We previously characterized conservation and divergence in Toll-like Receptor (TLR)4-dependent transcriptional responses in human versus mouse macrophages. In this study, we focused on orthologous human and mouse genes that were uniquely regulated by lipopolysaccharide (LPS) in human versus mouse macrophages and with putative mitochondrial functions. We confirmed “human-specific” LPS regulation of these genes by examining expression in primary human macrophages versus a panel of different mouse macrophage populations. In investigating potential functions, we found that one of these genes (a novel ubiquitin ligase) was required for NLRP3 inflammasome responses, as demonstrated by gene knock-down in both primary human macrophages and PMA-differentiated THP-1 cells. The NLRP3 inflammasome is a multi-protein complex containing NLRP3, ASC and caspase-1. Activation of the NLRP3 inflammasome results in the processing and release of the pro-inflammatory cytokines IL-1b and IL-18, as well as other pro-inflammatory products (e.g. HMGB1). NLRP3 assembly requires both a priming signal such as that delivered by the TLR4 agonist LPS, as well as a triggering signal such as damage-associated host molecules (e.g. ATP) or pathogen-associated stimuli. Recent studies have demonstrated that direct deubiquitination of NLRP3 is required for triggering of the NLRP3 inflammasome . Our findings now suggest that one of the mechanisms by which LPS primes NLRP3 inflammasome responses in human macrophages is via the upregulation of a specific ubiquitin ligase. Current studies are aimed at determining the specificity of this ubiquitin ligase in priming different inflammasomes, as well as identifying the substrate(s) required for inflammasome activation. Since dysregulation of the NLRP3 inflammasome is implicated in many inflammatory diseases such as arthritis, atherosclerosis, neurodegeneration and type 2 diabetes, our findings may provide new insights into pathological inflammatory processes.