title: An intron transcriptional enhancer element regulates IL-4 gene locus accessibility in mast cells.
abstract: The cell type-specific expression of a gene is dependent on developmentally regulated modifications in chromatin structure that allow accessibility of basal and inducible transcription factors. In this study, we demonstrate that a cis-acting element in the second intron of the murine IL-4 gene has a dual function in regulating transcription in mast cells as well as chromatin accessibility of the IL-4 gene locus through its influence on the methylation state of the gene. Previous studies have shown that mast cell-restricted transcription factors GATA-1/2 and PU.1 associate with the intron element and regulate its activity. In this study, we use DNase I footprinting and mutational analyses to identify two additional sites that contribute to the element's ability to enhance transcription. One of these sites associates preferentially with STAT5a and STAT5b. We also demonstrate that deletion of the element or mutation of the GATA binding site in the context of a stably integrated IL-4 genomic construct prevents maintenance of a demethylated locus in IL-4-producing mast cells. These data indicate that, analogous to Ig and TCR intron regulatory elements, the intron enhancer has an essential role in maintaining developmentally regulated demethylation at the IL-4 gene locus. In addition, they indicate that members of the GATA family of transcription factors likely play an important role in these processes.
authors.affiliation: Graduate Program in Immunology and Molecular Pathogenesis, Emory University, Atlanta, GA 30322, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Hural
authors.forename: M
authors.initials: M
authors.lastname: Kwan
authors.forename: G
authors.initials: G
authors.lastname: Henkel
authors.forename: M B
authors.initials: MB
authors.lastname: Hock
authors.forename: M A
authors.initials: MA
authors.lastname: Brown
mesh_terms: D000818:Animals; D000941:Antigens / Q000096:biosynthesis; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D018983:DNA Footprinting; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004742:Enhancer Elements, Genetic / Q000276:immunology / Q000502:physiology*; D005819:Genetic Markers / Q000276:immunology; D015847:Interleukin-4 / Q000235:genetics* / Q000378:metabolism; D007438:Introns / Q000276:immunology / Q000502:physiology*; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D015534:Trans-Activators; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology / Q000502:physiology
chemical_list: D000941:Antigens; D004268:DNA-Binding Proteins; D005819:Genetic Markers; D015847:Interleukin-4; D015534:Trans-Activators; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C494185:Pou1f1 protein, mouse