title: Pivotal role of KARAP/DAP12 adaptor molecule in the natural killer cell-mediated resistance to murine cytomegalovirus infection.
abstract: Natural killer (NK) cells are major contributors to early defense against infections. Their effector functions are controlled by a balance between activating and inhibiting signals. To date, however, the involvement of NK cell activating receptors and signaling pathways in the defense against pathogens has not been extensively investigated. In mice, several NK cell activating receptors are coexpressed with and function through the immunoreceptor tyrosine-based activation motif (ITAM)-bearing molecule KARAP/DAP12. Here, we have analyzed the role of KARAP/DAP12 in the early antiviral response to murine cytomegalovirus (MCMV). In KARAP/DAP12 mutant mice bearing a nonfunctional ITAM, we found a considerable increase in viral titers in the spleen (30-40-fold) and in the liver (2-5-fold). These effects were attributed to NK cells. The formation of hepatic inflammatory foci appeared similar in wild-type and mutant mice, but the latter more frequently developed severe hepatitis with large areas of focal necrosis. Moreover, the percentage of hepatic NK cells producing interferon gamma was reduced by 56 +/- 22% in the absence of a functional KARAP/DAP12. This is the first study that shows a crucial role for a particular activating signaling pathway, in this case the one induced through KARAP/DAP12, in the NK cell-mediated resistance to an infection. Our results are discussed in relation to recent reports demonstrating that innate resistance to MCMV requires the presence of NK cells expressing the KARAP/DAP12-associated receptor Ly49H.
authors.affiliation: Microbiology and Tumor Biology Center, Karolinska Institute, S 171 77 Stockholm, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Sjölin
authors.forename: Elena
authors.initials: E
authors.lastname: Tomasello
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Mousavi-Jazi
authors.forename: Armando
authors.initials: A
authors.lastname: Bartolazzi
authors.forename: Klas
authors.initials: K
authors.lastname: Kärre
authors.forename: Eric
authors.initials: E
authors.lastname: Vivier
authors.forename: Cristina
authors.initials: C
authors.lastname: Cerboni
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D003433:Crosses, Genetic; D003586:Cytomegalovirus Infections / Q000276:immunology*; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000032:analysis; D007694:Killer Cells, Natural / Q000276:immunology*; D007962:Leukocytes / Q000276:immunology; D008107:Liver Diseases / Q000276:immunology / Q000473:pathology / Q000821:virology; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D008565:Membrane Proteins; D011971:Receptors, Immunologic; C110546:TYROBP protein, human; D007371:Interferon-gamma