Host: The Japanese Society of Toxicology
It is well known that somatic mutations are induced by ionizing irradiation. We have previously reported the measurement of mutant frequency on the T-cell receptor (TCR) gene in mouse T-lymphocytes after irradiation by flow cytomery. Recently, the Pig-a mutation assay has been developed to evaluate in vivo genotoxicity in laboratory animals and humans. In this study, we used three-color staining with fluorescently labeled anti-CD24, anti-TER-119, and anti-CD71 to detect the Pig-a mutant frequency in total red blood cells (RBCs) from X-irradiated mice. Single exposures to X-irradiation resulted in dose-dependent increases in Pig-a mutant frequency. We compared Pig-a mutant frequencies between irradiated C57BL/6J (p53+/+) mice and p53-/- mice. After the peak in radiation-induced Pig-a mutant frequencies, a gradual decrease in mutant frequencies in irradiated p53-/- mice was observed, while irradiated p53+/+ mice had a rapid decrease, which suggests that Pig-a mutant cells are eliminated normally in irradiated p53+/+ mice but not in irradiated p53-/- mice due to lack of p53 function. In addition, we also found that the p53 function affected the regulation of Pig-a mutagenesis in aging mice. Our results suggest that p53 function, distinct types of mutation, and the life span of RBCs play key roles in the persistence of Pig-a mutation in the hematopoietic system of RBCs after irradiation.
