The ubiquitin-specific protease 17 is involved in virus-triggered type I IFN signaling

Viral infection initiates a series of signaling cascades that activate the transcription factors nuclear factor kappa B and interferon regulatory factor 3, which collaborate to induce transcription of genes for type I interferons (IFNs) and other cytokines. Here we report that the deubiquitinating enzyme ubiquitin-specific protease 17 (USP17) is required for virus-induced RIG-I- and melanoma differentiation-associated protein-5 (MDA5)-mediated type I IFN signaling. Knockdown of endogenous USP17 inhibited virus-, cytoplasmic poly(I:C)- and poly(dA:dT)-induced activation of the IFN-beta promoter and cellular antiviral responses. We further found that knockdown of USP17 inhibited RIG-I-and MDA5-induced but not downstream activator-induced activation of the IFN-beta promoter, which was correlated with an increase in ubiquitination levels of RIG-I and MDA5. Taken together, our findings suggest that USP17 functions through deubiquitination of RIG-I and MDA5 to regulate virus-induced type I IFN signaling.