0000000000060134
AUTHOR
Stefan Klein-hessling
Nfatc1/Αa and Blimp-1 Support the Follicular and Effector Phenotype of Tregs
CD4 + CXCR5 + Foxp3 + T follicular regulatory (T FR ) cells control the germinal center responses. Like follicular helper T-cells, they express high levels of N uclear F actor of A ctivated T -cells c1 , predominantly its short isoform NFATc1/αA. Ablation of NFATc1 in Tregs prevents upregulation of CXCR5 and migration of T FR cells into B-cell follicles. By contrast, constitutive active NFATc1/αA defines the surface density of CXCR5, whose level determines how deep a T FR migrates into the GC and how effectively it controls antibody production. NFATc1/αA is necessary to overcome T FR -expressed B l ymphocyte- i nduced m aturation p rotein (Blimp-1), which can directly repress Cxcr5. Blimp-1…
Cyclic AMP-induced Chromatin Changes Support the NFATc-mediated Recruitment of GATA-3 to the Interleukin 5 Promoter
Elevated intracellular cyclic AMP levels, which suppress the proliferation of naive T cells and type 1 T helper (Th1) cells are a property of T helper 2 (Th2) cells and regulatory T cells. While cyclic AMP signals interfere with the IL-2 promoter induction, they support the induction of Th2-type genes, in particular of il-5 gene. We show here that cyclic AMP signals support the generation of three inducible DNase I hypersensitive chromatin sites over the il-5 locus, including its promoter region. In addition, cyclic AMP signals enhance histone H3 acetylation at the IL-5 promoter and the concerted binding of GATA-3 and NFATc to the promoter. This is facilitated by direct protein-protein inte…
NFAT transcription factors in control of peripheral T cell tolerance.
The Ca++-regulated calcineurin/NFAT cascade is one of the crucial signalling pathways that controls adaptive immunity. However, a number of novel experimental data suggest that, in addition to their role in T cell activation, NFATc transcription factors play also a decisive role in the generation of peripheral tolerance against self-antigens. This function of NFATc factors is mediated by controlling activation-induced cell death and clonal anergy of T helper cells and the activity of regulatory T cells. The multi-functional role of NFATc proteins characterize these transcription factors as key regulators of immunological tolerance and, if dysregulated, of development of autoimmune diseases.
p38 MAP kinase drives the expression of mast cell-derived IL-9 via activation of the transcription factor GATA-1.
Mast cells are able to produce a huge panel of mediators including the Th2-type cytokine IL-9, which is considered to be a key mediator for the pathogenesis of allergic asthma, but detailed information on the regulation of IL-9 transcription in mast cells has been scarce. Herein we provide evidence that the erythroid/myeloid transcription factor GATA-1, which is not expressed in Th2 cells, is a potent activator of IL-9 expression in murine bone marrow-derived mast cells (BMMC). Furthermore, in mast cells, but not in Th2 cells, production of IL-9 is sensitive to inhibition of p38 MAP kinase. As transactivation mediated by GATA-1 is also sensitive to inhibition of p38 MAP kinase, and GATA-1 i…
NFATc1 affects mouse splenic B cell function by controlling the calcineurin–NFAT signaling network
Mouse B cells lacking NFATc1 exhibit defective proliferation, survival, isotype class switching, cytokine production, and T cell help.
The role of NF-AT transcription factors in T cell activation and differentiation11We dedicate this review to Prof. Dr. Rigomar Rieger (Gatersleben), a great scientist and man, on the occasion of his 70th birthday. One of us (E.S.) had the pleasure of working in his department.
