Translational regulation of specific mRNAs controls feedback inhibition and survival during macrophage activation.
Translational regulation of specific mRNAs controls feedback inhibition and survival during macrophage activation.
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DOI：
10.1371/journal.pgen.1004368
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发表时间：
2014-06
期刊：
影响因子：
4.5
通讯作者：
Stoecklin G
中科院分区：
文献类型：
--
作者：
Schott J;Reitter S;Philipp J;Haneke K;Schäfer H;Stoecklin G
为了快速诱导和有效解决炎症反应，免疫系统细胞中的基因表达在转录和转录后水平受到严格调控。 mRNA 翻译的控制已成为蛋白质水平的重要决定因素，但其在巨噬细胞激活中的作用尚不清楚。我们通过脂多糖（LPS）刺激的小鼠巨噬细胞的多核糖体分离，系统地分析了翻译调控对巨噬细胞反应早期阶段的贡献。通过微阵列分析鉴定了在巨噬细胞激活过程中翻译受到特异性调节的单个 mRNA。 LPS 刺激 1 小时引起许多炎症反应反馈抑制剂的翻译激活，包括 NF-κB 抑制剂（Nfkbid、Nfkbiz、Nr4a1、Ier3）、p38 MAPK 拮抗剂（Dusp1）和细胞因子表达的转录后抑制因子（Zfp36 和 Zc3h12a）。我们的分析表明，它们的翻译在静息状态下受到抑制，而在激活的巨噬细胞中则解除抑制。通过 RNASeq 以高时间分辨率对 mRNA 水平进行定量，使我们能够定义具有不同表达模式的组。因此，我们能够区分翻译受到主动调节的 mRNA 和多核糖体变化是由于 mRNA 水平变化引起的 mRNA。翻译的主动上调与富含 AU 元素 (ARE) 的较高含量相关。以 Ier3 mRNA 为例，我们发现静息细胞中的抑制以及刺激后的去抑制取决于 ARE。来自 Ier3 敲除小鼠的骨髓来源的巨噬细胞在激活后表现出存活率降低，表明 IER3 诱导可保护巨噬细胞免受 LPS 诱导的细胞死亡。综上所述，我们的分析表明，巨噬细胞激活过程中的翻译控制对于细胞存活以及促进炎症消退的抗炎反馈抑制剂的表达非常重要。当巨噬细胞遇到病原体时，它们会通过分泌细胞因子 TNF 等促炎因子引发炎症。由于这些因子的长期或过度释放对生物体有害，因此需要严格控制并适时停止它们的产生。为了确保快速但短暂的炎症反应，基因表达在多个水平上受到调节，包括 mRNA 的转录、稳定性和翻译。虽然转录控制和 mRNA 稳定性已被广泛研究，但人们对巨噬细胞的翻译调控知之甚少。在这项研究中，我们测量了小鼠巨噬细胞中表达的所有 mRNA 的翻译。在用细菌细胞壁成分脂多糖激活巨噬细胞后，我们发现许多对于抑制炎症反应很重要的反馈抑制剂都被翻译上调。这些 mRNA 的翻译在静息细胞中受到抑制，并在刺激后解除抑制。与反馈抑制剂相反，大多数细胞因子主要受 mRNA 丰度变化的调节。此外，我们还可以证明反馈抑制剂之一 IER3 可保护巨噬细胞在激活过程中免于细胞死亡。因此，翻译水平的调节对于负反馈环的诱导和细胞存活很重要。
For a rapid induction and efficient resolution of the inflammatory response, gene expression in cells of the immune system is tightly regulated at the transcriptional and post-transcriptional level. The control of mRNA translation has emerged as an important determinant of protein levels, yet its role in macrophage activation is not well understood. We systematically analyzed the contribution of translational regulation to the early phase of the macrophage response by polysome fractionation from mouse macrophages stimulated with lipopolysaccharide (LPS). Individual mRNAs whose translation is specifically regulated during macrophage activation were identified by microarray analysis. Stimulation with LPS for 1 h caused translational activation of many feedback inhibitors of the inflammatory response including NF-κB inhibitors (Nfkbid, Nfkbiz, Nr4a1, Ier3), a p38 MAPK antagonist (Dusp1) and post-transcriptional suppressors of cytokine expression (Zfp36 and Zc3h12a). Our analysis showed that their translation is repressed in resting and de-repressed in activated macrophages. Quantification of mRNA levels at a high temporal resolution by RNASeq allowed us to define groups with different expression patterns. Thereby, we were able to distinguish mRNAs whose translation is actively regulated from mRNAs whose polysomal shifts are due to changes in mRNA levels. Active up-regulation of translation was associated with a higher content in AU-rich elements (AREs). For one example, Ier3 mRNA, we show that repression in resting cells as well as de-repression after stimulation depends on the ARE. Bone-marrow derived macrophages from Ier3 knockout mice showed reduced survival upon activation, indicating that IER3 induction protects macrophages from LPS-induced cell death. Taken together, our analysis reveals that translational control during macrophage activation is important for cellular survival as well as the expression of anti-inflammatory feedback inhibitors that promote the resolution of inflammation. When macrophages encounter pathogens, they initiate inflammation by secreting pro-inflammatory factors such as the cytokine TNF. Because a prolonged or overshooting release of these factors is harmful for the organism, their production needs to be tightly controlled and shut off in due time. To ensure a rapid but transient inflammatory response, gene expression is regulated at multiple levels, including transcription, stability and translation of mRNAs. While control of transcription and mRNA stability has been studied extensively, little is known about translational regulation in macrophages. In this study, we measured the translation of all mRNAs expressed in mouse macrophages. Upon activation of macrophages with the bacterial cell wall component lipopolysaccharide, we found that many feedback inhibitors, which are important for dampening the inflammatory response, are translationally up-regulated. Translation of these mRNAs is repressed in resting cells and de-repressed after stimulation. In contrast to feedback inhibitors, most cytokines are primarily regulated by changes in mRNA abundance. Furthermore, we could show that one of the feedback inhibitors, IER3, protects macrophages from cell death during activation. Therefore, regulation at the level of translation is important for the induction of negative feedback loops and cellular survival.
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影响因子：
32.4
作者：
Kontoyiannis, D;Pasparakis, M;Kollias, G
通讯作者：
Kollias, G
影响因子：
12.3
作者：
Gentleman RC;Carey VJ;Bates DM;Bolstad B;Dettling M;Dudoit S;Ellis B;Gautier L;Ge Y;Gentry J;Hornik K;Hothorn T;Huber W;Iacus S;Irizarry R;Leisch F;Li C;Maechler M;Rossini AJ;Sawitzki G;Smith C;Smyth G;Tierney L;Yang JY;Zhang J
通讯作者：
Zhang J
DOI：
10.1084/jem.20051753
发表时间：
2006-01-23
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Hammer M;Mages J;Dietrich H;Servatius A;Howells N;Cato AC;Lang R
通讯作者：
Lang R
影响因子：
4.8
作者：
Garnon, J;Lachance, C;Radzioch, D
通讯作者：
Radzioch, D
DOI：
10.1159/000289196
发表时间：
2010
期刊：
Current directions in autoimmunity
影响因子：
--
作者：
Falvo JV;Tsytsykova AV;Goldfeld AE
通讯作者：
Goldfeld AE