NLRP4 (or NACHT, LRR and PYD domains-containing protein 4) and E3 ubiquitin-protein ligase DTX4 were reported to regulate the activation of type I interferon induced by double-stranded RNA or DNA (Cui J et al. 2012). Co-transfection with various combinations of full-length and truncated NLRP4 and DTX4 proteins in human embryonic kidney HEK293T cells, followed by IFN-signaling reporter assays and immunoassays showed that Nod domain of NLRP4 regulated TBK1 activity by recruiting DTX4 through the RING domain to the kinase domain of TBK1. The E3-ligase activity of DTX4 promoted K48-linked ubiquitination of TBK1 targeting it to the proteosomal degradation.The NLRP4 and DTX4 knockdown by siRNA in peripheral blood mononuclear cells (PBMCs) and THP-1 cells resulted in higher type I interferon production following stimulation with vesicular stomatitis virus (VSV), Sendai virus, and transfected Poly(dA:dT), which may engage various cytosolic receptors to activate IFN regulatory factor 3 (IRF3) downstream of TBK1 (Cui J et al. 2012).