School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China.
School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, 212000, China; Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, 212000, China.
Dev Comp Immunol. 2022 Jun;131:104382. doi: 10.1016/j.dci.2022.104382. Epub 2022 Mar 1.
MicroRNAs (miRNAs) are small non-coding RNAs that function as novel gene expression regulators at the post-transcriptional level. Not with standing that the biogenesis and function of miRNAs are well-understood in eukaryotes, little is known about RNA virus-encoded miRNAs. Bombyx mori cypovirus (BmCPV) is a double-stranded RNA virus with a segmented genome that causes cytoplasmic polyhedrosis disease in silkworm larvae. To date, the interaction between BmCPV and silkworm remains largely unclear. 22 candidate BmCPV-encoded miRNAs were identified in this study through small RNA sequencing, stem-loop RT-PCR and qRT-PCR. Then, generation and function analyses were conducted on one of the candidate miRNAs, BmCPV-miR-1, in the BmN cells and the silkworm larvae by RNA interference, quantitative PCR, dual-luciferase assay. Our results revealed that BmCPV-miR-1 was encoded by BmCPV genome RNA rather than the degraded fragments of the viral genome. Its generation depended on Dicer-1 and might also be correlated with Dicer-2, Argonaute-1 and Argonaute-2. Moreover, BmCPV-miR-1 could suppress the expression of the target gene, B. mori inhibitor of nuclear factor kappa-B kinase subunit beta (BmIKKβ), via binding to the target mRNA 3'-untranslated region, which fine-tuned the host NF-κB signaling pathway and consequently enhanced viral replication. Our results provide new evidence supporting the hypothesis that RNA viruses could generate miRNAs to modulate antiviral host defense.
微小 RNA（miRNA）是一种小的非编码 RNA，作为新型基因表达调控因子在转录后水平发挥作用。尽管真核生物中 miRNA 的生物发生和功能已得到很好的理解，但对 RNA 病毒编码的 miRNA 知之甚少。家蚕质型多角体病毒（BmCPV）是一种双链 RNA 病毒，具有分段基因组，在家蚕幼虫中引起细胞质多角体病。迄今为止，BmCPV 与家蚕之间的相互作用在很大程度上仍不清楚。本研究通过小 RNA 测序、茎环 RT-PCR 和 qRT-PCR 鉴定了 22 个候选 BmCPV 编码 miRNA。然后，通过 RNA 干扰、定量 PCR 和双荧光素酶报告基因检测，对候选 miRNA 之一 BmCPV-miR-1 在 BmN 细胞和家蚕幼虫中的生成和功能进行了分析。我们的结果表明，BmCPV-miR-1 是由 BmCPV 基因组 RNA 编码的，而不是病毒基因组的降解片段。它的生成依赖于 Dicer-1，也可能与 Dicer-2、Argonaute-1 和 Argonaute-2 相关。此外，BmCPV-miR-1 可以通过结合靶 mRNA 3'-非翻译区来抑制靶基因 B. mori 核因子 kappa-B 激酶亚基β（BmIKKβ）的表达，从而精细调节宿主 NF-κB 信号通路，并最终增强病毒复制。我们的研究结果为 RNA 病毒产生 miRNA 来调节抗病毒宿主防御的假说提供了新的证据。
