title: Nedd8 regulates inflammasome-dependent caspase-1 activation.
abstract: Caspase-1 is activated by the inflammasome complex to process cytokines like interleukin-1β (IL-1β). Pro-caspase-1 consists of three domains, CARD, p20, and p10. Association of pro-caspase-1 with the inflammasome results in initiation of its autocatalytic activity, culminating in self-cleavage that generates catalytically active subunits (p10 and p20). In the current study, we show that Nedd8 is required for efficient self-cleavage of pro-caspase-1 to generate its catalytically active subunits. Nedd8 silencing or treating cells with the neddylation inhibitor MLN4924 led to diminished caspase-1 processing and reduced IL-1β maturation following inflammasome activation. Coimmunoprecipitation and mass spectrometric analysis of 293 cells overexpressing pro-caspase-1 (and CARD) and Nedd8 suggested possible neddylation of caspase-1 CARD. Following inflammasome activation in primary macrophages, we observed colocalization of endogenous Nedd8 with caspase-1. Similarly, interaction of endogenous Nedd8 with caspase-1 CARD was detected in inflammasome-activated macrophages. Furthermore, enhanced autocatalytic activity of pro-caspase-1 was observed following Nedd8 overexpression in 293 cells, and such activity in inflammasome-activated macrophages was drastically diminished upon treatment of cells with MLN4924. Thus, our studies demonstrate a role of Nedd8 in regulating caspase-1 activation following inflammasome activation, presumably via augmenting autoprocessing/cleavage of pro-caspase-1 into its corresponding catalytically active subunits.
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Jesus A
authors.initials: JA
authors.lastname: Segovia
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Su-Yu
authors.initials: SY
authors.lastname: Tsai
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Te-Hung
authors.initials: TH
authors.lastname: Chang
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA.
authors.forename: Niraj K
authors.initials: NK
authors.lastname: Shil
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Susan T
authors.initials: ST
authors.lastname: Weintraub
authors.affiliation: Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Short
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA sbose@vetmed.wsu.edu.
authors.forename: Santanu
authors.initials: S
authors.lastname: Bose
mesh_terms: D000818:Animals; D002352:Carrier Proteins; D020170:Caspase 1 / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D058847:Inflammasomes / Q000378:metabolism*; D009980:Influenza A virus / Q000302:isolation & purification*; D053583:Interleukin-1beta / Q000096:biosynthesis; D008264:Macrophages / Q000378:metabolism / Q000821:virology; D008810:Mice, Inbred C57BL; D000075687:NEDD8 Protein; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D000075687:NEDD8 Protein; C082860:NEDD8 protein, human; C513172:Nedd8 protein, mouse; D014452:Ubiquitins; D020170:Caspase 1