Viperin weakens IFN-I antiviral immunity by facilitating STAT1 degradation via E3 ligase UBE4A

The type-I interferon (IFN-I) pathway is a cornerstone of the innate immune response, crucial for host defense against viral infections. Activation of this pathway leads to the phosphorylation and nuclear translocation of STAT1, initiating the transcription of antiviral genes. While Viperin is recognized as an antiviral protein, directly targeting various viruses, its potential role in modulating intracellular immune signaling, particularly the IFN-I pathway, has remained largely unexplored. Understanding how Viperin interacts with host immune components could reveal novel regulatory mechanisms and therapeutic targets to enhance antiviral strategies.

Researchers investigated the molecular mechanisms by which Viperin influences type-I interferon (IFN-I) antiviral immunity. They employed a combination of cellular and biochemical assays to identify key protein-protein interactions and ubiquitination events. The study characterized Viperin's role in modulating STAT1 stability and its interactions with various ubiquitin E3 ligases, specifically focusing on UBE4A and ITCH. Furthermore, the team explored the therapeutic potential of a novel multifunctional interfering peptide, VS-IP1, to counteract Viperin-mediated STAT1 degradation and enhance IFN-I signaling.

The study revealed a novel immunosuppressive role for Viperin within the IFN-I pathway. They found that Viperin actively inhibits IFN-I antiviral immune signaling by promoting the degradation of the crucial transcription factor STAT1. Mechanistically, IFN-I signaling was shown to upregulate the ubiquitin E3 ligase ITCH, which in turn degrades UBR5. This cascade appears to set the stage for Viperin's action. > Viperin subsequently recruits another ubiquitin E3 ligase, UBE4A, to specifically promote the ubiquitination and degradation of STAT1, thereby attenuating the IFN-I response. Crucially, the multifunctional interfering peptide VS-IP1 was demonstrated to effectively block this Viperin-mediated STAT1 degradation, leading to an enhancement of IFN-I antiviral immune function.