Characterization of an interleukin 4 (IL-4) responsive region in the immunoglobulin heavy chain germline epsilon promoter: regulation by NF-IL-4, a C/EBP family member and NF-kappa B/p50.
A large body of data indicate that antibody class switching is directed by cytokines by inducing or repressing transcription from unrearranged, or germline, CH genes. Interleukin 4 (IL-4) induces transcription of the germline C epsilon genes in activated B cells and subsequently, cells in this population will undergo switch recombination to immunoglobulin E. Furthermore, the data suggest that transcription of germline C epsilon genes is required for class switching. In this paper we define DNA elements required for induction of transcription of the germline C epsilon genes by IL-4. To do this, segments of DNA from the 5' flank of the initiation sites for germline epsilon RNA were ligated to a luciferase reporter gene and transfected into two mouse B cell lines, one of which can be induced to switch to IgE. By analysis of a series of 5' deletion constructs and linker-scanning mutations, we demonstrate that a 46-bp segment (residing at -126/-79 relative to the first RNA initiation site) contains an IL-4 responsive region. By electrophoretic mobility shift assays, we find that this segment binds three transcription factors: the recently described NF-IL4, one or more members of the C/EBP family of transcription factors, and NF-kappa B/p50. Mutation of any of the binding sites for these three factors abolishes or reduces IL-4 inducibility of the epsilon promoter. A 27-bp segment within this IL-4 response region containing binding sites for NF-IL4 and a C/EBP factor is sufficient to transfer IL-4 inducibility to a minimal c-fos promoter.
Delphin
S
S
Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester 01655-0122.
Stavnezer
J
J
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D005803:Genes, Immunoglobulin; D006801:Humans; D007139:Immunoglobulin epsilon-Chains / Q000235:genetics*; D015847:Interleukin-4 / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007139:Immunoglobulin epsilon-Chains; C087516:NF-IL4 protein, human; D016328:NF-kappa B; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D015847:Interleukin-4