Regulation of the expression of human C epsilon germline transcript. Identification of a novel IL-4 responsive element.
Transcriptional regulation for Ig H chain germline transcripts induced by cytokines is a topic of recent interest for the understanding of the mechanism of class switch recombination. Among human B cell lines examined, we have found that a human IgM-producing B cell line, DND39 (EBV negative) expressed germ-line transcripts of epsilon constant gene (C epsilon) when stimulated with IL-4. In our study, the regulatory element responsible for the expression of IL-4-induced human C epsilon germ-line transcript was determined using DND39 cells. To identify the IL-4 responsive promoter/enhancer element, deletion analysis of the upstream region of the germ-line exon (I epsilon) of the C epsilon germ-line transcript which is located 5' to the switch region, was performed by using a luciferase gene as a reporter. Deletion analysis showed that a DNA fragment which lies between -215 and -154 bp upstream from the most 3' transcriptional initiation site of human I epsilon gene is fully responsible for the induction of germ-line transcripts by IL-4. According to a mutational analysis, the DNA fragment between -163 and -152 bp, was identified to be a novel IL-4 responsive element in a human C epsilon gene. Electrophoretic gel mobility shift assay showed the presence of IL-4-induced nuclear factor that specifically bound to this IL-4 responsive element. This novel IL-4 responsive element and an IL-4-induced DNA binding protein may play an important role for the induction of C epsilon germ-line transcript as well as class switching to IgE.
Ichiki
T
T
Department of Molecular Immunology, Kyushu University, Fukuoka, Japan.
Takahashi
W
W
Watanabe
T
T
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000502:physiology; D005786:Gene Expression Regulation; D005803:Genes, Immunoglobulin; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics*; D007073:Immunoglobulin E / Q000235:genetics*; D015847:Interleukin-4 / Q000494:pharmacology*; D016393:Lymphoma, B-Cell / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D007127:Immunoglobulin Constant Regions; D012333:RNA, Messenger; D015847:Interleukin-4; D007073:Immunoglobulin E; D013755:Tetradecanoylphorbol Acetate