title: MAPK kinase 3 specifically regulates Fc epsilonRI-mediated IL-4 production by mast cells.
abstract: Mast cells play a central role in allergic inflammation and are activated through cross-linking of FcεRI receptor-bound IgE, initiating a signaling cascade resulting in production of biologically potent mediators. Signaling pathways in the regulation of specific mediators remain incompletely defined. In this study, we examined the role of MAPK kinase 3 (MKK3) in IgE-dependent mast cell activation. In an in vivo model of passive cutaneous anaphylaxis, MKK3-deficient mice showed a deficit in late-phase IgE-dependent inflammation. To characterize the mechanism of this deficiency, we cultured bone marrow-derived mast cells (BMMCs) from wild-type and MKK3-deficient mice. We found that FcεRI-mediated mast cell activation induced rapid MKK3 phosphorylation by 5 min, diminishing slowly after 6 h. In MKK3-deficient BMMCs, phosphorylation of p38 was reduced at early and later time points. Among 40 cytokines tested using a protein array, IL-4 was the only cytokine specifically downregulated in MKK3-deficient BMMCs. Reduced IL-4 expression was seen in the local skin of MKK3-deficient mice following passive cutaneous allergic reaction. Furthermore, early growth response-1 (Egr1) bound to the promoter of IL-4 in FcεRI-activated mast cells, and Egr1 transcription factor activity was diminished in MKK3-deficient BMMCs. Finally, mast cell-deficient mice reconstituted with MKK3-deficient BMMCs displayed a significantly impaired late-phase allergic inflammatory response. Thus, mast cell MKK3 signaling contributes to IgE-dependent allergic inflammation and is a specific regulator of FcεRI-induced IL-4 production.
authors.affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia B3K 6R8, Canada.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: MacNeil
authors.forename: Yong Jun
authors.initials: YJ
authors.lastname: Yang
authors.forename: Tong-Jun
authors.initials: TJ
authors.lastname: Lin
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015550:Cell Degranulation / Q000276:immunology; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006967:Hypersensitivity / Q000276:immunology / Q000378:metabolism; D007150:Immunohistochemistry; D015847:Interleukin-4 / Q000096:biosynthesis* / Q000276:immunology; D048371:MAP Kinase Kinase 3 / Q000276:immunology* / Q000378:metabolism; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010323:Passive Cutaneous Anaphylaxis / Q000276:immunology; D040081:Protein Array Analysis; D017455:Receptors, IgE / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*
chemical_list: D017455:Receptors, IgE; D015847:Interleukin-4; D048371:MAP Kinase Kinase 3