title: RICK/Rip2/CARDIAK mediates signalling for receptors of the innate and adaptive immune systems.
abstract: The immune system consists of two evolutionarily different but closely related responses, innate immunity and adaptive immunity. Each of these responses has characteristic receptors-Toll-like receptors (TLRs) for innate immunity and antigen-specific receptors for adaptive immunity. Here we show that the caspase recruitment domain (CARD)-containing serine/threonine kinase Rip2 (also known as RICK, CARDIAK, CCK and Ripk2) transduces signals from receptors of both immune responses. Rip2 was recruited to TLR2 signalling complexes after ligand stimulation. Moreover, cytokine production in Rip2-deficient cells was reduced on stimulation of TLRs with lipopolysaccharide, peptidoglycan and double-stranded RNA, but not with bacterial DNA, indicating that Rip2 is downstream of TLR2/3/4 but not TLR9. Rip2-deficient cells were also hyporesponsive to signalling through interleukin (IL)-1 and IL-18 receptors, and deficient for signalling through Nod proteins-molecules also implicated in the innate immune response. Furthermore, Rip2-deficient T cells showed severely reduced NF-kappaB activation, IL-2 production and proliferation on T-cell-receptor (TCR) engagement, and impaired differentiation to T-helper subtype 1 (TH1) cells, indicating that Rip2 is required for optimal TCR signalling and T-cell differentiation. Rip2 is therefore a signal transducer and integrator of signals for both the innate and adaptive immune systems.
authors.affiliation: Section of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Naohiro
authors.initials: N
authors.lastname: Inohara
authors.forename: Lorraine D
authors.initials: LD
authors.lastname: Hernandez
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Galán
authors.forename: Gabriel
authors.initials: G
authors.lastname: Núñez
authors.forename: Charles A
authors.initials: CA
authors.lastname: Janeway
authors.forename: Ruslan
authors.initials: R
authors.lastname: Medzhitov
authors.forename: Richard A
authors.initials: RA
authors.lastname: Flavell
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D029721:Drosophila Proteins; D017353:Gene Deletion; D007113:Immunity, Innate / Q000276:immunology*; D007378:Interleukins / Q000096:biosynthesis / Q000276:immunology; D047908:Intracellular Signaling Peptides and Proteins; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D008089:Listeria monocytogenes / Q000276:immunology / Q000502:physiology; D008088:Listeriosis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D053474:Nod1 Signaling Adaptor Protein; D053473:Nod2 Signaling Adaptor Protein; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D018121:Receptors, Cytokine / Q000096:biosynthesis; D018123:Receptors, Interleukin / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D029721:Drosophila Proteins; C104577:IP10-Mig receptor; D007378:Interleukins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; C119067:NOD1 protein, human; C429018:NOD2 protein, human; D053474:Nod1 Signaling Adaptor Protein; D053473:Nod2 Signaling Adaptor Protein; D011948:Receptors, Antigen, T-Cell; D011956:Receptors, Cell Surface; D018121:Receptors, Cytokine; D018123:Receptors, Interleukin; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; 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