Tristetraprolin down-regulates IL-2 gene expression through AU-rich element-mediated mRNA decay
Tristetraprolin down-regulates IL-2 gene expression through AU-rich element-mediated mRNA decay
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DOI：
10.4049/jimmunol.174.2.953
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发表时间：
2005-01-15
影响因子：
4.4
通讯作者：
Bohjanen, PR
中科院分区：
文献类型：
--
作者：
Ogilvie, RL;Abelson, M;Bohjanen, PR
IL-2基因表达在mRNA降解水平的转录后调节由在3 '非翻译区发现的富含AU的元件（.ARE）介导。我们假设ARE结合蛋白tristetraprolin（TTP）通过与IL-2 ARE相互作用并靶向转录物进行衰变来调节T淋巴细胞IL-2 mRNA的衰变。在HeLa细胞中表达的rTTP蛋白在凝胶迁移分析中以高亲和力特异性结合IL-2 ARE。在原代人T淋巴细胞中，TCR和CD 28辅助受体刺激诱导TTP mRNA和蛋白表达。使用凝胶迁移试验，我们确定了细胞质RNA结合活性，诱导TCR和CD 28辅助受体刺激和结合特异性的IL-2 ARE序列。使用抗TTP抗体，我们通过超位移表明这种诱导活性包含TTP。我们还表明，将IL-2 ARE序列插入到β-珠蛋白报告基因构建体的3 '非翻译区中，可使β-珠蛋白报告基因产生TTP依赖性mRNA去稳定化。为了确定TTP是否也在体内调节IL-2基因表达，我们检测了野生型和TTP敲除小鼠原代细胞中IL-2的表达。与野生型相比。TCR和CD 28活化的脾细胞和TTP敲除小鼠的T细胞过表达IL-2 mRNA和蛋白。Also. IL-2 mRNA表达量较多。与野生型小鼠相比，在TTP敲除小鼠的活化脾细胞中稳定。综上所述，这些数据表明TTP通过ARE介导的mRNA降解下调IL-2基因表达。
Posttranscriptional regulation of IL-2 gene expression at the level of mRNA decay is mediated by an AU-rich element (.ARE,) found in the 3'-untranslated region. We hypothesized that the ARE-binding protein tristetraprolin (TTP) regulates T lymphocyte IL-2 mRNA decay by interacting with the IL-2 ARE and targeting the transcript for decay. rTTP protein expressed in HeLa cells bound specifically to the IL-2 ARE with high affinity in a gel shift assay. In primary human T lymphocytes, TTP mRNA and protein expression were induced by TCR and CD28 coreceptor stimulation. Using a gel shift assay, we identified a cytoplasmic RNA-binding activity that was induced by TCR and CD28 coreceptor stimulation and bound specifically to the IL-2 ARE sequence. Using anti-TTP Abs, we showed by supershift that this inducible activity contained TTP. We also showed that insertion of the IL-2 ARE sequence into the 3'-untranslated region of a P-globin reporter construct conferred TTP-dependent mRNA destabilization on the beta-globin reporter. To determine whether TTP also regulates IL-2 gene expression in vivo, we examined IL-2 expression in primary cells from wild-type and TTP knockout mice. Compared with their wild-type counterparts. TCR- and CD28-activated splenocytes and T cells from TTP knockout mice overexpressed IL-2 mRNA and protein. Also. IL-2 mRNA was more. stable in activated splenocytes from TTP knockout mice compared with wild-type mice.-Taken together, these data suggest that TTP functions to down-regulate IL-2 gene expression through ARE-mediated mRNA decay.