BACKGROUND Human enterovirus 71 (EV-A71) is a non-enveloped virus that has a single stranded positive sense RNA genome. In a previous study, we showed that miR-876-5p upregulation was observed in the serum of patients with severe EV-A71 infection. Micro-876-5p (miR-876-5p) is a circulating miRNA that can be identified to modulate EV-A71 infections through both in vitro and in vivo studies. However, the regulatory mechanisms that involve miR-876-5p in the EV-A71 infection cycle remain unclear. METHODS We demonstrated that miR-876-5p facilitated EV-A71 replication and expression by overexpression and knocking-down of miR-876-5p through the transfection of miR-876-5p plasmid and miR-876-5p inhibitor. Although miR-876-5p suppressed CREB5 expression, luciferase reporter assay confirmed this. We also evaluated the role of miR-876-5p in the EV-A71 infection cycle by CREB5 mediated by transfection with an anti-miR-876-5P inhibitor or in combination with an si-CREB5 plasmid. RESULTS MicroR-876-5p was upregulated in EV-A71-infected neuroblastoma cells. Overexpression of miR-876-5p or knockdown of cyclic-AMP responsive element binding protein 5 (CREB5) promoted EV-A71 replication. The downregulation of miR-876-5p inhibited the accumulation of viral RNA and the production of viral proteins. Interestingly, CREB5 overexpression also suppressed EV-A71 replication. Our in vitro studies reveal that miR-876-5p directly targets CREB5. Finally, downregulation of CREB5 protein abated the inhibitory effect of anti-miR-876-5p and induced inhibitory effect of EV-A71 replication. CONCLUSIONS Our results suggest that intracellular miR-876-5p promotes EV-A71 replication indirectly by targeting the host CREB5 protein.

中文翻译：

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MicroRNA 876-5p通过下调宿主抗病毒因子来调节EV-A71复制。

背景技术人肠病毒71（EV-A71）是具有单链正向RNA基因组的非包膜病毒。在先前的研究中，我们显示在患有严重EV-A71感染的患者血清中观察到miR-876-5p上调。Micro-876-5p（miR-876-5p）是一种循环miRNA，可以通过体外和体内研究鉴定为调节EV-A71感染。但是，尚不清楚在EV-A71感染周期中涉及miR-876-5p的调控机制。方法我们证明了miR-876-5p通过miR-876-5p质粒和miR-876-5p抑制剂的转染，通过过表达和敲低miR-876-5p来促进EV-A71复制和表达。尽管miR-876-5p抑制了CREB5的表达，但荧光素酶报告基因检测证实了这一点。我们还评估了miR-876-5p在CREB5介导的抗miR-876-5P抑制剂或与si-CREB5质粒组合转染介导的CREB5对EV-A71感染周期中的作用。结果MicroR-876-5p在EV-A71感染的神经母细胞瘤细胞中表达上调。miR-876-5p的过表达或环-AMP响应元件结合蛋白5（CREB5）的敲低促进了EV-A71复制。miR-876-5p的下调抑制了病毒RNA的积累和病毒蛋白的产生。有趣的是，CREB5过表达也抑制了EV-A71复制。我们的体外研究表明，miR-876-5p直接靶向CREB5。最后，CREB5蛋白的下调减轻了抗miR-876-5p的抑制作用，并诱导了EV-A71复制的抑制作用。