This LSL-KrasG12D 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.
Terry Van Dyke, NIH
Genetic Background | Generation |
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Allele Type | Gene Symbol | Gene Name |
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Targeted (Conditional ready (e.g. floxed), No functional change) | Kras | Kirsten rat sarcoma viral oncogene homolog |
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.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
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. The mice were backcrossed to C57BL/6 for approximately 15 generations (NCI) and then backcrossed to C57BL/6NCr for 19 generations. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6NJ (Stock No. 005304) at least once to establish the colony.
Allele Name | targeted mutation 4, Tyler Jacks |
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Allele Type | Targeted (Conditional ready (e.g. floxed), No functional change) |
Allele Synonym(s) | caKRas; KR; K-Ras(G12D)fl; KrasG12D; K-RasL; KrasLox; K-rasLSL; KrasLSL-G12D; Kras2tm4Tyj; Kras2tm14Tyj; K-RasG12D; Lox-Stop-Lox-KrasG12D; LSL-Kras G12D; LSL-K-ras G12D; LSL-KrasG12D; LSL-K-rasG12D; LSL-KrasG12D |
Gene Symbol and Name | Kras, Kirsten rat sarcoma viral oncogene homolog |
Gene Synonym(s) | |
Strain of Origin | 129S4/SvJae |
Chromosome | 6 |
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. |
Mutations Made By | Dr. Tyler Jacks, Massachusetts Institute of Technology |
When maintained as a live colony, heterozygotes may be bred. Homozygotes are embryonic lethal.
When using the B6N.Cg-Krastm4Tyj/CjDswJ mouse strain in a publication, please cite the originating article(s) and include JAX stock #019104 in your Materials and Methods section.
Facility Barrier Level Descriptions
Service/Product | Description | Price |
---|---|---|
Heterozygous or wild type for Kras<tm4Tyj> |
Frozen Mouse Embryo | B6N.Cg-Kras<tm4Tyj>/CjDswJ Frozen Embryo | $2595.00 |
Frozen Mouse Embryo | B6N.Cg-Kras<tm4Tyj>/CjDswJ Frozen Embryo | $2595.00 |
Frozen Mouse Embryo | B6N.Cg-Kras<tm4Tyj>/CjDswJ Frozen Embryo | $3373.50 |
Frozen Mouse Embryo | B6N.Cg-Kras<tm4Tyj>/CjDswJ Frozen Embryo | $3373.50 |
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The Jackson Laboratory has rigorous genetic quality control and mutant gene genotyping programs to ensure the genetic background of JAX® Mice strains as well as the genotypes of strains with identified molecular mutations. JAX® Mice strains are only made available to researchers after meeting our standards. However, the phenotype of each strain may not be fully characterized and/or captured in the strain data sheets. Therefore, we cannot guarantee a strain's phenotype will meet all expectations. To ensure that JAX® Mice will meet the needs of individual research projects or when requesting a strain that is new to your research, we suggest ordering and performing tests on a small number of mice to determine suitability for your particular project. We do not guarantee breeding performance and therefore suggest that investigators order more than one breeding pair to avoid delays in their research.
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