Subject(s)
Th1 Cells/immunology , Th2 Cells/immunology , Transcription, Genetic , Cell Differentiation , Chromatin/physiology , DNA-Binding Proteins/physiology , GATA3 Transcription Factor , Humans , Interferon-gamma/immunology , Interferon-gamma/metabolism , Interleukin-4/immunology , Proto-Oncogene Proteins/physiology , Proto-Oncogene Proteins c-maf , Th1 Cells/cytology , Th2 Cells/cytology , Trans-Activators/physiology , Transcription Factors/metabolismABSTRACT
The critical function of NFAT proteins in maintaining lymphoid homeostasis was revealed in mice lacking both NFATp and NFAT4 (DKO). DKO mice exhibit increased lymphoproliferation, decreased activation-induced cell death, and impaired induction of FasL. The transcription factors Egr2 and Egr3 are potent activators of FasL expression. Here we find that Egr2 and Egr3 are NFAT target genes. Activation of FasL occurs via the NFAT-dependent induction of Egr3, as demonstrated by the ability of exogenously provided NFATp to restore Egr-dependent FasL promoter activity in DKO lymph node cells. Further, Egr3 expression is enriched in Th1 cells, suggesting a molecular basis for the known preferential expression of FasL in the Th1 versus Th2 subset.
Subject(s)
DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Intracellular Signaling Peptides and Proteins , Membrane Glycoproteins/genetics , Transcription Factors/genetics , Transcription Factors/metabolism , Transcriptional Activation , Animals , Binding Sites , Carrier Proteins/genetics , Carrier Proteins/metabolism , Cell Extracts , Cell Nucleus/metabolism , Cells, Cultured , DNA-Binding Proteins/physiology , Early Growth Response Protein 2 , Early Growth Response Protein 3 , Fas Ligand Protein , Female , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Knockout , NFATC Transcription Factors , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Promoter Regions, Genetic , Th1 Cells/cytology , Th1 Cells/metabolism , Th2 Cells/cytology , Th2 Cells/metabolism , Transcription Factors/physiologyABSTRACT
Nuclear factor of activated T cells (NFAT) is a critical regulator of early gene transcription in response to TCR-mediated signals. Here, we show that mice lacking both NFATp and NFAT4 develop a profound lymphoproliferative disorder likely due to a lowered threshold for TCR signaling coupled with increased resistance to apoptosis secondary to defective FasL expression. NFAT mutant mice also have allergic blepharitis, interstitial pneumonitis, and a 10(3) to 10(4) fold increase in serum IgG1 and IgE levels, secondary to a dramatic and selective increase in Th2 cytokines. This phenotype may be ascribed to unopposed occupancy of the IL-4 promoter by NFATc. Our data demonstrate that lymphoid homeostasis and Th2 activation require a critical balance among NFAT family members.
Subject(s)
DNA-Binding Proteins/physiology , Homeostasis/physiology , Lymphoid Tissue/physiology , Nuclear Proteins , Th2 Cells/physiology , Transcription Factors/physiology , Alveolitis, Extrinsic Allergic/immunology , Alveolitis, Extrinsic Allergic/metabolism , Animals , Apoptosis/physiology , B-Lymphocytes/immunology , B-Lymphocytes/metabolism , B-Lymphocytes/physiology , Blepharitis/immunology , Blepharitis/metabolism , Cell Nucleus/metabolism , Cytokines/biosynthesis , DNA-Binding Proteins/biosynthesis , Fas Ligand Protein , Immunoglobulins/biosynthesis , Lung Diseases, Interstitial/immunology , Lung Diseases, Interstitial/metabolism , Lymphocyte Activation/physiology , Lymphoid Tissue/cytology , Lymphoid Tissue/immunology , Membrane Glycoproteins/biosynthesis , Mice , Mice, Inbred BALB C , NFATC Transcription Factors , Receptors, Antigen, T-Cell/physiology , Signal Transduction/physiology , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , T-Lymphocytes/physiology , Th2 Cells/immunology , Th2 Cells/metabolism , Transcription Factors/biosynthesisABSTRACT
The induction of cytokine gene transcription is mediated in part by the nuclear factor of activated T cells (NF-AT). Factors involved in the mechanisms of NF-AT-mediated transcription are not well understood. A nuclear factor that interacted with the Rel homology domain (RHD) of NF-ATp was identified with the use of a two-hybrid interaction trap. Designated NIP45 (NF-AT interacting protein), it has minimal similarity to any known genes. Transcripts encoding this factor were enriched in lymphoid tissues and testes. NIP45 synergized with NF-ATp and the proto-oncogene c-Maf to activate the interleukin-4 (IL-4) cytokine promoter; transient overexpression of NIP45 with NF-ATp and c-maf in B lymphoma cells induced measurable endogenous IL-4 protein production. The identification of NIP45 advances our understanding of gene activation of cytokines, critical mediators of the immune response.
