Ionizing radiation induces, via generation of reactive oxygen intermediates, intercellular adhesion molecule-1 (ICAM-1) gene transcription and NF kappa B-like binding activity in the ICAM-1 transcriptional regulatory region.
Ionizing radiation produces reactive oxygen intermediates in mammalian tissues and may serve as a model system for the investigation of the biologic effects of free radicals. We have previously shown that the adhesion molecule ICAM-1 is induced by ionizing radiation, and here we have investigated the molecular mechanisms responsible. ICAM-1 mRNA and cell surface expression was induced in HeLa and HaCaT cells after exposure to ionizing radiation. This induction was blocked by preincubation with the antioxidants PDTC and N-acetyl cysteine. ICAM-1 promoter activity was assessed by transiently transfecting HeLa cells with CAT-reporter gene constructs containing sequential ICAM-1 5' deletions. ICAM-1 5' fragments -1162/+1 (relative to the transcription start site) and -277/+1 displayed increased promoter activity when cells were exposed to ionizing radiation, but no induction was seen in a -182/+1 construct associating positions -277 to around -182 with inducibility by ionizing radiation. Nuclear extracts from HaCaT cells were tested in mobility shift assays using an NF kappa B-like binding site of the ICAM-1 5' region (positions -186/-177). There was marked enhancement of DNA-protein complex forming in extracts from irradiated versus untreated cells. Incubation of cells with antioxidants prior to irradiation prevented the radiation-dependent increase in complex formation. We conclude that reactive oxygen intermediates are involved in ICAM-1 induction by ionizing radiation. The ionizing radiation-induced, antioxidant-inhibitable binding at the ICAM-1 NF kappa B-like binding site is consistent with the view that NF kappa B is a pro-oxidant transcription factor.
Baeuml
H
H
Department of Dermatology, Ludwig-Maximilians-University, München, Germany.
Behrends
U
U
Peter
R U
RU
Mueller
S
S
Kammerbauer
C
C
Caughman
S W
SW
Degitz
K
K
D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival / Q000528:radiation effects; D002588:Cesium Radioisotopes; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D005091:Exons; D006367:HeLa Cells; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis* / Q000235:genetics*; D016328:NF-kappa B / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid / Q000528:radiation effects*; D016385:TATA Box; D014158:Transcription, Genetic / Q000528:radiation effects*; D014162:Transfection
D002588:Cesium Radioisotopes; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D018799:Intercellular Adhesion Molecule-1; D015500:Chloramphenicol O-Acetyltransferase