Viral lncRNA upregulates multiple A+U-richViral lncRNA upregulates multiple A+U-rich transcripts to promote cell motility and viral dissemination transcripts to promote cell motility and viral dissemination

Long non-coding RNAs are frequently associated with broad modulation of gene expression and thus provide the cell with the ability to synchronize entire metabolic processes. We used transcriptomic and proteomic approaches to investigate whether the most abundant human cytomegalovirus-encoded lncRNA, RNA2.7, has this characteristic. By comparing RNA2.7 deletion mutants with wild-type virus, RNA2.7 was found to regulate a large number of cellular genes late in infection. Pathway analysis indicated that >100 RNA2.7-regulated cellular genes are associated with promoting cell movement, and ten of the most highly regulated were verified in further experiments. Morphological analysis and live cell tracking showed that RNA2.7 promotes the movement and detachment of infected cells late in infection, and plaque assays using sparse cell monolayers demonstrated that RNA2.7 promotes cell-to-cell dissemination and spread of virus. Bioinformatic analysis indicated that RNA2.7-upregulated mRNAs are relatively A+U-rich, which is a trait associated with transcript instability, and that they are also enriched in motifs associated with mRNA instability. Experiments involving transcriptional inhibition showed that transcripts from four RNA2.7-regulated cellular genes were longer-lived in the presence of RNA2.7. These findings demonstrate that RNA2.7 promotes cell movement and viral dissemination late in infection and indicate that this may be due to general stabilization of A+U-rich transcripts.

长链非编码RNA（long non-coding RNAs, lncRNA）通常与基因表达的广泛调控密切相关，进而赋予细胞同步调控整体代谢过程的能力。本研究采用转录组学与蛋白质组学分析方法，旨在探究丰度最高的人类巨细胞病毒（human cytomegalovirus）编码长链非编码RNA RNA2.7是否具备此类调控特性。通过对比RNA2.7缺失突变体与野生型病毒，研究发现RNA2.7可在感染后期调控大量宿主细胞基因。通路分析结果显示，受RNA2.7调控的宿主细胞基因中，逾100个与促进细胞运动相关，且其中10个受调控程度最高的基因在后续实验中得到了验证。形态学分析与活细胞追踪实验表明，RNA2.7可在感染后期促进受感染细胞的运动与脱离；利用稀疏细胞单层开展的空斑实验证实，RNA2.7可促进细胞间传播与病毒扩散。生物信息学分析显示，经RNA2.7上调的mRNA相对富含A+U序列，这一特征与转录本不稳定性存在关联，且此类mRNA同时富集了与转录本不稳定性相关的基序。转录抑制实验表明，在RNA2.7存在的条件下，4个受其调控的宿主细胞基因的转录本半衰期更长。上述研究结果证实，RNA2.7可在感染后期促进细胞运动与病毒传播，且提示这一作用可能通过稳定富含A+U的转录本这一通用机制实现。