Tight regulation of NF-κB signaling is essential for innate and adaptive immune responses, yet the molecular mechanisms responsible for its negative regulation are not completely understood. Here, we report that NLRX1, a NOD-like receptor family member, negatively regulates Toll-like receptor-mediated NF-κB activation. NLRX1 interacts with TRAF6 or IκB kinase (IKK) in an activation signal-dependent fashion. Upon LPS stimulation, NLRX1 is rapidly ubiquitinated, disassociates from TRAF6, and then binds to the IKK complex, resulting in inhibition of IKKα and IKKβ phosphorylation and NF-κB activation. Knockdown of NLRX1 in various cell types markedly enhances IKK phosphorylation and the production of NF-κB-responsive cytokines after LPS stimulation. We further provide in vivo evidence that NLRX1 knockdown in mice markedly enhances susceptibility to LPS-induced septic shock and plasma IL-6 level. Our study identifies a previously unrecognized role for NLRX1 in the negative regulation of TLR-induced NF-κB activation by dynamically interacting with TRAF6 and the IKK complex.
SciCrunch is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to scicrunch, however this is not currently a free service.