The Radiation responsive promoter of the gene

Oba, Hirofumi*; Sato, Katsuya*; Yanagisawa, Tadashi*; Narumi, Issei

Three transcriptional start points for the were located at positions -156, -154 and -22 upstream from the translation initiation site. The amount of the three extended products increased in cells exposed to 2-kGy followed by a 0.5-h post-incubation, suggesting the existence of at least two radiation responsive promoters for expression. A luciferase reporter assay revealed that the distal promoter is located between positions -208 and -156 from the translation initiation site, while the proximal promoter is located between positions -57 and -22. The region located between positions -57 and -38 was indispensable for proximal promoter activity. Site-directed mutagenesis of a thymine positioned at -33 resulted in severe impairment of promoter activity, and suggested that the thymine functions as a master base for the proximal radiation responsive promoter. The results also suggested that up-regulation of expression by the gene product is triggered at the promoter level.