Mutation Strain Type
Mice that are homozygous for the targeted Trp53 mutation (i.e. Hupki) are healthy, fertile and do not display any gross abnormalities. The expression and functional activity of the chimeric Trp53 gene in homozygous Hupki mice is normal. Homozygous Hupki mice that are also homozygous for the targeted Xpa knockout mutation (i.e. Xpa-Null) are viable and fertile and do not undergo spontaneous tumour development. (However, the stock was not maintained by homozygous matings, but by mating Xpa<tm1Hvs>/+ to +/+). Xpa is required for nucleotide excision repair (NER), therefore Xpa-Null mice and cells are completely deficient in NER. Hupki:Xpa-Null mice and embryo fibroblasts are highly sensitive to carcinogens that generate DNA damage normally repaired by NER (e.g. bulky DNA adducts) compared with Hupki:Xpa-wild-type controls (unpublished data).