Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
PLoS One. 2011 Jan 20;6(1):e16224. doi: 10.1371/journal.pone.0016224.
Seventeen miRNAs encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) have been identified and their functions have begun to be characterized. Among these miRNAs, we report here that miR-K12-7 directly targets the replication and transcription activator (RTA) encoded by open reading frame 50. We found that miR-K12-7 targeted the RTA 3' untranslated region (RTA3'UTR) in a seed sequence-dependent manner. miR-K12-7-5p derived from miR-K12-7 mediates the inhibition of RTA expression, and the mutation of the seed match site totally abrogated the inhibitory effect of miR-K12-7 on RTA3'UTR. The inhibition of RTA expression by miR-K12-7 was further confirmed in the latently KSHV-infected 293/Bac36 cell line through transient transfection of miR-K12-7 expression plasmid or specific inhibitor of miR-K12-7-5p, respectively. The transient transfection of miR-K12-7 into 293/Bac36 cells reduced RTA expression and the expression of the downstream early genes regulated by RTA, and also the production of progeny virus was significantly reduced after treatment with chemical inducers. Our study revealed that another miRNA, miR-K12-7-5p, targets the viral immediate early gene RTA and that this miRNA contributes to the maintenance of viral latency.
卡波西肉瘤相关疱疹病毒 (KSHV) 编码的 17 个 miRNA 已被鉴定，其功能也开始被表征。在这些 miRNA 中，我们在此报告 miR-K12-7 可直接靶向开放阅读框 50 编码的复制和转录激活物 (RTA)。我们发现 miR-K12-7 以种子序列依赖性方式靶向 RTA 的 3'非翻译区 (RTA3'UTR)。源自 miR-K12-7 的 miR-K12-7-5p 介导 RTA 表达的抑制，而种子匹配位点的突变完全消除了 miR-K12-7 对 RTA3'UTR 的抑制作用。通过瞬时转染 miR-K12-7 表达质粒或 miR-K12-7-5p 的特异性抑制剂，分别在潜伏感染 KSHV 的 293/Bac36 细胞系中进一步证实了 miR-K12-7 对 RTA 表达的抑制作用。将 miR-K12-7 瞬时转染到 293/Bac36 细胞中，降低了 RTA 表达及其下游由 RTA 调节的早期基因的表达，并且在用化学诱导剂处理后，子代病毒的产生也显著减少。我们的研究表明，另一种 miRNA，miR-K12-7-5p，靶向病毒的即刻早期基因 RTA，并且这种 miRNA 有助于病毒潜伏的维持。