AbstractThe family of genuine NF-AT transcription factors consists of four members (NF-AT1 [or NF-ATp], NF-AT2 [or NF-ATc], NF-AT3 and NF-AT4 [or NF-ATx]) which are characterized by a highly conserved DNA binding domain (is designated as Rel similarity domain) and a calcineurin binding domain. The binding of the Ca2+-dependent phosphatase calcineurin to this region controls the nuclear import and exit of NF-ATs. This review deals (1) with the structure of NF-AT proteins, (2) the DNA binding of NF-AT factors and their interaction with AP-1, (3) NF-AT target genes, (4) signalling pathways leading to NF-AT activation: the role of protein kinases and calcineurin, (5) the nuclear entry and exit …
NFATc1 supports imiquimod-induced skin inflammation by suppressing IL-10 synthesis in B cells
Epicutaneous application of Aldara cream containing the TLR7 agonist imiquimod (IMQ) to mice induces skin inflammation that exhibits many aspects of psoriasis, an inflammatory human skin disease. Here we show that mice depleted of B cells or bearing interleukin (IL)-10-deficient B cells show a fulminant inflammation upon IMQ exposure, whereas ablation of NFATc1 in B cells results in a suppression of Aldara-induced inflammation. In vitro, IMQ induces the proliferation and IL-10 expression by B cells that is blocked by BCR signals inducing NFATc1. By binding to HDAC1, a transcriptional repressor, and to an intronic site of the Il10 gene, NFATc1 suppresses IL-10 expression that dampens the pro…
Epigenetic Control of the foxp3 Locus in Regulatory T Cells
Compelling evidence suggests that the transcription factor Foxp3 acts as a master switch governing the development and function of CD4+ regulatory T cells (Tregs). However, whether transcriptional control of Foxp3 expression itself contributes to the development of a stable Treg lineage has thus far not been investigated. We here identified an evolutionarily conserved region within the foxp3 locus upstream of exon-1 possessing transcriptional activity. Bisulphite sequencing and chromatin immunoprecipitation revealed complete demethylation of CpG motifs as well as histone modifications within the conserved region in ex vivo isolated Foxp3+CD25+CD4+ Tregs, but not in naïve CD25−CD4+ T cells. …
NFATc1 Induction in Peripheral T and B Lymphocytes
Abstract NFAT transcription factors control the proliferation and survival of peripheral lymphocytes. We have reported previously that the short isoform NFATc1/αA whose generation is induced by immune receptor stimulation supports the proliferation and inhibits the activation-induced cell death of peripheral T and B cells. We will show in this study that in novel bacterial artificial chromosome transgenic mice that express EGFP under the control of entire Nfatc1 locus the Nfatc1/Egfp transgene is expressed as early as in double-negative thymocytes and in nonstimulated peripheral T and B cells. Upon immune receptor stimulation, Nfatc1/Egfp expression is elevated in B, Th1, and Th2 cells, but…
IL-9 and IL-13 production by activated mast cells is strongly enhanced in the presence of lipopolysaccharide: NF-kappa B is decisively involved in the expression of IL-9.
Abstract Mast cells, due to their ability to produce a large panel of mediators and cytokines, participate in a variety of processes in adaptive and innate immunity. Herein we report that in primary murine bone marrow-derived mast cells activated with ionomycin or IgE-Ag the bacterial endotoxin LPS strongly enhances the expression of IL-9 and IL-13, but not IL-4. This costimulatory effect of LPS is absent in activated mast cells derived from the LPS-hyporesponsive mouse strain BALB/c-LPSd, although in these cells the proinflammatory cytokine IL-1 can still substitute for LPS. The enhanced production of mast cell-derived IL-13 in the presence of IL-1 is a novel observation. Coactivation of m…
Specific and Redundant Roles for NFAT Transcription Factors in the Expression of Mast Cell-Derived Cytokines
Abstract By virtue of their ability to express a plethora of biologically highly active mediators, mast cells (MC) are involved in both adaptive and innate immune responses. MC-derived Th2-type cytokines are thought to act as local amplifiers of Th2 reactions, including chronic inflammatory disorders such as allergic asthma, whereas MC-derived TNF-α is a critical initiator of antimicrobial defense. In this study, we demonstrate that the transcription factors NFATc1 and NFATc2 are part of a MC-specific signaling network that regulates the expression of TNF-α and IL-13, whereas NFATc3 is dispensable. Primary murine bone marrow-derived MC from NFATc2−/− mice, activated by either ionomycin or I…
Lack of NFATc1 SUMOylation prevents autoimmunity and alloreactivity
A novel transgenic mouse, in which the transcription factor NFATc1 bears lysine-to-arginine mutations that prevent modification by SUMO, develops normally and is healthy. However, SUMO-insensitive NFATc1 transmits strong tolerogenic signals, thus preventing autoimmune and alloimmune T cell responses.
NF-κB factors control the induction of NFATc1 in B lymphocytes
In peripheral lymphocytes, the transcription factors (TFs) NF-κB, NFAT, and AP-1 are the prime targets of signals that emerge from immune receptors. Upon activation, these TFs induce gene networks that orchestrate the growth, expansion, and effector function of peripheral lymphocytes. NFAT and NF-κB factors share several properties, such as a similar mode of induction and architecture in their DNA-binding domain, and there is a subgroup of κB-like DNA promoter motifs that are bound by both types of TFs. However, unlike NFAT and AP-1 factors that interact and collaborate in binding to DNA, NFAT, and NF-κB seem neither to interact nor to collaborate. We show here that NF-κB1/p50 and c-Rel, th…