Abstract
In p53(+/+) mice, which were received a whole-body dose of 3 Gy X-rays at 8 weeks of age, T-cell receptor (TCR) mutation frequencies (MFs) increased to the maximum level 9 days after irradiation. The TCR MFs decreased to background levels at 16 weeks and 20 weeks of age, delayed TCR MF in irradiated mice increased from 60 weeks of age compared to that in non-irradiated mice. In p53(+/-) mice, delayed TCR MF in irradiated mice increased significantly compared to that in non-irradiated mice at 40 weeks of age. We suggested that the p53 gene plays a key role in the regulation of ionizing radiation-induced somatic mutation (Igari, K., et. al., Radiat Res, 166:55-60, 2006). We previously in the last meeting showed the reduction of apoptosis frequency and the expression of phospho-p53 at 72 weeks of age in p53(+/+) mice. We suggested that the rise in TCR MF in delayed mutation is caused by decreased Trp53-dependent apoptosis activity. Also, we showed the rise in translocation frequency in 11th chromosome. We speculated the p53 genome was mutated. We tried to detect p53 genomic mutations at 72 weeks of age in irradiated p53(+/+) mice, we extracted DNA from whole spleen, and then made PCR product in exon 4, 5-6, 7 and 8-9 of p53. However, we could not detect any mutation. In this study, we report how to select CD3-CD4+ cell from spleen cells and sequencing of the p53 genome in CD3-CD4+ cell, because CD3-CD4+ cell is the target cell in TCR MFs.
