Genomewide Mapping and Screening of Kaposi's Sarcoma-Associated Herpesvirus (KSHV) 3′ Untranslated Regions Identify Bicistronic and Polycistronic Viral Transcripts as Frequent Targets of KSHV MicroRNAs
Genomewide Mapping and Screening of Kaposi's Sarcoma-Associated Herpesvirus (KSHV) 3′ Untranslated Regions Identify Bicistronic and Polycistronic Viral Transcripts as Frequent Targets of KSHV MicroRNAs
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DOI：
10.1128/jvi.02689-13
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发表时间：
2014-01-01
影响因子：
5.4
通讯作者：
Gao, Shou-Jiang
中科院分区：
文献类型：
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作者：
Bai, Zhiqiang;Huang, Yufei;Gao, Shou-Jiang
卡波西肉瘤相关疱疹病毒（KSHV）编码超过90个基因和25个microrna （mirna）。KSHV的生命周期受到严格调控，以确保宿主的持续感染。特别是，mirna主要通过结合靶转录物的3‘非翻译区（3’ utrs）发挥作用，最近成为KSHV生命周期的关键调节因子。尽管使用RNA交联免疫沉淀方法的研究已经确定了许多KSHV mirna的靶标，但由于大多数KSHV 3' utr尚未被表征，因此这些靶标中很少是病毒起源的。因此，KSHV mirna靶向的病毒基因的范围仍然难以捉摸。在这里，我们报道了74个KSHV基因的3' utr的定位，以及KSHV mirna对这些3' utr介导的基因表达的控制作用。这一分析揭示了KSHV基因新的双反子和多反子转录本。由于5‘远端开放阅读框（orf）， KSHV双反子转录本或多反子转录本的3’ utr明显比KSHV单反子转录本长。此外，对3'UTR报告子的筛选已经确定了28个KSHV mirna的潜在新靶标，其中11个（39%）是双反子或多反子转录本。报告突变表明，miR-K3通过ORF33编码区的两个结合位点特异性靶向ORF31-33裂解位点的转录本，而miR-K10a-3p和miR-K10b-3p及其变体通过5'-远端orf和基因间区的不同结合位点靶向潜伏位点的ORF71-73转录本。我们的研究结果表明，KSHV miRNAs经常靶向双反子或多反子转录本的5'-远端编码区，并突出了KSHV miRNAs在调节基因表达和生命周期方面的独特特征。
Kaposi's sarcoma-associated herpesvirus (KSHV) encodes over 90 genes and 25 microRNAs (miRNAs). The KSHV life cycle is tightly regulated to ensure persistent infection in the host. In particular, miRNAs, which primarily exert their effects by binding to the 3' untranslated regions (3'UTRs) of target transcripts, have recently emerged as key regulators of KSHV life cycle. Although studies with RNA cross-linking immunoprecipitation approach have identified numerous targets of KSHV miRNAs, few of these targets are of viral origin because most KSHV 3'UTRs have not been characterized. Thus, the extents of viral genes targeted by KSHV miRNAs remain elusive. Here, we report the mapping of the 3'UTRs of 74 KSHV genes and the effects of KSHV miRNAs on the control of these 3'UTR-mediated gene expressions. This analysis reveals new bicistronic and polycistronic transcripts of KSHV genes. Due to the 5'-distal open reading frames (ORFs), KSHV bicistronic or polycistronic transcripts have significantly longer 3'UTRs than do KSHV monocistronic transcripts. Furthermore, screening of the 3'UTR reporters has identified 28 potential new targets of KSHV miRNAs, of which 11 (39%) are bicistronic or polycistronic transcripts. Reporter mutagenesis demonstrates that miR-K3 specifically targets ORF31-33 transcripts at the lytic locus via two binding sites in the ORF33 coding region, whereas miR-K10a-3p and miR-K10b-3p and their variants target ORF71-73 transcripts at the latent locus through distinct binding sites in both 5'-distal ORFs and intergenic regions. Our results indicate that KSHV miRNAs frequently target the 5'-distal coding regions of bicistronic or polycistronic transcripts and highlight the unique features of KSHV miRNAs in regulating gene expression and life cycle.