Abstract：
Hepatitis C virus (HCV) is a positive-stranded RNA virus that mainly causes chronic hepatitis, cirrhosis and hepatocellular carcinoma. Recently we confirmed m5C modifications within NS5A gene of HCV RNA genome. However, the roles of the m5C modification and its interaction with host proteins in regulating HCV\'s life cycle, remain unexplored. Here, we demonstrate that HCV infection enhances the expression of the host m5C reader YBX1 through the transcription factor MAX. YBX1 acts as an m5C reader, recognizing the m5C-modified NS5A C7525 site in the HCV RNA genome and significantly enhancing HCV RNA stability. This m5C-modification is also required for YBX1 colocalization with lipid droplets and HCV Core protein. Moreover, YBX1 facilitates HCV RNA replication, as well as viral assembly/budding. The tryptophan residue at position 65 (W65) of YBX1 is critical for these functions. Knockout of YBX1 or the application of YBX1 inhibitor SU056 suppresses HCV RNA replication and viral protein translation. To our knowledge, this is the first report demonstrating that the interaction between host m5C reader YBX1 and HCV RNA m5C methylation facilitates viral replication. Therefore, hepatic-YBX1 knockdown holds promise as a potential host-directed strategy for HCV therapy.
摘要：
丙型肝炎病毒（HCV）是一种正链RNA病毒，主要引起慢性肝炎，肝硬化和肝细胞癌。最近，我们证实了HCVRNA基因组NS5A基因中的m5C修饰。然而,m5C修饰及其与宿主蛋白相互作用在调节HCV生命周期中的作用，仍未探索。这里,我们证明HCV感染通过转录因子MAX增强宿主m5C阅读器YBX1的表达。YBX1充当m5C阅读器，识别HCVRNA基因组中m5C修饰的NS5AC7525位点并显著增强HCVRNA稳定性。这种m5C修饰对于YBX1与脂滴和HCV核心蛋白的共定位也是必需的。此外，YBX1促进HCVRNA复制，以及病毒组装/出芽。YBX1的65位(W65)的色氨酸残基对于这些功能是关键的。敲除YBX1或应用YBX1抑制剂SU056抑制HCVRNA复制和病毒蛋白翻译。据我们所知,这是首次报告证明宿主m5C阅读器YBX1和HCVRNAm5C甲基化之间的相互作用促进病毒复制.因此,肝-YBX1敲除有望成为HCV治疗的潜在宿主导向策略.
