p53 Gene Deficiency Does Not Enhance Instability of Mouse Minisatellites in Somatic Cells of Normal Tissues

The effect of p53‐deficiency on somatic mutation of minisatellites in normal tissues was examined using p53‐deficient (−/−) mice. In total, 248 mice consisting of three different genotypes, +/+, +/− and −/−, were obtained and DNA from their embryos was probed with two minisatellites, Pc‐1 and Pc‐2. The somatic mutation was detected by Southern blot hybridization as the presence of a third nonparental band reflecting mosaicism in tissues. Mutation frequency of Pc‐1 for (+/+) and (+/−) was 1.3% and 1.4%, respectively, which is consistent with previous studies. On the other hand, none of the mice lacking the p53 gene (−/−) exhibited mutation. The Pc‐2 probe did not show any somatic mutation in the three groups. These results suggest that the p53 deficiency does not enhance the genomic instability of the minisatellite loci in normal somatic cells.