A Baculovirus-Encoded MicroRNA (miRNA) Suppresses Its Host miRNA Biogenesis by Regulating the Exportin-5 Cofactor Ran
A Baculovirus-Encoded MicroRNA (miRNA) Suppresses Its Host miRNA Biogenesis by Regulating the Exportin-5 Cofactor Ran
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DOI：
10.1128/jvi.00064-12
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发表时间：
2012-08-01
影响因子：
5.4
通讯作者：
Nagaraju, J.
中科院分区：
文献类型：
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作者：
Singh, C. P.;Singh, J.;Nagaraju, J.
MicroRNAs在真核生物的各种生物学过程中扮演着重要角色，包括宿主与病原体的相互作用。最近的研究表明，病毒通过编码miRNAs来操纵宿主基因的表达，以确保其有效的增殖，而宿主通过差异表达针对关键病毒基因的miRNAs来限制病毒感染。在这里，我们证明了一种昆虫病毒，家蚕核型多角体病毒(BmNPV)，通过编码一种miRNA(bmnpv-miR-1)下调宿主GTP结合核蛋白RAN的表达，从而调节小RNA介导的对宿主B.mori的防御。我们通过细胞培养和体内实验证明了bmnpv-miR-1与RAN mRNA的序列依赖性相互作用，包括对RAN的RNA干扰(RNAi)。我们的结果清楚地表明，bmnpv-miR-1抑制Ran，导致宿主小RNA种群减少，从而增加感染幼虫中的BmNPV载量。阻断bmnpv-miR-1后，RAN表达增加，BmNPV增殖下降。相反，阻断宿主miRNA BMO-miR-8(针对病毒的即刻早期基因，其生产被抑制在bmnpv-miR-1上并运行dsRNA注射)，导致受感染的家蚕幼虫的病毒载量显著增加。本研究深入了解了该病毒为有效繁殖而采用的一种逃避寄主防御的策略，并对昆虫病毒控制策略的发展具有一定的指导意义。
MicroRNAs have emerged as key players in the regulation of various biological processes in eukaryotes, including host-pathogen interactions. Recent studies suggest that viruses encode miRNAs to manipulate their host gene expression to ensure their effective proliferation, whereas the host limits virus infection by differentially expressing miRNAs that target essential viral genes. Here, we demonstrate that an insect virus, Bombyx mori nucleopolyhedrosis virus (BmNPV), modulates the small-RNA-mediated defense of its host, B. mori, by encoding an miRNA (bmnpv-miR-1) that downregulates the expression of the host GTP-binding nuclear protein Ran, an essential component of the exportin-5-mediated nucleocytoplasmic transport machinery mainly involved in small-RNA transport from the nucleus to the cytoplasm. We demonstrate the sequence-dependent interaction of bmnpv-miR-1 with Ran mRNA using cell culture and in vivo assays, including RNA interference (RNAi) of Ran. Our results clearly show that bmnpv-miR-1 represses Ran, leading to reduction in the host small-RNA population, and consequently, the BmNPV load increases in the infected larvae. Blocking of bmnpv-miR-1 resulted in higher expression levels of Ran and a decrease in BmNPV proliferation. In contrast, blockage of host miRNA, bmo-miR-8, which targets the immediate-early gene of the virus and whose production was repressed upon bmnpv-miR-1 and Ran dsRNA administration, resulted in a significant increase in the virus load in the infected B. mori larvae. The present study provides an insight into one of the evasion strategies used by the virus to counter the host defense for its effective proliferation and has relevance to the development of insect virus control strategies.