129S/Sv-Kras^tm4Tyj/J

Stock number: 008180
Research areas: Cancer Research, Developmental Biology Research, Research Tools

Description

This strain carries a point mutation (G12D) in the Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) gene whose expression is blocked by the presence of a loxP-flanked stop codon. Homozygotes die in utero. Cre-mediated recombination can excise the stop codon and permit the oncogenic protein to be expressed. Intranasal infection with an adenovirus encoding Cre results in a very high frequency of lung tumors and permits controlled timing of tumor initiation and tumor multiplicity. This strain may be useful in studies of cancer and development.

Detailed description

This strain carries a point mutation (G12D) whose expression is blocked by the presence of a loxP-flanked stop codon. Homozygotes die in utero. Cre-mediated recombination can excise the stop codon and permit the oncogenic protein to be expressed. Intranasal infection with an adenovirus encoding Cre results in a very high frequency of lung tumors and permits controlled timing of tumor initiation and tumor multiplicity. This strain may be useful in studies of cancer and development.

When bred to a strain expressing Cre recombinase under the control of a tetracycline-responsive promoter element and a strain expressing a tetracycline-controlled activator protein in lung epithelial cells (see Stock No. 006234 and 006235 respectively), this mutant mouse strain may be useful in studies of lung development.

When bred to a strain expressing Cre recombinase in the male germ line (see Stock No. 003328, 007252 for example), this mutant mouse strain may be useful in studies of embryonic development.

When bred to a strain expressing interferon inducible Cre recombinase (see Stock No. 003556, 005673 for example), this mutant mouse strain may be useful in studies of Ras and myeloproliferative disease.

When bred to a strain expressing Cre recombinase in mammary gland, skin, and other secretory glands (see Stock No. 003553 for example), this mutant mouse strain may be useful in studies of epithelial hyperplasias.

When bred to a strain expressing Cre recombinase in epiblast derived tissues (see Stock No. 003755 for example), this mutant mouse strain may be useful in studies of Ras and embryonic development.

When bred to a strain expressing tamoxifen inducible Cre recombinase (see Stock No. 008463 for example), this mutant mouse strain may be useful in studies of tumorigenesis in the colon.

When bred to a strain expressing tamoxifen-inducible Cre recombinase in melanocytes (see Stock No. 012328 for example), this mutant mouse strain may be useful in studies of melanomagenesis.

When bred to a strain expressing Cre recombinase in astrocytes (see Stock No. 012887 for example), this mutant mouse strain may be useful in studies of neurofibroma development.

Development

A targeting vector was designed to place a G12D point mutation in exon 1 of the gene and a loxP-flanked STOP element upstream of the mutation. The STOP element incorporates a PGK-puromycin selection cassette at the 5' end in an opposite directional orientation. An adenoviral strong splice acceptor, typically used in gene trap vectors, is fused upstream of the his3 stuffer fragment to prevent splicing around the stopper (in the case that transcription isn't completely silenced). A mutant splice donor site is on the 3' end and a tetrameric tandem array of SV40 PolyA. The stopper was designed to fit into genomic Sal1 or Xho1 sites. The stop cassette prevents the expression of mutant Kras until it is removed by Cre mediated recombination of the loxP sites, thus allowing expression of oncogenic Kras. The construct was electroporated into 129S4/SvJae-derived J1 embryonic stem (ES) cells. This strain was crossed to 129S4/SvJae for more than 10 generations by the donating laboratory which verified correct orientation by Southern assays involving 5' and 3' external and internal probes.

Allele

Symbol: Kras^tm4Tyj
Name: targeted mutation 4, Tyler Jacks
MGI accession ID: MGI:2429948
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Kras
Marker name: Kirsten rat sarcoma viral oncogene homolog
Chromosome: 6
Strain of origin: 129S4/SvJae
Site of expression: Cre-inducible expression of oncogenic Kras^G12D protein
Molecular note: By homologous recombination in ES cells, the Kras2 locus was targeted with a cassette containing an oncogenic form of the KRAS2 protein in which the glycine at position 12 had been substituted with a an aspartic acid. A loxP flanked stop codon was included upstream of the inserted Kras2 sequence, such that the mutant transcript would be expressed only after cre-mediated recombination.