title: ChIP-on-chip analysis identifies IL-22 as direct target gene of ectopically expressed FOXP3 transcription factor in human T cells.
abstract: BACKGROUND
  The transcription factor (TF) forkhead box P3 (FOXP3) is constitutively expressed at high levels in naturally occurring CD4+CD25+ regulatory T cells (nTregs). It is not only the most accepted marker for that cell population but is also considered lineage determinative. Chromatin immunoprecipitation (ChIP) of TFs in combination with genomic tiling microarray analysis (ChIP-on-chip) has been shown to be an appropriate tool for identifying FOXP3 transcription factor binding sites (TFBSs) on a genome-wide scale. In combination with microarray expression analysis, the ChIP-on-chip technique allows identification of direct FOXP3 target genes.
  
  
  RESULTS
  ChIP-on-chip analysis of the human FOXP3 expressed in resting and PMA/ionomycin-stimulated Jurkat T cells revealed several thousand putative FOXP3 binding sites and demonstrated the importance of intronic regions for FOXP3 binding. The analysis of expression data showed that the stimulation-dependent down-regulation of IL-22 was correlated with direct FOXP3 binding in the IL-22 promoter region. This association was confirmed by real-time PCR analysis of ChIP-DNA. The corresponding ChIP-region also contained a matching FOXP3 consensus sequence.
  
  
  CONCLUSIONS
  Knowledge of the general distribution patterns of FOXP3 TFBSs in the human genome under resting and activated conditions will contribute to a better understanding of this TF and its influence on direct target genes, as well as its importance for the phenotype and function of Tregs. Moreover, FOXP3-dependent repression of Th17-related IL-22 may be relevant to an understanding of the phenomenon of Treg/Th17 cell plasticity.
authors.affiliation: Immune Regulation group, Helmholtz Centre for Infection Research, Inhoffenstraße 7, Braunschweig, 38124, Germany. andreas.jeron@med.ovgu.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Jeron
authors.forename: Wiebke
authors.initials: W
authors.lastname: Hansen
authors.forename: Franziska
authors.initials: F
authors.lastname: Ewert
authors.forename: Jan
authors.initials: J
authors.lastname: Buer
authors.forename: Robert
authors.initials: R
authors.lastname: Geffers
authors.forename: Dunja
authors.initials: D
authors.lastname: Bruder
mesh_terms: D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation / Q000379:methods*; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D006801:Humans; D007378:Interleukins / Q000378:metabolism*; D019169:Jurkat Cells; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D060888:Real-Time Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism*; D000097043:Interleukin-22
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D051858:Forkhead Transcription Factors; D007378:Interleukins; D000097043:Interleukin-22; C418974:FOXP3 protein, human