title: Nod1, a CARD protein, enhances pro-interleukin-1beta processing through the interaction with pro-caspase-1.
abstract: The production of bioactive interleukin-1beta (IL-1beta), a pro-inflammatory cytokine, is mediated by activated caspase-1. One of the known molecular mechanisms underlying pro-caspase-1 processing and activation involves interaction between the caspase recruit domains (CARDs) of caspase-1 and a serine/threonine kinase RIP2. While the association of Nod1 with both caspase-1 and RIP2 is already known, the consequences of these interactions are poorly understood. Because Nod1 also binds to RIP2, we hypothesized that Nod1 plays a role in pro-caspase-1 activation and IL-1beta processing. We show here that Nod1 binds to both RIP2 and caspase-1 by CARD interactions. Nod1 enhances pro-caspase-1 oligomerization and pro-caspase-1 processing. Nod1 enhances caspase-1-induced IL-1beta secretion, as well as lipopolysaccharide (LPS)-induced IL-1beta secretion in transfected cells. Moreover, HT1080 cells stably transfected with Nod1 showed higher LPS-induced IL-1beta secretion than non-transfected cells, suggesting a role of Nod1 in LPS-induced responses. Our data indicate that Nod1 can regulate IL-1beta secretion, implying that Nod1 may play a role in inflammatory responses to bacterial LPS.
authors.affiliation: Department of Pathology, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, South Korea.
authors.forename: Nam Jin
authors.initials: NJ
authors.lastname: Yoo
authors.forename: Won Sang
authors.initials: WS
authors.lastname: Park
authors.forename: Su Young
authors.initials: SY
authors.lastname: Kim
authors.forename: John C
authors.initials: JC
authors.lastname: Reed
authors.forename: Seong Gon
authors.initials: SG
authors.lastname: Son
authors.forename: Jung Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Sug Hyung
authors.initials: SH
authors.lastname: Lee
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism*; D020170:Caspase 1; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D051379:Mice; D053474:Nod1 Signaling Adaptor Protein; D011498:Protein Precursors / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004792:Enzyme Precursors; D007375:Interleukin-1; D008070:Lipopolysaccharides; C119067:NOD1 protein, human; D053474:Nod1 Signaling Adaptor Protein; D011498:Protein Precursors; D018160:Receptors, Cytoplasmic and Nuclear; D017346:Protein Serine-Threonine Kinases; C506253:RIPK2 protein, human; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C506255:Ripk2 protein, mouse; D020169:Caspases; D020170:Caspase 1