Department of Microbiology & Immunology, McGill University, Montréal, Canada.
Department of Physiology, McGill University, Montréal, Canada.
Nucleic Acids Res. 2023 Mar 21;51(5):2447-2463. doi: 10.1093/nar/gkad094.
Efficient hepatitis C virus (HCV) RNA accumulation is dependent upon interactions with the human liver-specific microRNA, miR-122. MiR-122 has at least three roles in the HCV life cycle: it acts as an RNA chaperone, or 'riboswitch', allowing formation of the viral internal ribosomal entry site; it provides genome stability; and promotes viral translation. However, the relative contribution of each role in HCV RNA accumulation remains unclear. Herein, we used point mutations, mutant miRNAs, and HCV luciferase reporter RNAs to isolate each of the roles and evaluate their contribution to the overall impact of miR-122 in the HCV life cycle. Our results suggest that the riboswitch has a minimal contribution in isolation, while genome stability and translational promotion have similar contributions in the establishment phase of infection. However, in the maintenance phase, translational promotion becomes the dominant role. Additionally, we found that an alternative conformation of the 5' untranslated region, termed SLIIalt, is important for efficient virion assembly. Taken together, we have clarified the overall importance of each of the established roles of miR-122 in the HCV life cycle and provided insight into the regulation of the balance between viral RNAs in the translating/replicating pool and those engaged in virion assembly.
高效的丙型肝炎病毒 (HCV) RNA 积累依赖于与人肝脏特异性 microRNA miR-122 的相互作用。miR-122 在 HCV 生命周期中至少具有三个作用：它作为 RNA 伴侣，或“核酶”，允许病毒内部核糖体进入位点的形成；它提供基因组稳定性；并促进病毒翻译。然而，每种作用在 HCV RNA 积累中的相对贡献尚不清楚。在此，我们使用点突变、突变 miRNA 和 HCV 荧光素酶报告 RNA 来分离每种作用，并评估其对 miR-122 在 HCV 生命周期中的整体影响的贡献。我们的结果表明，在单独作用时，核酶的贡献最小，而基因组稳定性和翻译促进作用在感染的建立阶段具有相似的贡献。然而，在维持阶段，翻译促进作用成为主导作用。此外，我们发现 5'非翻译区的一种替代构象，称为 SLIIalt，对于有效的病毒体组装很重要。总之，我们已经阐明了 miR-122 在 HCV 生命周期中的每个既定作用的总体重要性，并深入了解了翻译/复制池中和参与病毒体组装的病毒 RNA 之间平衡的调节。
