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.