In these p53LSL-25,26,53,54 mice both transactivation domains can be inactivated; expression of the mutant TRP53 protein is silenced until Cre recombinase mediates excision of the upstream floxed STOP cassette. These mice may be useful in studies of p53 function and the role of p53 as a transcriptional activator in tumor suppression.
Laura Attardi, Stanford University Medical Center
The Trp53, transformation related protein 53, gene encodes the p53 tumor suppressor protein, which functions as a transcription factor regulating expression of more than 100 target genes. Mutations resulting in inactivation of p53 protein facilitates tumor progression. These p53LSL-25,26,53,54 mice carry point mutations that result in the amino acid substitutions L25Q and W26S in exon 2, which encodes the first transcriptional activation domain of the protein, F53Q;F54S point mutation in exon 4, in the second transcriptional activation domain and a floxed STOP cassette upstream of exon 2. Expression of the mutant TRP53 protein is silenced until Cre recombinase mediates excision of the floxed STOP cassette. After Cre recombinase mediated removal of the floxed STOP cassette cells from the resulting mice express p53 protein with both transactivation domains inactivated, which cannot activate p53 target genes. Mice carrying the recombined allele exhibit defective cell cycle arrest or apoptosis activity in response to acute DNA damage and fail to suppress tumor development. When bred to Cre recombinase expressing mice, these mice could be used to generate tumor cells for engraftment experiments. Mice that are homozygous for the targeted mutation are viable, but have decreased fertility.
For example, when bred to B6.129-Gt(ROSA)26Sortm1(cre/ERT2)Tyj/J mice (Stock No. 008463) tamoxifen induced Cre recombinase expression in offspring reduces apoptosis following radiation treatment.
A targeting vector designed by Dr. Laura D. Attardi (Stanford University School of Medicine) containing a floxed STOP element with 4 poly adenylation sites, and a puromycin resistance cassette, was utilized to insert the floxed STOP cassette upstream of exon 2, the L25Q and W26S mutations into exon 2, and the F53Q;F54S point mutations into exon 4. The construct was electroporated into 129S4/SvJae-derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were crossed to 129 Sv/J mice.
Upon arrival at The Jackson Laboratory, the mice were crossed to 129S1/SvImJ (Stock No. 002448) at least once to establish the colony.
|Allele Name||targeted mutation 4, Laura D Attardi|
|Allele Type||Targeted (Conditional ready (e.g. floxed), No functional change)|
|Gene Symbol and Name||Trp53, transformation related protein 53|
|Strain of Origin||129S4/SvJae|
|Molecular Note||A floxed puromycin/transcription stop cassette was inserted upstream of exon 2. In addition,mutations were inserted in exon 2 altering the codons for amino acid 25 from leucine to glutamine and amino acid 26 from tryptophan to serine. Further changes in exon 4 altered codon 53 from phenylalanine to glutamine and codon 54 from phenylalanine to serine. Both transactivation domains are incapacitated once the stop sequences are removed by cre expression.|
When maintaining a live colony, these mice can be bred as heterozygotes. Homozygotes exhibit decreased fertility.
When using the p53LSL-25,26,53,54 mouse strain in a publication, please cite the originating article(s) and include JAX stock #021984 in your Materials and Methods section.