Simar-Blanchet A E, Paul C, Mercier L, Le Cam A
INSERM U-376, hôpital Arnaud de Villeneuve, Montpellier, France.
Eur J Biochem. 1996 Mar 1;236(2):638-48. doi: 10.1111/j.1432-1033.1996.00638.x.
The rat serine protease inhibitor 2.3 gene (spi 2.3) is almost completely silent in normal animals and is transiently expressed during acute inflammation. It encodes a potential anti-elastase which is likely to play a major physiological role for the host defense. Two well-known inflammatory mediators, glucocorticoids and interleukin-6 (IL-6) activate the spi 2.3 promoter and increase steady-state levels of mRNA in cultured hepatocytes. GC activation is mediated by a single glucocorticoid-response element which seems to act autonomously. A unique array of four functional IL-6-response sites was identified in the spi 2.3 promoter. Three of them (C-II--IV) bear structural identity to the CCAAT/enhancer-binding-protein-binding site consensus sequence, whereas the fourth closely resembles the consensus kappa B nuclear factor recognition motif. The C-IV element, which is the most active, contains the motif 5'-CTGGGA and binds the IL-6-inducible acute-phase response factor present in liver nuclear extracts from inflamed rats. Both basal and IL-6-dependent activities of each individual cytokine-response element tested separately are strongly down regulated by a recently identified regulatory sequence, located in the 3' untranslated region of the spi 2.3 gene. However, this repressor element does not significantly affect overall IL-6-dependent spi 2.3 promoter activity. This suggests that, in the context of the active gene in vivo, all four IL-6-response sites, which are largely redundant, cooperate to overcome the strong repressive effect of the 3' untranslated region silencer and are needed to bring about a maximal IL-6 response. These data reveal a novel type of regulation of an acute-phase gene involving different classes of IL-6-response elements controlled by a repressor and acting in conjunction with a glucocorticoid-response element.
大鼠丝氨酸蛋白酶抑制剂2.3基因（spi 2.3）在正常动物中几乎完全不表达，在急性炎症期间短暂表达。它编码一种潜在的抗弹性蛋白酶，可能在宿主防御中发挥主要生理作用。两种著名的炎症介质，糖皮质激素和白细胞介素-6（IL-6）可激活spi 2.3启动子并增加培养肝细胞中mRNA的稳态水平。糖皮质激素的激活由单个糖皮质激素反应元件介导，该元件似乎自主发挥作用。在spi 2.3启动子中鉴定出一组独特的四个功能性IL-6反应位点。其中三个（C-II--IV）与CCAAT/增强子结合蛋白结合位点共有序列具有结构同一性，而第四个与κB核因子识别基序共有序列非常相似。最活跃的C-IV元件包含基序5'-CTGGGA，并结合来自炎症大鼠肝脏核提取物中的IL-6诱导急性期反应因子。单独测试的每个细胞因子反应元件的基础活性和IL-6依赖性活性均受到位于spi 2.3基因3'非翻译区的最近鉴定的调控序列的强烈下调。然而，该阻遏元件不会显著影响整体IL-6依赖性spi 2.3启动子活性。这表明，在体内活性基因的背景下，所有四个IL-6反应位点在很大程度上是冗余的，它们协同作用以克服3'非翻译区沉默子的强烈抑制作用，并且是实现最大IL-6反应所必需的。这些数据揭示了一种新型急性期基因调控方式，涉及由阻遏物控制并与糖皮质激素反应元件协同作用的不同类别的IL-6反应元件。
