Study On The Mechanism Of Deubiquitinating Enzyme USP13 In Promoting The Activation Of NLRP3 Inflammasome

NOD-like receptor family pyrin domain-containing 3(NLRP3)protein is an important intracellular sensor of the body,which can recognize a variety of Pathogen-associated molecular and Damage-associated molecular.After activation,it forms NLRP3 inflammasomes with ASC and Pro-Caspase-1,and promotes the maturation and secretion of inflammatory mediators such as IL-1β and IL-18,thereby promoting the inflammatory response.NLRP3 inflammasome is an important barrier for the host to resist the invasion of pathogens,but its abnormal activation is closely related to the occurrence and development of cold pyridine-related periodic syndrome,Alzheimer’s disease,non-alcoholic fatty liver disease,arthritis and other diseases.The expression of NLRP3 is regulated by transcription,translation and post-translational modification.The regulation of its protein stability is of great significance to the activation of NLRP3,but the mechanism has not been fully revealed.Ubiquitin-specific protease 13(USP13)is one of the members of the USP deubiquitinating enzyme family.It mainly functions to remove the K48-linked ubiquitin chains and inhibits its substrate degradation through the ubiquitin proteasome pathway.This paper uses USP13 knockout mice to find that the deletion of USP13 significantly inhibits the activation of NLRP3 inflammasomes in mouse bone marrow-derived macrophages(BMDMs),which is manifested by reducing the secretion of IL-1β induced by NLRP3 agonists,inhibiting the maturation of Caspase-1and IL-1β,and blocking the assembly of NLRP3 inflammasome,including the formation of ASC specks and the interaction between NLRP3 and ASC.Co-immunoprecipitation experiments in 293 T cells proved that USP13 interacts with NLRP3.USP13 binds to the N-terminal 6-89 amino acid region(6-89aa)of the NLRP3 protein,and NLRP3 binds to the C-terminal 624-863 aa region of the USP13 protein.Overexpression of USP13 selectively removes the K48-linked ubiquitinchains of NLRP3,prolongs the half-life of NLRP3 protein,and improves the stability of NLRP3 protein.In BMDMs,USP13 deficiency substantially increased the ubiquitination of resting NLRP3 and inhibited the K48-linked deubiquitination of NLRP3 induced by LPS,thereby reducing the stability of NLRP3 protein.Together,this paper found a new function of USP13 in regulating the activation of NLRP3 inflammasome and revealed a new mechanism for maintaining the stability of NLRP3 protein,which may provide a potential therapeutic target for NLRP3-related diseases.