-6启动子中的核因子（NF）-IL 6和NF-κ B位点都需要被IL-1激活。我们现在表明，激活的IL-6启动子，引发的NF-IL 6和NF-κ B B的p65亚基的组合，可以抑制野生型受体，但不包含在其DNA结合结构域的突变的受体。尽管ER的DNA结合结构域内的缺失废除了受体的阻遏物功能，但嵌合受体ER-GR CAS 1（其中ER的DNA结合结构域与糖皮质激素受体的互补区域交换）保留了对IL-6启动子的抑制作用。这是在相反的绝对依赖于ER对自己的DNA结合域的激活典型的雌激素反应元件的启动子，如以前报道的其他研究人员。此外，ER和E2的组合对IL-6启动子的抑制，与相同组合对雌激素应答元件的激活不同，似乎不是通过受体与启动子的高亲和力结合介导的。在功能实验中，ER的反式激活因子功能完全被p65的过表达抑制，并且在较小程度上被NF-IL 6的过表达抑制。这些结果表明，ER可能抑制基因表达的情况下，高亲和力的DNA结合。
The mechanism of repression of the interleukin-6 (IL-6) promoter by 17 beta-estradiol (E2) was investigated in cells transfected with wild-type (wt) or mutant estrogen receptor (ER) expression vectors. In transient transfection experiments, IL-1-induced activation of the IL-6 promoter was efficiently inhibited by wt ER. However, estrogen receptors carrying mutations within or over-lapping with the DNA binding domain did not repress IL-6 promoter activity. A mutant receptor lacking the N-terminal transactivator function-1 but retaining the C-terminal transactivator function-2 also repressed activation of the IL-6 promoter. Our recent experiments indicate the requirement for both the nuclear factor (NF)-IL6 and the NF-kappa B sites in the IL-6 promoter for activation by IL-1. We now show that activation of the IL-6 promoter, elicited by a combination of NF-IL6 and the p65 subunit of NF-kappa B, can be inhibited by the wt receptor but not by a receptor containing a mutation in its DNA binding domain. Although a deletion within the DNA binding domain of ER abolished the repressor function of the receptor, a chimeric receptor ER-GR CAS1, in which the DNA binding domain of ER was swapped with the complementary region from the glucocorticoid receptor, retained the inhibitory effects on the IL-6 promoter. This was in contrast to the absolute dependence of ER on its own DNA binding domain for activation of typical estrogen response element-containing promoters, as reported previously by other investigators. Furthermore, the repression of the IL-6 promoter by a combination of ER and E2, unlike activation of estrogen response elements by the same combination, did not appear to be mediated via high affinity binding of the receptor to the promoter. In functional experiments, the transactivator function of ER was totally inhibited by overexpression of p65 and to a lesser extent by that of NF-IL6. These results indicate that ER may repress gene expression in the absence of high affinity DNA binding.