The TLR4/TRIF-Mediated Activation of NLRP3 Inflammasome Underlies Endotoxin-Induced Liver Injury in Mice

Figure 1

Inflammasome constituents. There have been reported at least four types of inflammasomes, NLRP1 (Nalp1), NLRP3 (Nalp3), NLRC4 (Ipaf), and AIM2 inflammasomes. NLR is subdivided into two groups, PYD-possessing group, namely, NLRP and PYD-lacking group NLRC. After exposure of cells to the corresponding stimuli, these NLRs and AIM2 are believed to be self-oligomerized. As it contains CARD at an N-terminus and PYD at a C-terminus, self-oligomerized NLRP1 can recruit procaspase (casp)-1 and procaspase-5 by action of its CARD and also assembly procaspase-1 with help from ASC that possesses both PYD and CARD. Self-oligomerized NLRP3 recruits procaspase-1 by interposing ASC between them. In contrast, self-oligomerized NLRC4 recruits procaspase-1 by directly interacting CARD of procaspase-1 with its CARD. AIM2, belonging a different protein family, is also believed to be self-oligomerized after recognition of double-stranded DNA and recruits procaspase-1 with help from ASC. NLR, Nod-like receptor; CARD, caspase recruitment domain; PYD, pyrin domain.