Phenylmethimazole blocks dsRNA-induced IRF3 nuclear translocation and homodimerization

• Published in: Molecules (Basel, Switzerland) Vol. 17; no. 10; pp. 12365 - 12377
• Main Authors: Courreges, Maria C, Kantake, Noriko, Goetz, Douglas J, Schwartz, Frank L, McCall, Kelly D
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 22.10.2012; MDPI
• Subjects: Cell Line, Tumor; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Diabetes; DNA - metabolism; Engineering schools; Gene expression; HEK293 Cells; Humans; Inflammatory diseases; Interferon; Interferon Regulatory Factor-3 - metabolism; IRF3; Kinases; Methimazole - analogs & derivatives; Methimazole - pharmacology; Pancreatic cancer; phenylmethimazole (C10); Phosphorylation; Phosphorylation - drug effects; Phosphoserine - metabolism; Protein Binding - drug effects; Protein Multimerization - drug effects; Protein Transport - drug effects; Proteins; RNA, Double-Stranded - pharmacology; Thiones - pharmacology; Tumor necrosis factor-TNF; University colleges; Viral infections; United States > US; Ohio
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules171012365

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.