Fragile X-related protein FXR1P regulates proinflammatory cytokine tumor necrosis factor expression at the post-transcriptional level
Fragile X-related protein FXR1P regulates proinflammatory cytokine tumor necrosis factor expression at the post-transcriptional level
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DOI：
10.1074/jbc.m401988200
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发表时间：
2005-02-18
影响因子：
4.8
通讯作者：
Radzioch, D
中科院分区：
文献类型：
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作者：
Garnon, J;Lachance, C;Radzioch, D
肿瘤坏死因子(TNF)是由富含AU的元件(ARE)转录后调控的，位于其mRNA的3‘非翻译区。这种调节调节翻译效率和mRNA的稳定性。利用含有肿瘤坏死因子ARE序列的cRNA探针，筛选了巨噬细胞蛋白表达文库，并鉴定了FXR1P。我们从FXR1基因敲除小鼠产生的巨噬细胞在激活后比野生型巨噬细胞产生更多的肿瘤坏死因子蛋白。受ARE序列调控的其他几种蛋白质的表达也受到FXR1P缺乏的影响。在FXR1P基因缺失的巨噬细胞中，表达绿色荧光蛋白(GFP)的GFP-ARE报告基因在肿瘤坏死因子基因3‘非翻译区的表达增强。最后，我们发现，FXR1P的消融导致了肿瘤坏死因子mRNA与多聚核糖体的结合显著增强，表明了FXR1P在转录后调控肿瘤坏死因子表达中的重要作用。我们的数据表明，FXR1P在脂多糖诱导的巨噬细胞活化过程中释放了这种抑制。最后，重组FXR1P对敲除的巨噬细胞的补充导致了肿瘤坏死因子蛋白产量的减少，支持了我们的发现，即FXR1P是一种肿瘤坏死因子翻译的抑制因子。
Tumor necrosis factor (TNF) is regulated post-transcriptionally by the AU-rich element (ARE) within the 3'-untranslated region of its mRNA. This regulation modulates translational efficacy and mRNA stability. By using a cRNA probe containing the TNF ARE sequence, we screened a macrophage protein expression library and identified FXR1P. Macrophages that we generated from FXR1 knock-out mice had enhanced TNF protein production compared with wild type macrophages following activation. Expression of several other proteins that are regulated by ARE sequences was also affected by FXR1P deficiency. A GFP-ARE reporter that has green fluorescent protein (GFP) expression under control of the 3'-untranslated region of TNF mRNA had enhanced expression in transfected macrophages deficient in FXR1P. Finally, we found that the ablation of FXR1P led to a dramatically enhanced association of the TNF mRNA with polyribosomes demonstrating the important role of FXR1P in the post-transcriptional regulation of TNF expression. Our data suggest that release of this repression by FXR1P occurs during lipopolysaccharideinduced macrophage activation. Finally, complementation of the knock-out macrophages with recombinant FXR1P resulted in decreased TNF protein production, supporting our findings that FXR1P operates as a repressor of TNF translation.