title: A short hairpin RNA screen of interferon-stimulated genes identifies a novel negative regulator of the cellular antiviral response.
abstract: The type I interferon (IFN) signaling pathway restricts infection of many divergent families of RNA and DNA viruses by inducing hundreds of IFN-stimulated genes (ISGs), some of which have direct antiviral activity. We screened 813 short hairpin RNA (shRNA) constructs targeting 245 human ISGs using a flow cytometry approach to identify genes that modulated infection of West Nile virus (WNV) in IFN-β-treated human cells. Thirty ISGs with inhibitory effects against WNV were identified, including several novel genes that had antiviral activity against related and unrelated positive-strand RNA viruses. We also defined one ISG, activating signal cointegrator complex 3 (ASCC3), which functioned as a negative regulator of the host defense response. Silencing of ASCC3 resulted in upregulation of multiple antiviral ISGs, which correlated with inhibition of infection of several positive-strand RNA viruses. Reciprocally, ectopic expression of human ASCC3 or mouse Ascc3 resulted in downregulation of ISGs and increased viral infection. Mechanism-of-action and RNA sequencing studies revealed that ASCC3 functions to modulate ISG expression in an IRF-3- and IRF-7-dependent manner. Compared to prior ectopic ISG expression studies, our shRNA screen identified novel ISGs that restrict infection of WNV and other viruses and defined a new counterregulatory ISG, ASCC3, which tempers cell-intrinsic immunity.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Jianqing
authors.initials: J
authors.lastname: Li
authors.forename: Steve C
authors.initials: SC
authors.lastname: Ding
authors.forename: Hyelim
authors.initials: H
authors.lastname: Cho
authors.forename: Brian C
authors.initials: BC
authors.lastname: Chung
authors.forename: Michael
authors.initials: M
authors.lastname: Gale
authors.forename: Sumit K
authors.initials: SK
authors.lastname: Chanda
authors.forename: Michael S
authors.initials: MS
authors.lastname: Diamond
mesh_terms: D000818:Animals; D002460:Cell Line; D004265:DNA Helicases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation; D005820:Genetic Testing / Q000379:methods; D054884:Host-Pathogen Interactions; D006801:Humans; D007372:Interferons / Q000276:immunology*; D051379:Mice; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D014902:West Nile virus / Q000276:immunology*
chemical_list: D034741:RNA, Small Interfering; D007372:Interferons; C584453:ASCC3 protein, human; D004265:DNA Helicases