Interleukin-1β induced Stress Granules Sequester COX-2 mRNA and Regulates its Stability and Translation in Human OA Chondrocytes.
Interleukin-1β induced Stress Granules Sequester COX-2 mRNA and Regulates its Stability and Translation in Human OA Chondrocytes.
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DOI：
10.1038/srep27611
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发表时间：
2016-06-08
影响因子：
4.6
通讯作者：
Haqqi TM
中科院分区：
文献类型：
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作者：
Ansari MY;Haqqi TM
IL-1β刺激OA软骨细胞后，立即观察到环氧化酶-2（考克斯-2）mRNA表达增强，但蛋白质合成明显延迟。在此，我们研究了应激颗粒（SGs），即调节mRNA翻译的核糖核蛋白复合物在IL-1β刺激的OA软骨细胞中考克斯-2 mRNA延迟翻译中的作用。用IL-1β刺激人软骨细胞激活了应激反应基因和eIF 2 α的磷酸化，从而触发了SGs的组装。采用SG标记物和考克斯-2蛋白的联合免疫荧光染色、RNA荧光原位杂交和RNA免疫沉淀，发现考克斯-2 mRNA被隔离在IL-1β刺激的OA软骨细胞的SG中。在SGs持续期间未观察到考克斯-2蛋白表达增加，但在SGs清除后观察到考克斯-2蛋白表达增强。抑制SGs清除阻断了考克斯-2 mRNA的翻译，而通过TIA-1耗竭阻断SGs的组装导致考克斯-2和PGE 2的快速和增加的产生。我们的研究结果首次显示，在病理条件下，人OA软骨细胞中SGs的组装和考克斯-2 mRNA的隔离。SG对考克斯-2 mRNA翻译的转录后调节表明其在IL-1β介导的分解代谢反应中的作用，这可能是OA的治疗靶点。
Enhanced and immediate expression of cyclooxygenase-2 (COX-2) mRNA is observed in IL-1β-stimulated OA chondrocytes but the synthesis of protein found significantly delayed. Here we investigated the role of stress granules (SGs), ribonucleoprotein complexes that regulate mRNA translation, in the delayed translation of COX-2 mRNAs in IL-1β-stimulated OA chondrocytes. Stimulation of human chondrocytes with IL-1β activated the stress response genes and the phosphorylation of eIF2α that triggered the assembly of SGs. Using combined immunofluorescence staining of SGs markers and COX-2 protein, RNA fluorescence in situ hybridization and RNA immunoprecipitation, the COX-2 mRNAs were found sequestered in SGs in IL-1β-stimulated OA chondrocytes. No increase in COX-2 protein expression was observed during the persistence of SGs but enhanced expression of COX-2 protein was noted upon clearance of the SGs. Inhibition of SGs clearance blocked COX-2 mRNA translation whereas blocking the assembly of SGs by TIA-1 depletion resulted in rapid and increased production of COX-2 and PGE2. Our findings show for the first time assembly of SGs and sequestration of COX-2 mRNAs in human OA chondrocytes under pathological conditions. Post-transcriptional regulation of COX-2 mRNAs translation by SGs indicates a role in IL-1β-mediated catabolic response that could be therapeutically targeted in OA.