title: Identification of the SLAM Adapter Molecule EAT-2 as a Lupus-Susceptibility Gene That Acts through Impaired Negative Regulation of Dendritic Cell Signaling.
abstract: We showed previously that C57BL/6 congenic mice with an introgressed homozygous 70 cM (125.6 Mb) to 100 cM (179.8 Mb) interval on c1 from the lupus-prone New Zealand Black (NZB) mouse develop high titers of antinuclear Abs and severe glomerulonephritis. Using subcongenic mice, we found that a genetic locus in the 88-96 cM region was associated with altered dendritic cell (DC) function and synergized with T cell functional defects to promote expansion of pathogenic proinflammatory T cell subsets. In this article, we show that the promoter region of the NZB gene encoding the SLAM signaling pathway adapter molecule EWS-activated transcript 2 (EAT-2) is polymorphic, which results in an ∼ 70% reduction in EAT-2 in DC. Silencing of the EAT-2 gene in DC that lacked this polymorphism led to increased production of IL-12 and enhanced differentiation of T cells to a Th1 phenotype in T cell-DC cocultures, reproducing the phenotype observed for DC from congenic mice with the NZB c1 70-100 cM interval. SLAM signaling was shown to inhibit production of IL-12 by CD40L-activated DCs. Consistent with a role for EAT-2 in this inhibition, knockdown of EAT-2 resulted in increased production of IL-12 by CD40-stimulated DC. Assessment of downstream signaling following CD40 cross-linking in the presence or absence of SLAM cross-linking revealed that SLAM coengagement blocked activation of p38 MAPK and JNK signaling pathways in DC, which was reversed in DC with the NZB EAT-2 allele. We conclude that EAT-2 negatively regulates cytokine production in DC downstream of SLAM engagement and that a genetic polymorphism that disturbs this process promotes the development of lupus.
authors.affiliation: Arthritis Centre of Excellence, Toronto Western Research Institute, University Health Network, Toronto, Ontario M5T 2S8, Canada; Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada;
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Talaei
authors.affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada;
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: Arthritis Centre of Excellence, Toronto Western Research Institute, University Health Network, Toronto, Ontario M5T 2S8, Canada; Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada;
authors.forename: Kieran
authors.initials: K
authors.lastname: Manion
authors.affiliation: Lunenfeld Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada; Department of Laboratory Medicine and Pathology, University of Toronto, Toronto, Ontario M5S 1A1, Canada; and.
authors.forename: Rod
authors.initials: R
authors.lastname: Bremner
authors.affiliation: Arthritis Centre of Excellence, Toronto Western Research Institute, University Health Network, Toronto, Ontario M5T 2S8, Canada; Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada jwither@uhnres.utoronto.ca.
authors.forename: Joan E
authors.initials: JE
authors.lastname: Wither
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000502:physiology*; D000818:Animals; D000974:Antibodies, Antinuclear / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D023201:CD40 Ligand / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D053765:Interleukin-12 Subunit p35 / Q000096:biosynthesis; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008814:Mice, Inbred NZB; D008969:Molecular Sequence Data; D034622:RNA Interference; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000276:immunology; D018417:Th1 Cells / Q000166:cytology / Q000276:immunology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000974:Antibodies, Antinuclear; C508859:Il12a protein, mouse; D053765:Interleukin-12 Subunit p35; D034741:RNA, Small Interfering; C491225:Sh2d1b1 protein, mouse; D023201:CD40 Ligand; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases