A CreERT2 fusion protein sequence inserted downstream of the Pax7 stop codon allows endogenous PAX7 expression in these mice while permitting specific conditional labeling, manipulation, and deletion of satellite cells.
Gabrielle Kardon, University of Utah
Genetic Background | Generation |
---|---|
N8pN1+N1F4
|
Allele Type | Gene Symbol | Gene Name |
---|---|---|
Targeted (Recombinase-expressing, Inducible) | Pax7 | paired box 7 |
An internal ribosome entry site (IRES)-CreERT2 fusion protein was inserted 8 bp downstream of the stop codon of the paired box gene 7 (Pax7) gene. PAX7 is a marker for satellite cells, adult muscle stem cells required for muscle regeneration after injury. Unlike B6;129-Pax7tm2.1(cre/ERT2)Fan/J mice (Stock No. 012476), in which PAX7 expression is abolished, PAX7 is expressed and functional in these mice. Homozygotes are viable and fertile. Cre-ERT2 fusion gene activity is inducible and only observed following tamoxifen administration. When these mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in the Pax7-expressing cells of the offspring. For example when bred to B6;129-Gt(ROSA)26Sortm1(DTA)Mrc/J mice (Stock No. 010527), tamoxifen induction results in diphtheria toxin A expression in satellite cells, and subsequent ablation of satellite cells. These double mutant mice exhibit complete loss of muscle regeneration, misregulation of fibroblasts, and an increase of muscle connective tissue.
The Cre-ERT2 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 or tamoxifen) and, with lesser sensitivity, ICI 182780. Restricted to the cytoplasm, Cre-ERT2 can only gain access to the nuclear compartment after exposure to tamoxifen. To counteract the mixed estrogen agonist effects of tamoxifen injections, which can result in late fetal abortions in pregnant mice, progesterone may be coadministered.
A targeting vector was designed to insert an internal ribosome entry site (IRES)-CreERT2 fusion protein, followed by a frt-flanked neomycin (neo) selection cassette, 8bp downstream of the endogenous stop codon of the paired box gene 7 (Pax7) gene. This construct was electroporated into (129S6/SvEvTac x C57BL/6NCr)F1-derived G4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric males were bred with C57BL/6 females. The resulting mice were bred to 129S4/SvJaeSor-Gt(ROSA)26Sortm1(FLP1)Dym/J mice (Stock No. 003946) to remove the neo cassette. These Pax7cre/ERT2mice were backcrossed to C57BL/6J for at least 8 generations. Upon arrival, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation.
Expressed Gene | cre/ERT2, Cre recombinase and estrogen receptor 1 (human) fusion gene, |
---|---|
Site of Expression | When these mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in Pax7-expressing satellite cells, and subsequent ablation of satellite cells in the offspring. |
Allele Name | targeted mutation 1, Gabrielle Kardon |
---|---|
Allele Type | Targeted (Recombinase-expressing, Inducible) |
Allele Synonym(s) | |
Gene Symbol and Name | Pax7, paired box 7 |
Gene Synonym(s) | |
Expressed Gene | cre/ERT2, Cre recombinase and estrogen receptor 1 (human) fusion gene, |
Site of Expression | When these mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in Pax7-expressing satellite cells, and subsequent ablation of satellite cells in the offspring. |
Strain of Origin | (129S6/SvEvTac x C57BL/6NCrl)F1 |
Chromosome | 4 |
Molecular Note | An IRES-cre/ERT2 and an FRT flanked neomycin selection cassette were inserted 8 bp after the endogenous stop codon. The selection cassette was subsequently removed by crossing to a Gt(ROSA)26Sortm1(FLP1)Dym mouse line. Endogenous gene function is preserved. |
Mutations Made By | Gabrielle Kardon, University of Utah |
When maintaining a live colony, homozygous mice may be bred together.
When using the Pax7creER mouse strain in a publication, please cite the originating article(s) and include JAX stock #017763 in your Materials and Methods section.
Service/Product | Description | Price |
---|---|---|
Heterozygous for Pax7<tm1(cre/ERT2)Gaka> |
Frozen Mouse Embryo | B6.Cg-Pax7<tm1(cre/ERT2)Gaka>/J | $2595.00 |
Frozen Mouse Embryo | B6.Cg-Pax7<tm1(cre/ERT2)Gaka>/J | $2595.00 |
Frozen Mouse Embryo | B6.Cg-Pax7<tm1(cre/ERT2)Gaka>/J | $3373.50 |
Frozen Mouse Embryo | B6.Cg-Pax7<tm1(cre/ERT2)Gaka>/J | $3373.50 |
Terms are granted by individual review and stated on the customer invoice(s) and account statement. These transactions are payable in U.S. currency within the granted terms. Payment for services, products, shipping containers, and shipping costs that are rendered are expected within the payment terms indicated on the invoice or stated by contract. Invoices and account balances in arrears of stated terms may result in The Jackson Laboratory pursuing collection activities including but not limited to outside agencies and court filings.
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.
What information were you hoping to find through your search?
How easy was it to find what you were looking for?
We may wish to follow up with you. Enter your email if you are happy for us to connect and reachout to you with more questions.
Please Enter a Valid Email Address
Thank you for sharing your feedback! We are working on improving the JAX Mice search. Come back soon for exciting changes.