[PDF][PDF] NF-κB restricts inflammasome activation via elimination of damaged mitochondria

Z Zhong, A Umemura, E Sanchez-Lopez, S Liang… - Cell, 2016 - cell.com
Cell, 2016cell.com
Nuclear factor κB (NF-κB), a key activator of inflammation, primes the NLRP3-inflammasome
for activation by inducing pro-IL-1β and NLRP3 expression. NF-κB, however, also prevents
excessive inflammation and restrains NLRP3-inflammasome activation through a poorly
defined mechanism. We now show that NF-κB exerts its anti-inflammatory activity by
inducing delayed accumulation of the autophagy receptor p62/SQSTM1. External NLRP3-
activating stimuli trigger a form of mitochondrial (mt) damage that is caspase-1-and NLRP3 …
Summary
Nuclear factor κB (NF-κB), a key activator of inflammation, primes the NLRP3-inflammasome for activation by inducing pro-IL-1β and NLRP3 expression. NF-κB, however, also prevents excessive inflammation and restrains NLRP3-inflammasome activation through a poorly defined mechanism. We now show that NF-κB exerts its anti-inflammatory activity by inducing delayed accumulation of the autophagy receptor p62/SQSTM1. External NLRP3-activating stimuli trigger a form of mitochondrial (mt) damage that is caspase-1- and NLRP3-independent and causes release of direct NLRP3-inflammasome activators, including mtDNA and mtROS. Damaged mitochondria undergo Parkin-dependent ubiquitin conjugation and are specifically recognized by p62, which induces their mitophagic clearance. Macrophage-specific p62 ablation causes pronounced accumulation of damaged mitochondria and excessive IL-1β-dependent inflammation, enhancing macrophage death. Therefore, the "NF-κB-p62-mitophagy" pathway is a macrophage-intrinsic regulatory loop through which NF-κB restrains its own inflammation-promoting activity and orchestrates a self-limiting host response that maintains homeostasis and favors tissue repair.
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