Post-transcriptional control of cyclooxygenase-2 gene expression -: The role of the 3′-untranslated region
Post-transcriptional control of cyclooxygenase-2 gene expression -: The role of the 3′-untranslated region
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DOI：
10.1074/jbc.275.16.11750
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发表时间：
2000-04-21
影响因子：
4.8
通讯作者：
Prescott, SM
中科院分区：
文献类型：
--
作者：
Dixon, DA;Kaplan, CD;Prescott, SM
环氧合酶（考克斯）-2酶负责炎症状态下前列腺素形成的增加，并且是非甾体抗炎药的主要靶点。通常情况下，考克斯-2的表达受到严格的调控，然而，组成性过表达在结肠癌的发生中起重要作用。为了理解控制考克斯-2表达的机制，我们检测了考克斯-2 mRNA的3 '非翻译区调节转录后事件的能力。当与报告基因融合时，3 '-非翻译区介导快速mRNA衰减（t（1/2）= 30 min），这与用放线菌素D或地塞米松处理的血清诱导的成纤维细胞中的内源性考克斯-2 mRNA周转相当。缺失分析表明，一个保守的116个核苷酸的AU丰富的序列元件（ARE）介导的mRNA降解。在瞬时转染细胞中，该区域抑制蛋白质合成约3倍。然而，这种抑制并没有通过mRNA稳定性的变化发生，因为mRNA半衰期和稳态mRNA水平不变。RNA迁移率变动分析表明，一个复杂的细胞质蛋白，结合特异性的ARE，和UV交联研究确定的蛋白质范围从90至35 kDa。分级的胞质溶胶显示微分协会ARE结合蛋白的多核糖体和S130馏分。我们认为，这些因素的影响表达在转录后的步骤，如果失调，可能会增加考克斯-2蛋白在结肠癌中检测。
The cyclooxygenase (COX)-2 enzyme is responsible for increased prostaglandin formation in inflammatory states and is the major target of nonsteroidal anti-inflammatory drugs. Normally COX-2 expression is tightly regulated, however, constitutive overexpression plays a hey role in colon carcinogenesis. To understand the mechanisms controlling COX-2 expression, we examined the ability of the 3'-untranslated region of the COX-2 mRNA to regulate post-transcriptional events. When fused to a reporter gene, the 3'-untranslated region mediated rapid mRNA decay (t(1/2) = 30 min), which was comparable to endogenous COX-2 mRNA turnover in serum-induced fibroblasts treated with actinomycin D or dexamethasone. Deletion analysis demonstrated that a conserved 116-nucleotide AU-rich sequence element (ARE) mediated mRNA degradation. In transiently transfected cells, this region inhibited protein synthesis approximately 3-fold. However, this inhibition did not occur through changes in mRNA stability since mRNA half-life and steady-state mRNA levels were unchanged. RNA mobility shift assays demonstrated a complex of cytoplasmic proteins that bound specifically to the ARE, and UV cross-linking studies identified proteins ranging from 90 to 35 kDa. Fractionation of the cytosol showed differential association of ARE-binding proteins to polysomes and S130 fractions. We propose that these factors influence expression at a post-transcriptional step and, if dysregulated, may increase COX-2 protein as detected in colon cancer.