A genome-wide RNAi screen reveals that mRNA decapping restricts bunyaviral replication by limiting the pools of Dcp2-accessible targets for cap-snatching
A genome-wide RNAi screen reveals that mRNA decapping restricts bunyaviral replication by limiting the pools of Dcp2-accessible targets for cap-snatching
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DOI：
10.1101/gad.215384.113
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发表时间：
2013-07-01
影响因子：
10.5
通讯作者：
Cherry, Sara
中科院分区：
文献类型：
--
作者：
Hopkins, Kaycie C.;McLane, Laura M.;Cherry, Sara
布尼亚病毒是一组新兴的医学重要病毒，其中许多是从昆虫传播到哺乳动物。为了确定影响感染的宿主因素，我们在果蝇中进行了全基因组RNAi筛选，并确定了131个影响蚊子传播的布尼亚病毒裂谷热病毒（RVFV）感染的基因。Dcp 2是mRNA去帽机制的催化成分，DDX 6和LSM 7是两种去帽激活剂，它们在昆虫细胞和成虫中对不同的布尼亚病毒具有抗病毒作用。布尼亚病毒通过“夺帽”不明确的宿主mRNA的5'端来给它们的mRNA加帽。我们发现RVFV cap-snatches Dcp 2靶向mRNA的5'端，包括细胞周期相关基因。Dcp 2的缺失允许增加病毒转录而不影响病毒mRNA稳定性，而Dcp 2的异位表达阻碍病毒转录。此外，在S期晚期/G2期早期阻滞细胞导致Dcp 2 mRNA靶标增加和RVFV复制增加。因此，RVFV竞争Dcp 2可接近的mRNA库，其是动态调节的，并且可以呈现病毒复制的瓶颈。
Bunyaviruses are an emerging group of medically important viruses, many of which are transmitted from insects to mammals. To identify host factors that impact infection, we performed a genome-wide RNAi screen in Drosophila and identified 131 genes that impacted infection of the mosquito-transmitted bunyavirus Rift Valley fever virus (RVFV). Dcp2, the catalytic component of the mRNA decapping machinery, and two decapping activators, DDX6 and LSM7, were antiviral against disparate bunyaviruses in both insect cells and adult flies. Bunyaviruses 5' cap their mRNAs by "cap-snatching'' the 5' ends of poorly defined host mRNAs. We found that RVFV cap-snatches the 5' ends of Dcp2 targeted mRNAs, including cell cycle-related genes. Loss of Dcp2 allows increased viral transcription without impacting viral mRNA stability, while ectopic expression of Dcp2 impedes viral transcription. Furthermore, arresting cells in late S/early G2 led to increased Dcp2 mRNA targets and increased RVFV replication. Therefore, RVFV competes for the Dcp2-accessible mRNA pool, which is dynamically regulated and can present a bottleneck for viral replication.