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Updated: Oct 5, 2026

Measurements of Physiological Stress Responses in C. Elegans
Published on: May 21, 2020
Regulation of the catalase gene promoter by Sp1, CCAAT-recognizing factors, and a WT1/Egr-related factor in hydrogen
1Radiation Hazards Research Group, National Institute of Radiological Sciences, 9-1, Anagawa-4-chome, Inage-ku, Chiba 263-8555, Japan. m_nenoi@nirs.go.jp
Abstract:
Reactive oxygen species play a critical role in the onset of apoptosis induced by various extracellular stimuli, including ionizing radiation. Therefore active regulation of reactive oxygen species-metabolizing enzymes may be one response to an apoptotic stimulus. In this regard, HP100 cells, H(2)O(2)-resistant variants derived from human leukemia HL60 cells, display an interesting phenotype in which the activity of catalase is constitutively high, whereas its mRNA is reduced after X-ray irradiation. In the present study, we investigated the molecular mechanisms underlying this phenomenon. By combining analyses from nuclear run-on, reporter gene transient transfection, genomic footprinting, site-directed mutagenesis, electrophoretic mobility shift analysis, and Western blotting experiments, we found that constitutively elevated catalase expression is strongly regulated at the transcriptional level by both Sp1 and CCAAT-recognizing factors and that much higher levels of nuclear Sp1 and NF-Y are present in HP100 nuclei as compared with HL60 nuclei. In addition, we demonstrated an X-ray-inducible association of a WT1/Egr-related factor with an overlapping Sp1/Egr-1 recognition sequence located within the core promoter of the catalase gene. This association may lead to inactivation of the promoter by disturbing or competing with the transactivating ability of Sp1.
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