title: Stat6 inhibits human interleukin-4 promoter activity in T cells.
abstract: The differentiation of naive T-helper (Th) cells into cytokine-secreting effector Th cells requires exposure to multiple signals, including exogenous cytokines. Interleukin-4 (IL-4) plays a major role in this process by promoting the differentiation of IL-4-secreting Th2 cells. In Th2 cells, IL-4 gene expression is tightly controlled at the level of transcription by the coordinated binding of multiple transcription factors to regulatory elements in the proximal promoter region. Nuclear factor of activated T cell (NFAT) family members play a critical role in regulating IL-4 transcription and interact with up to five sequences (termed P0 through P4) in the IL-4 promoter. The molecular mechanisms by which IL-4 induces expression of the IL-4 gene are not known, although the IL-4-activated transcription factor signal transducer and activator of transcription 6 (Stat6) is required for this effect. We report here that Stat6 interacts with three binding sites in the human IL-4 promoter by electrophoretic mobility shift assays. These sites overlap the P1, P2, and P4 NFAT elements. To investigate the role of Stat6 in regulating IL-4 transcription, we used Stat6-deficient Jurkat T cells with different intact IL-4 promoter constructs in cotransfection assays. We show that, whereas a multimerized response element from the germline IgE promoter was highly induced by IL-4 in Stat6-expressing Jurkat cells, the intact human IL-4 promoter was repressed under similar conditions. We conclude that the function of Stat6 is highly dependent on promoter context and that this factor promotes IL-4 gene expression in an indirect manner.
authors.affiliation: Divisions of Pulmonary and Critical Care Medicine and Allergy and Clinical Immunology, The Johns Hopkins University Asthma and Allergy Center, Baltimore, MD, USA. sgeoras@welchlink.welch.jhu.edu
authors.forename: S N
authors.initials: SN
authors.lastname: Georas
authors.forename: J E
authors.initials: JE
authors.lastname: Cumberland
authors.forename: T F
authors.initials: TF
authors.lastname: Burke
authors.forename: R
authors.initials: R
authors.lastname: Chen
authors.forename: U
authors.initials: U
authors.lastname: Schindler
authors.forename: V
authors.initials: V
authors.lastname: Casolaro
mesh_terms: D001665:Binding Sites / Q000235:genetics; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D015847:Interleukin-4 / Q000235:genetics* / Q000494:pharmacology; D019169:Jurkat Cells; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D019948:Receptors, Interleukin-4 / Q000502:physiology; D050800:STAT6 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D019948:Receptors, Interleukin-4; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D015847:Interleukin-4; D015500:Chloramphenicol O-Acetyltransferase