Establishing the balance between positive and negative innate immune mechanisms is crucial for maintaining homeostasis. Here we uncover the regulatory crosstalk between two previously unlinked innate immune receptor families: RIG-I, an anti-viral cytosolic receptor activated type I interferon production, and NLR (nucleotide-binding domain, leucine repeat domain-containing protein). We show that NLRP12 dampens RIG-I-mediated immune signaling against RNA viruses by controlling RIG-I's association with its adaptor MAVS. The nucleotide-binding domain of NLRP12 interacts with the ubiquitin ligase TRIM25 to prevent TRIM25-mediated, Lys63-linked ubiquitination and activation of RIG-I. NLRP12 also enhances RNF125-mediated, Lys48-linked degradative ubiquitination of RIG-I. Vesicular stomatitis virus (VSV) infection downregulates NLRP12 expression to allow RIG-I activation. Myeloid-cell-specific Nlrp12-deficient mice display a heightened interferon and TNF response and are more resistant to VSV infection. These results indicate that NLRP12 functions as a checkpoint for anti-viral RIG-I activation. Chen et al. show that the nucleotide-binding domain and leucine repeat domain-containing protein NLRP12 associates with the ubiquitin ligase TRIM25 to reduce K63-linked ubiquitination of the anti-viral innate immune receptor RIG-I. This prevents RIG-I association with MAVS and thus serves as a checkpoint for interferon and cytokine induction in response to RNA viruses.
ASJC Scopus subject areas