title: Interferon-Dependent Induction of Clr-b during Mouse Cytomegalovirus Infection Protects Bystander Cells from Natural Killer Cells via NKR-P1B-Mediated Inhibition.
abstract: Natural killer (NK) cells are innate lymphocytes that aid in self-nonself discrimination by recognizing cells undergoing pathological alterations. The NKR-P1B inhibitory receptor recognizes Clr-b, a self-encoded marker of cell health downregulated during viral infection. Here, we show that Clr-b loss during mouse cytomegalovirus (MCMV) infection is predicated by a loss of Clr-b (Clec2d) promoter activity and nascent transcripts, driven in part by MCMV ie3 (M122) activity. In contrast, uninfected bystander cells near MCMV-infected fibroblasts reciprocally upregulate Clr-b expression due to paracrine type-I interferon (IFN) signaling. Exposure of fibroblasts to type-I IFN augments Clec2d promoter activity and nascent Clr-b transcripts, dependent upon a cluster of IRF3/7/9 motifs located ∼200 bp upstream of the transcriptional start site. Cells deficient in type-I IFN signaling components revealed IRF9 and STAT1 as key transcription factors involved in Clr-b upregulation. In chromatin immunoprecipitation experiments, the Clec2d IRF cluster recruited STAT2 upon IFN-α exposure, confirming the involvement of ISGF3 (IRF9/STAT1/STAT2) in positively regulating the Clec2d promoter. These findings demonstrate that Clr-b is an IFN-stimulated gene on healthy bystander cells, in addition to a missing-self marker on MCMV-infected cells, and thereby enhances the dynamic range of innate self-nonself discrimination by NK cells.
authors.affiliation: Department of Immunology, University of Toronto, and Sunnybrook Research Institute, Toronto, ON, Canada.
authors.forename: Christina L
authors.initials: CL
authors.lastname: Kirkham
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Aguilar
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.forename: Miho
authors.initials: M
authors.lastname: Tanaka
authors.forename: Aruz
authors.initials: A
authors.lastname: Mesci
authors.forename: Kuan-Lun
authors.initials: KL
authors.lastname: Chu
authors.forename: Jason H
authors.initials: JH
authors.lastname: Fine
authors.forename: Karen L
authors.initials: KL
authors.lastname: Mossman
authors.forename: Rod
authors.initials: R
authors.lastname: Bremner
authors.forename: David S J
authors.initials: DSJ
authors.lastname: Allan
authors.forename: James R
authors.initials: JR
authors.lastname: Carlyle
mesh_terms: D000818:Animals; D003602:Cytotoxicity, Immunologic; D005347:Fibroblasts / Q000502:physiology*; D006566:Herpesviridae Infections / Q000276:immunology*; D007113:Immunity, Innate; D007370:Interferon Type I / Q000378:metabolism; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit / Q000235:genetics; D007694:Killer Cells, Natural / Q000276:immunology*; D037181:Lectins, C-Type / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018146:Muromegalovirus / Q000276:immunology*; D041681:NIH 3T3 Cells; D055651:NK Cell Lectin-Like Receptor Subfamily B / Q000378:metabolism*; D019899:Paracrine Communication; D011401:Promoter Regions, Genetic / Q000235:genetics; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D050794:STAT1 Transcription Factor / Q000235:genetics*; D050795:STAT2 Transcription Factor / Q000235:genetics
chemical_list: D007370:Interferon Type I; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D037181:Lectins, C-Type; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011971:Receptors, Immunologic; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; C000627237:Clec2d protein, mouse; C527212:Klrb1b protein, mouse; C494080:Stat1 protein, mouse; C494228:Isgf3g protein, mouse
keywords: Clec2d; Clr-b; Interferon; Missing-self recognition; Mouse cytomegalovirus; NKR-P1B; Natural killer cell; Paracrine