title: Importin β1 targeting by hepatitis C virus NS3/4A protein restricts IRF3 and NF-κB signaling of IFNB1 antiviral response.
abstract: In this study, newly identified host interactors of hepatitis C virus (HCV) proteins were assessed for a role in modulating the innate immune response. The analysis revealed enrichment for components of the nuclear transport machinery and the crucial interaction with NS3/4A protein in suppression of interferon-β (IFNB1) induction. Using a comprehensive microscopy-based high-content screening approach combined to the gene silencing of nuclear transport factors, we showed that NS3/4A-interacting proteins control the nucleocytoplasmic trafficking of IFN regulatory factor 3 (IRF3) and NF-κB p65 upon Sendai virus (SeV) infection. Notably, importin β1 (IMPβ1) knockdown-a hub protein highly targeted by several viruses-decreases the nuclear translocation of both transcription factors and prevents IFNB1 and IFIT1 induction, correlating with a rapid increased of viral proteins and virus-mediated apoptosis. Here we show that NS3/4A triggers the cleavage of IMPβ1 and inhibits nuclear transport to disrupt IFNB1 production. Importantly, mutated IMPβ1 resistant to cleavage completely restores signaling, similar to the treatment with BILN 2061 protease inhibitor, correlating with the disappearance of cleavage products. Overall, the data indicate that HCV NS3/4A targeting of IMPβ1 and related modulators of IRF3 and NF-κB nuclear transport constitute an important innate immune subversion strategy and inspire new avenues for broad-spectrum antiviral therapies.
authors.affiliation: Centre de Recherche du CHUM (CRCHUM), Montréal, Canada.|Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, Canada.
authors.forename: Bridget
authors.initials: B
authors.lastname: Gagné
authors.affiliation: Centre de Recherche du CHUM (CRCHUM), Montréal, Canada.|Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, Canada.
authors.forename: Nicolas
authors.identifier: 0000-0003-4246-7189
authors.initials: N
authors.lastname: Tremblay
authors.affiliation: Centre de Recherche du CHUM (CRCHUM), Montréal, Canada.|Département de Microbiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, Canada.
authors.forename: Alex Y
authors.initials: AY
authors.lastname: Park
authors.affiliation: Centre de Recherche du CHUM (CRCHUM), Montréal, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Baril
authors.affiliation: Centre de Recherche du CHUM (CRCHUM), Montréal, Canada.|Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lamarre
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000276:immunology; D002352:Carrier Proteins / Q000378:metabolism*; D016174:Hepacivirus; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D028884:Karyopherins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D028961:beta Karyopherins / Q000378:metabolism*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D050838:Interferon Regulatory Factor-3; D047908:Intracellular Signaling Peptides and Proteins; D028884:Karyopherins; D016328:NF-kappa B; D011480:Protease Inhibitors; D017361:Viral Nonstructural Proteins; D028961:beta Karyopherins; C424166:KPNB1 protein, human; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C455041:NS4A cofactor peptide, Hepatitis C virus
keywords: HCV; IMPβ1/KPNB1; IRF3; NF-κB p65; NPC; NS3/4A protein; RNAi screen; SeV; importin-α; importin-β; innate antiviral immunity; interferon-β; microscopy-based high-content screening; nuclear pore complex; nuclear translocation; nucleocytoplasmic transport; virus-host interaction