Vyas Keyur, Chaudhuri Sujan, Leaman Douglas W, Komar Anton A, Musiyenko Alla, Barik Sailen, Mazumder Barsanjit
Center for Gene Regulation in Health and Disease and Department of Biology, Cleveland State University, Cleveland, Ohio 44115, USA.
Mol Cell Biol. 2009 Jan;29(2):458-70. doi: 10.1128/MCB.00824-08. Epub 2008 Nov 10.
We previously showed that ribosomal protein L13a is required for translational silencing of gamma interferon (IFN-gamma)-induced ceruloplasmin (Cp) synthesis in monocytes. This silencing also requires the presence of the GAIT (IFN-gamma activated inhibitor of translation) element in the 3' untranslated region (UTR) of Cp mRNA. Considering that Cp is an inflammatory protein, we hypothesized that this mechanism may have evolved to silence a family of proinflammatory proteins, of which Cp is just one member. To identify the other mRNAs that are targets for this silencing, we performed a genome-wide analysis of the polysome-profiled mRNAs by using an Affymetrix GeneChip and an inflammation-responsive gene array. A cluster of mRNAs encoding different chemokines and their receptors was identified as common hits in the two approaches and validated by real-time PCR. In silico predicted GAIT hairpins in the 3' UTRs of the target mRNAs were confirmed as functional cis-acting elements for translational silencing by luciferase reporter assays. Consistent with Cp, the newly identified target mRNAs also required L13a for silencing. Our studies have identified a new inflammation-responsive posttranscriptional operon that can be regulated directly at the level of translation in IFN-gamma-activated monocytes. This regulation of a cohort of mRNAs encoding inflammatory proteins may be important to resolve inflammation.
我们先前表明，核糖体蛋白L13a是单核细胞中γ干扰素（IFN-γ）诱导的铜蓝蛋白（Cp）合成翻译沉默所必需的。这种沉默还需要Cp mRNA的3'非翻译区（UTR）中存在GAIT（IFN-γ激活的翻译抑制剂）元件。鉴于Cp是一种炎症蛋白，我们推测这种机制可能已经进化为使一类促炎蛋白沉默，而Cp只是其中一个成员。为了鉴定这种沉默的其他mRNA靶标，我们使用Affymetrix基因芯片和炎症反应基因阵列对多核糖体分析的mRNA进行了全基因组分析。编码不同趋化因子及其受体的一组mRNA在这两种方法中被鉴定为共同的命中靶点，并通过实时PCR进行了验证。通过荧光素酶报告基因测定，在靶mRNA的3'UTR中计算机预测的GAIT发夹被确认为翻译沉默的功能性顺式作用元件。与Cp一致，新鉴定的靶mRNA的沉默也需要L13a。我们的研究确定了一种新的炎症反应性转录后操纵子，它可以在IFN-γ激活的单核细胞的翻译水平上直接受到调控。这种对一组编码炎症蛋白的mRNA的调控可能对解决炎症很重要。
