Pellino3 targets the IRF7 pathway and facilitates autoregulation of TLR3- and viral-induced expression of type I interferons

Signaling through toll-like receptors induces cytokines and type I interferon. Moynagh and colleagues show that the E3 ubiquitin ligase Pellino3 specifically represses the expression of type I interferon in response to TLR3 activation. Toll-like receptors (TLRs) sense pathogen-associated molecules and respond by inducing cytokines and type I interferon. Here we show that genetic ablation of the E3 ubiquitin ligase Pellino3 augmented the expression of type I interferon but not of proinflammatory cytokines in response to TLR3 activation. Pellino3-deficient mice had greater resistance against the pathogenic and lethal effects of encephalomyocarditis virus (EMCV). TLR3 signaling induced Pellino3, which in turn interacted with and ubiquitinated TRAF6. This modification suppressed the ability of TRAF6 to interact with and activate IRF7, resulting in downregulation of type I interferon expression. Our findings highlight a new physiological role for Pellino3 and define a new autoregulatory network for controlling type I interferon expression.