Transcriptional regulation of the human IL5 gene by ionizing radiation in Jurkat T cells: evidence for repression by an NF-AT-like element.
Eosinophilia is often observed in patients with parasitic infections and atopic diseases like allergic asthma and atopic dermatitis. Additionally, it is a typical feature of the inflammatory reaction after therapeutic and accidental exposure to ionizing radiation. This uniquely specific phenomenon regulated by the cytokine interleukin 5 (IL-5) suggests specific control for IL5 gene expression. In this study, we generated promoter-CAT constructs containing different human IL-5 promoter regions spanning from positions -507 to +43. Transfection experiments in Jurkat T cells revealed that the promoter sequence from -57 to +43 was required for constitutive and inducible IL-5 promoter activity. Low baseline CAT activity could be enhanced by treatment with phenylmercuric acetate (PMA) or the combination of PMA and calcium ionophore. The promoter region between positions -97 and +43 showed responsiveness to low-dose X rays. Electrophoretic mobility shift assays demonstrated that the region from -117 to -97 was responsive to irradiation. Transcription factors specifically bound to this sequence showed a dose-dependent response to single doses of X rays between 1 and 8 Gy. Competition analysis indicated that the protein-DNA complexes at this region were related to the nuclear factor of activated T cells (NF-AT). Further confirmation was obtained by the addition of specific antibodies into protein-DNA reactions. For the first time, we have demonstrated that specific DNA binding of NF-ATp at the promoter region from -117 to -97 is involved in transcriptional regulation of the human IL5 gene in response to ionizing radiation.
Lu-Hesselmann
J
J
Department of Dermatology, Ludwig-Maximilians-University of Munich, Germany.
Messer
G
G
van Beuningen
D
D
Kind
P
P
Peter
R U
RU
D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D015848:Interleukin-5 / Q000235:genetics*; D019169:Jurkat Cells; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000528:radiation effects*
D004268:DNA-Binding Proteins; D015848:Interleukin-5; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D014157:Transcription Factors; D004247:DNA; D013755:Tetradecanoylphorbol Acetate