Expression and Processing of a Small Nucleolar RNA from the Epstein-Barr Virus Genome
Expression and Processing of a Small Nucleolar RNA from the Epstein-Barr Virus Genome
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DOI：
10.1371/journal.ppat.1000547
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发表时间：
2009-08-01
期刊：
影响因子：
6.7
通讯作者：
Huettenhofer, Alexander
中科院分区：
文献类型：
--
作者：
Hutzinger, Roland;Feederle, Regina;Huettenhofer, Alexander
小核仁 RNA (snoRNA) 位于核仁（一个亚核区室）内，分别引导核糖体或剪接体 RNA 修饰。到目前为止，snoRNA 仅在真核和古细菌基因组中被发现，但在细菌中却明显缺失。通过筛选 B 淋巴细胞中 Epstein-Barr 病毒 (EBV) 诱导的非编码 RNA (ncRNA) 的表达，我们在此首次报告在病毒基因组中鉴定出 snoRNA 基因，称为 v-snoRNA1。该遗传元件显示了典型 C/D 盒 snoRNA 的所有标志序列基序，即 C/C'-以及 D/D'-盒。通过 EBV 感染细胞的原位杂交验证了 v-snoRNA1 的核仁定位。我们还证实了三种经典 snoRNA 蛋白 fibrillarin、Nop56 和 Nop58 与 v-snoRNA1 的结合。 v-snoRNA1 的 C 盒基序被证明对于病毒 snoRNA 的稳定性至关重要；它在病毒基因组中的选择性删除导致 EBV 感染的 B 细胞内 v-snoRNA1 表达水平完全下调。我们进一步提供证据表明 v-snoRNA1 可能作为 miRNA 样前体，被加工成 24 nt 大小的 RNA 种类，命名为 v-snoRNA1(24pp)。在编码病毒 DNA 聚合酶的 BALF5 mRNA 3'-UTR 内鉴定出 v-snoRNA1(24pp) 的潜在靶位点。发现 V-snoRNA1 在所有研究的 EBV 阳性细胞系中表达，包括类淋巴母细胞系 (LCL)。有趣的是，裂解周期的诱导使 v-snoRNA1 的表达水平显着上调高达 30 倍。通过计算方法，我们在恒河猴淋巴隐病毒基因组中鉴定出了 v-snoRNA1 同源物。这种进化保守性表明 v-snoRNA1 在 γ-疱疹病毒感染过程中发挥着重要作用。
Small nucleolar RNAs (snoRNAs) are localized within the nucleolus, a sub-nuclear compartment, in which they guide ribosomal or spliceosomal RNA modifications, respectively. Up until now, snoRNAs have only been identified in eukaryal and archaeal genomes, but are notably absent in bacteria. By screening B lymphocytes for expression of non-coding RNAs (ncRNAs) induced by the Epstein-Barr virus (EBV), we here report, for the first time, the identification of a snoRNA gene within a viral genome, designated as v-snoRNA1. This genetic element displays all hallmark sequence motifs of a canonical C/D box snoRNA, namely C/C'-as well as D/D'-boxes. The nucleolar localization of v-snoRNA1 was verified by in situ hybridisation of EBV-infected cells. We also confirmed binding of the three canonical snoRNA proteins, fibrillarin, Nop56 and Nop58, to v-snoRNA1. The C-box motif of v-snoRNA1 was shown to be crucial for the stability of the viral snoRNA; its selective deletion in the viral genome led to a complete down-regulation of v-snoRNA1 expression levels within EBV-infected B cells. We further provide evidence that v-snoRNA1 might serve as a miRNA-like precursor, which is processed into 24 nt sized RNA species, designated as v-snoRNA1(24pp). A potential target site of v-snoRNA1(24pp) was identified within the 3'-UTR of BALF5 mRNA which encodes the viral DNA polymerase. V-snoRNA1 was found to be expressed in all investigated EBV-positive cell lines, including lymphoblastoid cell lines (LCL). Interestingly, induction of the lytic cycle markedly up-regulated expression levels of v-snoRNA1 up to 30-fold. By a computational approach, we identified a v-snoRNA1 homolog in the rhesus lymphocryptovirus genome. This evolutionary conservation suggests an important role of v-snoRNA1 during gamma-herpesvirus infection.