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The p50 subunit of NF-?B orchestrates dendritic cell lifespan and activation of adaptive immunity.

ABSTRACT: Dendritic cells play a central role in keeping the balance between immunity and immune tolerance. A key factor in this equilibrium is the lifespan of DC, as its reduction restrains antigen availability leading to termination of immune responses. Here we show that lipopolysaccharide-driven DC maturation is paralleled by increased nuclear levels of p50 NF-?B, an event associated with DC apoptosis. Lack of p50 in murine DC promoted increased lifespan, enhanced level of maturation associated with increased expression of the proinflammatory cytokines IL-1, IL-18 and IFN-?, enhanced capacity of activating and expanding CD4(+) and CD8(+) T cells in vivo and decreased ability to induce differentiation of FoxP3(+) regulatory T cells. In agreement, vaccination of melanoma-bearing mice with antigen-pulsed LPS-treated p50(-/-) BM-DC boosted antitumor immunity and inhibition of tumor growth. We propose that nuclear accumulation of the p50 NF-?B subunit in DC, as occurring during lipopolysaccharide-driven maturation, is a homeostatic mechanism tuning the balance between uncontrolled activation of adaptive immunity and immune tolerance.

SUBMITTER: Larghi P

PROVIDER: S-EPMC3458114 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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The p50 subunit of NF-κB orchestrates dendritic cell lifespan and activation of adaptive immunity.

Larghi Paola P Porta Chiara C Riboldi Elena E Totaro Maria Grazia MG Carraro Lorenzo L Orabona Ciriana C Sica Antonio A

PloS one 20120925 9

Dendritic cells play a central role in keeping the balance between immunity and immune tolerance. A key factor in this equilibrium is the lifespan of DC, as its reduction restrains antigen availability leading to termination of immune responses. Here we show that lipopolysaccharide-driven DC maturation is paralleled by increased nuclear levels of p50 NF-κB, an event associated with DC apoptosis. Lack of p50 in murine DC promoted increased lifespan, enhanced level of maturation associated with in ...[more]

PMID: 23049782

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Project description:The family of NF-κB transcriptional activators controls the expression of many genes, including those involved in cell survival and development. The family consists of homo- and heterodimers constituted by combinations of five subunits. Subunit p50 includes 13 tyrosine residues, but the relationship between specific tyrosine phosphorylations and p50 function is not well understood. Subunits of p50 and p65 prepared in vitro formed a heterodimer, but this NF-κB would not bind to the interleukin-2 (IL-2) promoter DNA. Treatment of p50 with guanosine triphosphate (GTP) and a lysate from activated Jurkat cells, effected rapid p50 phosphorylation, and, in the presence of wild-type subunit p65, was accompanied on the same time scale by IL-2 promoter DNA binding. Modified p50s containing one of seven stoichiometrically phosphorylated tyrosines in NF-κB p50/p65 heterodimers, included three that facilitated binding to the IL-2 DNA promoter region to a greater extent than the wild type. One of these three stoichiometrically phosphorylated p50/p65 heterodimers of NF-κB, containing pTyr60 in the p50 subunit, was treated with a lysate from activated Jurkat cells + GTP and shown to be phosphorylated on the same time scale as wild-type p50. This modified NF-κB also developed IL-2 promoter DNA binding activity on the same time scale as the wild type but exhibited greater binding to the IL-2 DNA promoters than the wild type. The nature of this enhanced binding was studied in greater detail using a metabolically stable pTyr derivative at position 60 of p50 and cellular phosphatases. We suggest that enhanced DNA binding of modified NF-κB containing pTyr60 in the p50 subunit may reflect stoichiometric NF-κB phosphorylation at a site that is not normally fully phosphorylated, or not phosphorylated at all, and is relatively resistant to the effects of Jurkat cell tyrosine phosphatase activity. This conclusion was reinforced by demonstrating that modification of Tyr60 of p50 with a metabolically stable methylenephosphonate moiety further increased the stability of the formed NF-κB p50/p65 heterodimer against the action of activated Jurkat cell phosphatases.

Dataset Information

The p50 subunit of NF-?B orchestrates dendritic cell lifespan and activation of adaptive immunity.

Publications

The p50 subunit of NF-κB orchestrates dendritic cell lifespan and activation of adaptive immunity.

Similar Datasets

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