Investigation of a translational control mechanism activated by interleukin 1

促炎细胞因子IL-1激活转录后机制，促进参与免疫和炎症反应的蛋白质的表达。在第一个资助期获得的信息表明，IL-1通过对抗翻译沉默机制增加了两组不同mRNAs的翻译。其中一组以IL-6和IL-1α的mRNAs为代表，翻译上被KSRP沉默，KSRP是一种与这些mRNAs中富含AU的元件(ARE)相互作用的蛋白质。第二类，以IkappaBzeta和MCPIP1的mRNAs为代表，独立于KSRP和ARE而沉默。我们最近的观察表明，MCPIP1蛋白(AUTO)通过与这些mRNAs相互作用来调节自己和IkappaBzeta的mRNA的翻译。因此，MCPIP1最近被描述为炎症基因表达的重要负反馈调节因子，是IL-1调节靶基因非ARE组的候选分子。重要的是，在不同的细胞类型以及细菌脂多糖和IL-17的反应中都获得了这种调控的证据。为了阐明这种翻译调控的分子机制，我们计划在IkappaBzeta mRNA的翻译沉默元件的背景下分析MCPIP1的功能。主要目的是获得翻译沉默所需的MCPIP1的结构特征(包括其核糖核酸酶活性的作用)、MCPIP1与其他蛋白质的相互作用、IL-1对MCPIP1功能的调节以及MCPIP1靶向mRNAs的谱。所获得的信息将有助于填补我们在炎症过程中转录后调控基因表达方面的知识空白。

The pro-inflammatory cytokine IL-1 activates post-transcriptional mechanisms that contribute to the expression of proteins involved in immune and inflammatory reactions. Information obtained in the first funding period indicates that IL-1 increases translation of two distinct groups of mRNAs by counteracting translational silencing mechanisms. One group, represented by mRNAs of IL-6 and IL-1alpha itself, is translationally silenced by KSRP, a protein that interacts with AU-rich elements (AREs) in these mRNAs. The second group, represented by mRNAs of IkappaBzeta and MCPIP1, is silenced independently of KSRP and AREs.Our recent observations suggest that MCPIP1 protein (auto)regulates translation of its own mRNA and that of IkappaBzeta through interaction with these mRNAs. Thus MCPIP1, recently described as an important negative feedback regulator of inflammatory gene expression, is a candidate for regulating the non-ARE group of target mRNAs by IL-1. Importantly, evidence for this kind of regulation was obtained in different cell types and also in response to bacterial lipopolysaccharide and IL-17.To elucidate the molecular mechanism of this kind of translational control, we plan to analyse MCPIP1 function in the context of the translational silencing element of IkappaBzeta mRNA. Key objectives are to obtain information on structural features of MCPIP1 required for translational silencing (including the role of its RNase activity), the interaction of MCPIP1 with other proteins, the modulation of MCPIP1 function by IL-1, and the spectrum of target mRNAs of MCPIP1.The information gained should contribute to closing a gap in our knowledge on post-transcriptional control of gene expression during inflammation.