En1-CreERT1 mutant mice harbor the Cre-ERT1 fusion gene under control of the endogenous engrailed 1 locus. When En1-CreERT1 mice are bred with mice containing a loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the flanked sequences in En1-expressing tissues (including the mesencephalon and rhombomere 1, as well as the developing cerebellum, dermis, and limbs).
Dr. Alexandra L Joyner, Memorial Sloan-Kettering Cancer Center
Genetic Background | Generation |
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|
Allele Type | Gene Symbol | Gene Name |
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Targeted (Recombinase-expressing, Inducible) | En1 | engrailed 1 |
While mice heterozygous for this En1-CreERT1 mutation are viable and fertile, homozygotes die at birth. Because the Cre-ERT1 fusion gene is inserted between the transcriptional start site and the first exon of the engrailed 1 (En1) gene, tamoxifen-inducible cre activity is controlled by the endogenous En1 regulatory elements. The Cre-ERT1 fusion protein consists of Cre recombinase fused to a triple mutant form of the human estrogen receptor; which does not bind its natural ligand (17β-estradiol) at physiological concentrations but will bind the synthetic estrogen receptor ligands 4-hydroxytamoxifen (OHT) and, with lesser sensitivity, ICI 182780. Restricted to the cytoplasm, Cre-ERT1 can only gain access to the nuclear compartment after exposure to OHT. To counteract the mixed estrogen agonist effects of tamoxifen injections, which can result in late fetal abortions in pregnant mice, progesterone may be coadministered. When these En1-CreERT1 mice are bred with mice containing a loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the flanked sequences in En1-expressing tissues (including the mesencephalon and rhombomere 1, as well as the developing cerebellum, dermis, and limbs).
Of note, these mice may also be useful in conjunction with other engrailed mutants (such as Stock No. 007912, Stock No. 007916, Stock No. 007918, Stock No. 007924, and Stock No. 007925).
A targeting construct was designed with a CreERT1 fusion gene (Cre-ERT1; Cre recombinase fused to a G400V/L539A/L540A triple mutation of the human estrogen receptor ligand binding domain) followed by a reverse-oriented loxP-flanked neo cassette. This construct was inserted between the transcriptional start site and first exon of the targeted gene (replacing the translational start site) via electroporation into 129S6/SvEvTac-derived W4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric males were bred to Black Swiss females. The resulting En1-CreERT1-neo heterozygotes were then bred to cre expressing mice (on a Swiss Webster genetic background) to remove the neo cassette, generating En1-CreERT1 offspring (with a single loxP site remaining after the Cre-ERT1 fusion gene). These En1-CreERT1 mutant mice were bred to Swiss Webster mice for many generations prior to arrival at The Jackson Laboratory. In addition, the donating investigator reports that although these mice harbor no additional mutant loci, they may contain incidental genetic background contributions as a result of past matings with other mutant mouse strains. Upon arrival, En1-CreERT1 mice were bred to 129S1/SvImJ (Stock No. 002448) for at least one generation to establish the colony.
Expressed Gene | cre/Esr1, Cre recombinase and estrogen receptor 1 fusion gene, |
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Site of Expression | mesencephalon and rhombomere 1, as well as the developing cerebellum, dermis, and limbs (after induction) |
Allele Name | targeted mutation 7, Alexandra L Joyner |
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Allele Type | Targeted (Recombinase-expressing, Inducible) |
Allele Synonym(s) | En1tm7(cre)Alj; En1-CreERT1; En1-CreERT1; Engrailed1-Cre |
Gene Symbol and Name | En1, engrailed 1 |
Gene Synonym(s) | |
Expressed Gene | cre/Esr1, Cre recombinase and estrogen receptor 1 fusion gene, |
Site of Expression | mesencephalon and rhombomere 1, as well as the developing cerebellum, dermis, and limbs (after induction) |
Strain of Origin | 129S6/SvEvTac |
Chromosome | 1 |
Molecular Note | A tamoxifen dependent form of cre recombinase (CreER) and a loxP-flanked neo in reverse orientation were inserted into the locus. The neo was removed in vivo via Cre-mediated recombination. |
Mutations Made By | Dr. Alexandra Joyner, Memorial Sloan-Kettering Cancer Center |
When maintaining a live colony, heterozygous mice may be bred to wildtype siblings. The donating investigator reports that homozygotes die at birth. Of note, to ensure the mutant phenotype of these En1-mutant mice, avoid crossing these mice onto the C57BL/6 genetic background (as the phenotype of En1-null mice is rescued on the C57BL/6 genetic background).
When using the STOCK En1tm7(cre/ESR1)Alj/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #007917 in your Materials and Methods section.
Facility Barrier Level Descriptions
Service/Product | Description | Price |
---|---|---|
Heterozygous or wild-type for En1<tm7(cre/ESR1)Alj> |
Frozen Mouse Embryo | STOCK En1<tm7(cre/ESR1)Alj>/J | $2595.00 |
Frozen Mouse Embryo | STOCK En1<tm7(cre/ESR1)Alj>/J | $2595.00 |
Frozen Mouse Embryo | STOCK En1<tm7(cre/ESR1)Alj>/J | $3373.50 |
Frozen Mouse Embryo | STOCK En1<tm7(cre/ESR1)Alj>/J | $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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