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IFN-? suppresses GATA3 transcription from a distal exon and promotes H3K27 trimethylation of the CNS-1 enhancer in human Th2 cells.

ABSTRACT: CD4(+) Th2 development is regulated by the zinc finger transcription factor GATA3. Once induced by acute priming signals, such as IL-4, GATA3 poises the Th2 cytokine locus for rapid activation and establishes a positive-feedback loop that maintains elevated GATA3 expression. Type I IFN (IFN-?/?) inhibits Th2 cells by blocking the expression of GATA3 during Th2 development and in fully committed Th2 cells. In this study, we uncovered a unique mechanism by which IFN-?/? signaling represses the GATA3 gene in human Th2 cells. IFN-?/? suppressed expression of GATA3 mRNA that was transcribed from an alternative distal upstream exon (1A). This suppression was not mediated through DNA methylation, but rather by histone modifications localized to a conserved noncoding sequence (CNS-1) upstream of exon 1A. IFN-?/? treatment led to a closed conformation of CNS-1, as assessed by DNase I hypersensitivity, along with enhanced accumulation of H3K27me3 mark at this CNS region, which correlated with increased density of total nucleosomes at this putative enhancer. Consequently, accessibility of CNS-1 to GATA3 DNA binding activity was reduced in response to IFN-?/? signaling, even in the presence of IL-4. Thus, IFN-?/? disrupts the GATA3-autoactivation loop and promotes epigenetic silencing of a Th2-specific regulatory region within the GATA3 gene.

SUBMITTER: Huber JP

PROVIDER: S-EPMC4104489 | biostudies-other | 2014 Jun

REPOSITORIES: biostudies-other

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IFN-α suppresses GATA3 transcription from a distal exon and promotes H3K27 trimethylation of the CNS-1 enhancer in human Th2 cells.

Huber Jonathan P JP Gonzales-van Horn Sarah R SR Roybal Kole T KT Gill Michelle A MA Farrar J David JD

Journal of immunology (Baltimore, Md. : 1950) 20140509 12

CD4(+) Th2 development is regulated by the zinc finger transcription factor GATA3. Once induced by acute priming signals, such as IL-4, GATA3 poises the Th2 cytokine locus for rapid activation and establishes a positive-feedback loop that maintains elevated GATA3 expression. Type I IFN (IFN-α/β) inhibits Th2 cells by blocking the expression of GATA3 during Th2 development and in fully committed Th2 cells. In this study, we uncovered a unique mechanism by which IFN-α/β signaling represses the GAT ...[more]

PMID: 24813204

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Project description:The transcription factor PU.1 is predominantly expressed in dendritic cells (DCs) and is essential for DC differentiation. Although there are several reports that PU.1 positively regulates the expression of DC-specific genes, whether PU.1 also has a suppressive effect on DCs is largely unknown. Here we demonstrate that PU.1 suppresses the expression of Th2 cytokines including IL-13 and IL-5 in bone marrow-derived DCs (BMDCs), through repression of the expression of GATA3, which is a master regulator of Th2 differentiations. When PU.1 siRNA was introduced into BMDCs, LPS-induced expression of IL-13 and IL-5 was increased along with upregulation of the constitutive expression of GATA2 and GATA3. The additional introduction of GATA3 siRNA but not of GATA2 siRNA abrogated PU.1 siRNA-mediated upregulation of IL-13 and IL-5. A chromatin immunoprecipitation assay showed that PU.1 bound to Gata3 proximal promoter region, which is more dominant than the distal promoter in driving GATA3 transcription in DCs. The degree of histone acetylation at the Gata3 promoter was decreased in PU.1 siRNA-introduced DCs, suggesting the involvement of PU.1 in chromatin modification of the Gata3 promoter. Treatment with a histone deacetylase (HDAC) inhibitor, trichostatin A, increased the degree of histone H3 acetylation at the Gata3 promoter and induced the subsequent expression of GATA3. Experiments using HDAC inhibitors and siRNAs showed that HDAC3 suppressed GATA3 expression. The recruitment of HDAC3 to the Gata3 promoter was decreased by PU.1 knockdown. LPS-induced IL-13 expression was dramatically reduced in BMDCs generated from mice lacking the conserved GATA3 response element, termed CGRE, which is an essential site for the binding of GATA3 on the Il-13 promoter. The degree of H3K4me3 at CGRE was significantly increased in PU.1 siRNA-transfected stimulated DCs. Our results indicate that PU.1 plays pivotal roles in DC development and function, serving not only as a transcriptional activator but also as a repressor.

Dataset Information

IFN-? suppresses GATA3 transcription from a distal exon and promotes H3K27 trimethylation of the CNS-1 enhancer in human Th2 cells.

Publications

IFN-α suppresses GATA3 transcription from a distal exon and promotes H3K27 trimethylation of the CNS-1 enhancer in human Th2 cells.

Similar Datasets

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