Understanding the Biological Context of NS5A–Host Interactions in HCV Infection: A Network-Based Approach

Hepatitis
C virus (HCV) is a major cause of chronic liver disease.
HCV NS5A protein plays an important role in HCV infection through
its interactions with other HCV proteins and host factors. In an attempt
to further our understanding of the biological context of protein
interactions between NS5A and host factors in HCV pathogenesis, we
generated an extensive physical interaction map between NS5A and cellular
factors. By combining a yeast two-hybrid assay with comprehensive
literature mining, we built the NS5A interactome composed of 132 human
proteins that interact with NS5A. These interactions were integrated
into a high-confidence human protein interactome (HPI) with the help
of the TargetMine data warehouse system to infer an overall protein
interaction map linking NS5A with the components of the host cellular
networks. The NS5A–host interactions that were integrated with
the HPI were shown to participate in compact and well-connected cellular
networks. Functional analysis of the NS5A “infection”
network using TargetMine highlighted cellular pathways associated
with immune system, cellular signaling, cell adhesion, cellular growth
and death among others, which were significantly targeted by NS5A–host
interactions. In addition, cellular assays with in vitro HCV cell
culture systems identified two ER-localized host proteins RTN1 and
RTN3 as novel regulators of HCV propagation. Our analysis builds upon
the present understanding of the role of NS5A protein in HCV pathogenesis
and provides potential targets for more effective anti-HCV therapeutic
intervention.

丙型肝炎病毒（Hepatitis C virus, HCV）是引发慢性肝脏疾病的主要致病原。HCV NS5A蛋白可通过与其他HCV蛋白及宿主因子相互作用，在HCV感染过程中发挥关键功能。为进一步阐明NS5A与宿主因子在HCV致病过程中的蛋白质相互作用的生物学机制，我们构建了NS5A与细胞因子之间的大规模物理相互作用图谱。通过结合酵母双杂交试验与全面的文献挖掘，我们构建了包含132种与NS5A相互作用的人类蛋白的NS5A相互作用组。借助TargetMine数据仓库系统，我们将这些相互作用整合至高置信度人类蛋白相互作用组（HPI）中，以此推导得到将NS5A与宿主细胞网络组分相连的整体蛋白质相互作用图谱。与HPI整合后的NS5A-宿主相互作用被证实参与形成了紧凑且连接紧密的细胞网络。利用TargetMine对NS5A「感染」网络开展功能分析后发现，免疫系统、细胞信号传导、细胞黏附、细胞生长与死亡等多条细胞通路均为NS5A-宿主相互作用的显著靶向通路。此外，借助体外HCV细胞培养系统开展的细胞实验，我们鉴定出两种内质网（ER）定位的宿主蛋白RTN1与RTN3为HCV增殖的新型调控因子。本研究基于当前对NS5A蛋白在HCV致病过程中作用的认知，为开发更高效的抗HCV治疗干预手段提供了潜在靶点。