Summary: Small heterodimer partner (SHP) is an orphan nuclear receptor that acts as a transcriptional co-repressor by interacting with nuclear receptors and transcription factors. Although SHP plays a negative regulatory function in various signaling pathways, its role in virus infection has not been studied. Here, we report that SHP is a potent negative regulator of the virus-mediated type I IFN signaling that maintains homeostasis within the antiviral innate immune system. Upon virus infection, SHP interacts specifically with CREB-binding protein (CBP) in the nucleus, thereby obstructing CBP/β-catenin interaction competitively. Consequently, SHP-deficient cells enhance antiviral responses, including transcription of the type I IFN gene, upon virus infection. Furthermore, SHP-deficient mice show higher levels of IFN production and are more resistant to influenza A virus infection. Our results suggest that SHP is a nuclear regulator that blocks transcription of the type I IFN gene to inhibit excessive innate immune responses. : Interferon (IFN), which has an antiviral effect, must be tightly modulated to prevent excessive induction that adversely affects the host. Kim et al. demonstrate that SHP acts as negative regulator of type I IFN signaling, which inhibits IFN gene transcription by blocking the interaction of CBP and β-catenin. Keywords: SHP, type I interferon, CBP, β-catenin
Full Text Finder