TRIM30α negatively regulates TLR-mediated NF-κB activation by targeting TAB2 and TAB3 for degradation

Toll-like receptor (TLR) signaling is pivotal to innate and adaptive immune responses and must be tightly controlled. The mechanisms of TLR signaling have been the focus of extensive studies. Here we report that the tripartite-motif protein TRIM30 alpha, a RING protein, was induced by TLR agonists and interacted with the TAB2-TAB3-TAK1 adaptor-kinase complex involved in the activation of transcription factor NF-kappa B. TRIM30 alpha promoted the degradation of TAB2 and TAB3 and inhibited NF-kappa B activation induced by TLR signaling. In vivo studies showed that transfected or transgenic mice overexpressing TRIM30a were more resistant to endotoxic shock. Consistent with that, in vivo 'knockdown' of TRIM30a mRNA by small interfering RNA impaired lipopolysaccharide-induced tolerance. Finally, expression of TRIM30a depended on NF-kappa B activation. Our results collectively indicate that TRIM30a negatively regulates TLR-mediated NF-kappa B activation by targeting degradation of TAB2 and TAB3 by a 'feedback' mechanism.