These mice harbor a Osr1eGFPCreERt2 (Osr1GCE) "knock-in" allele that both abolishes Osr1 (odd-skipped related 1 (Drosophila)) gene function and expresses EGFP and creERT2 from the Osr1 promoter/enhancer elements. While EGFP expression is observed in intermediate mesoderm and dorsal lateral plate mesoderm of developing embryos (~E8.5), Cre-ERT2 fusion gene activity is inducible; observed in the same cells only following tamoxifen administration. These Osr1GCE mice may be useful for lineage-tracing/marking Osr1-expressing cells for studying metanephric kidney development, as well as vascular, heart, and urogenital development.
Andrew P McMahon, University of Southern California
Genetic Background | Generation |
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|
Allele Type | Gene Symbol | Gene Name |
---|---|---|
Targeted (Recombinase-expressing, Inducible) | Osr1 | odd-skipped related transcription factor 1 |
Homozygous mice die upon birth with multiple abnormalities of the heart and urogenital system (among other tissues). Heterozygous mice are viable and fertile. The Osr1eGFPCreERt2 (Osr1GCE) "knock-in" allele both abolishes Osr1 gene function and expresses an eGFPCreERt2 fusion protein (EGFP and creERT2 fusion protein from the Osr1 promoter/enhancer elements). While EGFP immunofluorescence is observed in intermediate mesoderm and dorsal lateral plate mesoderm of developing embryos (~E8.5), Cre-ERT2 fusion gene activity is inducible; observed in the same cells only following tamoxifen administration. As such, when Osr1GCE mice are bred with mice containing loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in the Osr1-expressing cells of the offspring. Of note, removal of the frt-flanked neo cassette is reported to result in ectopic Cre recombinase expression in the absence of tamoxifen.
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 with a cDNA encoding an eGFPCreERt2 (GCE) fusion protein. Specifically, this targeting vector contained an enhanced green fluorescent protein (EGFP) and a CreERT2 fusion gene (Cre-ERT2; Cre recombinase fused to a G400V/M543A/L544A triple mutation of the human estrogen receptor ligand binding domain), a polyA signal, and a frt-flanked PGK-neo-pA cassette. This construct was designed to replace the first ATG codon of the targeted gene with the first ATG codon of the GCE cassette. This construct was electroporated into F1 hybrid (129/Sv x C57BL/6J) embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric mice were bred with C57BL/6J mice. The donating investigator reports that mutant mice were backcrossed to C57BL/6J mice for several generations before arriving at The Jackson Laboratory (see SNP analysis note below). Upon arrival the mice were bred with C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.
A 27 SNP (single nucleotide polymorphism) panel analysis performed by The Jackson Laboratory revealed 10 of 27 markers (8 different chromosomes) that were not C57BL/6 allele-type. These data indicate the mice were not backcrossed to C57BL/6 prior to arrival at The Jackson Laboratory. No single source of genetic background contamination could be determined by this data. The donating investigator suggests there may be some Swiss Webster genetic contributions from a possible mating with R26Hoxd11 mutant mice many years ago.
Expressed Gene | GFP, Green Fluorescent Protein, |
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Expressed Gene | cre/ERT2, Cre recombinase and estrogen receptor 1 (human) fusion gene, |
Site of Expression | GFP immunofluorescence is observed in intermediate mesoderm and dorsal lateral plate mesoderm of developing embryos (~E8.5). |
Allele Name | targeted mutation 1, Andrew P McMahon |
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Allele Type | Targeted (Recombinase-expressing, Inducible) |
Allele Synonym(s) | Osr1eGFPCreERt2; Osr1GCE |
Gene Symbol and Name | Osr1, odd-skipped related transcription factor 1 |
Gene Synonym(s) | |
Expressed Gene | GFP, Green Fluorescent Protein, |
Expressed Gene | cre/ERT2, Cre recombinase and estrogen receptor 1 (human) fusion gene, |
Site of Expression | GFP immunofluorescence is observed in intermediate mesoderm and dorsal lateral plate mesoderm of developing embryos (~E8.5). |
Strain of Origin | Not Specified |
Chromosome | 12 |
Molecular Note | The start codon was replaced with an eGFP/cre/ERT2 cassette followed by an frt flanked neo cassette via homologous recombination. GFP expression was detected in the intermediate mesoderm and dorsal lateral plate mesoderm at E8.5 and E9.5. |
Mutations Made By | Andrew McMahon, University of Southern California |
When maintaining a live colony, heterozygous mice may be bred together, to wildtype siblings, or to C57BL/6J inbred mice (Stock No. 000664). Homozygous mice are not viable.
When using the STOCK Osr1tm1(EGFP/cre/ERT2)Amc/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #009061 in your Materials and Methods section.
Facility Barrier Level Descriptions
Service/Product | Description | Price |
---|---|---|
Heterozygous or wildytpe for Osr1<tm1(EGFP/cre/ERT2)Amc> |
Frozen Mouse Embryo | STOCK Osr1<tm1(EGFP/cre/ERT2)Amc>/J | $2595.00 |
Frozen Mouse Embryo | STOCK Osr1<tm1(EGFP/cre/ERT2)Amc>/J | $2595.00 |
Frozen Mouse Embryo | STOCK Osr1<tm1(EGFP/cre/ERT2)Amc>/J | $3373.50 |
Frozen Mouse Embryo | STOCK Osr1<tm1(EGFP/cre/ERT2)Amc>/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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