title: Phenylmethimazole blocks dsRNA-induced IRF3 nuclear translocation and homodimerization.
abstract: Previous studies revealed that phenylmethimazole (C10) inhibits IRF3 signaling, preventing dsRNA-induction of type 1 interferon gene expression, production, and downstream signaling. In the present study, we investigated the molecular basis for C10 inhibition of dsRNA-stimulated IRF3 signaling. IRF-3 Trans-AM assays were used to measure C10 effects on dsRNA induction of IRF3 DNA binding. Green fluorescent protein-labeled IRF3 was used to measure C10 effects on dsRNA-induced IRF3 nuclear translocation. Native PAGE, SDS PAGE, and western blotting were used to identify effects of C10 on IRF3 homodimer formation and phosphorylation, respectively. There was a significant impairment of dsRNA-induced IRF3 DNA binding activity in human embryonic kidney and pancreatic cancer cells with C10 treatment. C10 also blocked dsRNA-induced IRF3 nuclear translocation and homodimer formation without blocking serine 396 phosphorylation of IRF3. Together, these results indicate that C10 interferes with IRF3 signaling by blocking dsRNA-induced IRF3 homodimer formation, a prerequisite for nuclear translocation and DNA binding activities.
authors.affiliation: Department of Specialty Medicine, Ohio University, Athens, OH 45701, USA.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Courreges
authors.forename: Noriko
authors.initials: N
authors.lastname: Kantake
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Goetz
authors.forename: Frank L
authors.initials: FL
authors.lastname: Schwartz
authors.forename: Kelly D
authors.initials: KD
authors.lastname: McCall
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism*; D008713:Methimazole / Q000031:analogs & derivatives* / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects*; D021381:Protein Transport / Q000187:drug effects; D012330:RNA, Double-Stranded / Q000494:pharmacology*; D013871:Thiones / Q000494:pharmacology*
chemical_list: C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; D012330:RNA, Double-Stranded; D013871:Thiones; C489637:phenyl methimazole; D010768:Phosphoserine; D008713:Methimazole; D004247:DNA