NFκB induces overexpression of bovine FcRn: a novel mechanism that further contributes to the enhanced immune response in genetically modified animals carrying extra copies of FcRn.
Among the many functions of the neonatal Fc receptor (FcRn) for IgG, it binds to IgG-opsonized antigen complexes and propagates their traffic into lysosomes where antigen processing occurs. We previously reported that transgenic (Tg) mice and rabbits that carry multiple copies and overexpress FcRn have augmented humoral immune responses. Nuclear factor-kappa B (NFκB) is a critical molecule in the signaling cascade in the immune response. NFκB induces human FcRn expression and our previous in silico analysis suggested NFκB binding sites in the promoter region of the bovine (b) FcRn α-chain gene (FCGRT). Here, we report the identification of three NFκB transcription binding sites in the promoter region of this gene using luciferase reporter gene technology, electromobility shift assay and supershift analysis. Stimulation of primary bovine endothelial cells with the Toll-like receptor-4 ligand lipopolysaccharide (LPS), which mediates its effect via NFκB, resulted in rapid upregulation of the bFcRn expression and a control gene, bovine E-selectin. This rapid bFcRn gene induction was also observed in the spleen of bFcRn Tg mice treated with intraperitoneally injected LPS, analyzed by northern blot analysis. Finally, NFκB-mediated bFcRn upregulation was confirmed at the protein level in macrophages isolated from the bFcRn Tg mice using flow cytometry with a newly developed FcRn specific monoclonal antibody that does not cross-react with the mouse FcRn. We conclude that NFκB regulates bFcRn expression and thus optimizes its functions, e.g., in the professional antigen presenting cells, and contributes to the much augmented humoral immune response in the bFcRn Tg mice.
ImmunoGenes Kft; Budakeszi, Hungary.
Judit
J
Cervenak
Molecular Medicine Research Group; Hungarian Academy of Sciences and Semmelweis University; Budapest, Hungary.
Márton
M
Doleschall
ImmunoGenes Kft; Budakeszi, Hungary.
Balázs
B
Bender
Department of Dermatology, Venereology, and Dermatooncology; Semmelweis University; Budapest, Hungary.
Balázs
B
Mayer
Department of Immunology; Eötvös Loránd University; Budapest, Hungary.
Zita
Z
Schneider
Department of Pathogenetics; National Institute of Oncology; Budapest, Hungary.
Zoltán
Z
Doleschall
State Key Laboratory of Agrobiotechnology; China Agricultural University; Beijing, China.
Yaofeng
Y
Zhao
Agricultural Biotechnology Center; Gödöllő, Hungary.
Zsuzsanna
Z
Bősze
Division of Clinical Immunology; Department of Laboratory Medicine; Karolinska Institute at Karolinska University Hospital Huddinge; Stockholm, Sweden.
Lennart
L
Hammarström
ImmunoGenes Kft; Budakeszi, Hungary.
Wolfgang
W
Oster
ImmunoGenes Kft; Budakeszi, Hungary; Department of Immunology; Eötvös Loránd University; Budapest, Hungary.
Imre
I
Kacskovics
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified / Q000276:immunology; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011961:Receptors, Fc / Q000235:genetics* / Q000276:immunology*; D013154:Spleen / Q000187:drug effects
D000276:Adjuvants, Immunologic; D015395:Histocompatibility Antigens Class I; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011961:Receptors, Fc; C100688:Fc receptor, neonatal
FcRn; IgG; NFκB; antigen presentation; humoral; immune response; transgenic mouse