title: Caspase-8 blocks kinase RIPK3-mediated activation of the NLRP3 inflammasome.
abstract: Caspase-8 deficiency in certain cells prompts chronic inflammation. One mechanism suggested to account for this inflammation is enhanced signaling for necrotic cell death, mediated by the protein kinases RIPK1 and RIPK3 that caspase-8 can cleave. We describe an activity of caspase-8 in dendritic cells that controls the initiation of inflammation in another way. Caspase-8 deficiency in these cells facilitated lipopolysaccharide-induced assembly and function of the NLRP3 inflammasome. This effect depended on the functions of RIPK1 and RIPK3, as well as of MLKL and PGAM5, two signaling proteins recently shown to contribute to RIPK3-mediated induction of necrosis. However, although enhancement of inflammasome assembly in the caspase-8-deficient cells shares proximal signaling events with the induction of necrosis, it occurred independently of cell death. These findings provide new insight into potentially pathological inflammatory processes to which RIPK1- and RIPK3-mediated signaling contributes.
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Tae-Bong
authors.initials: TB
authors.lastname: Kang
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Yang
authors.forename: Beata
authors.initials: B
authors.lastname: Toth
authors.forename: Andrew
authors.initials: A
authors.lastname: Kovalenko
authors.forename: David
authors.initials: D
authors.lastname: Wallach
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology; D053181:Caspase 8 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D017353:Gene Deletion; D058847:Inflammasomes / Q000235:genetics* / Q000276:immunology; D053583:Interleukin-1beta / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D051379:Mice; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation
chemical_list: D002352:Carrier Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C485615:Ripk3 protein, mouse; D053181:Caspase 8