B6(SJL)-Pou5f1^{tm1.1(cre/Esr1*)Yseg}/J

Stock number: 016829
Product name: Oct4-MerCreMer
Research areas: Research Tools

Description

These knock-in mice (also referred to as Oct4-MerCreMer mice) express a tamoxifen-inducible cre recombinase from the endogenous promoter/enhancer elements of the Pou5f1 gene. When induced, cre activity is observed in Pou5f1 expressing cells in embryos and in Induced pluripotent stem (iPS) cells derived from these mice. These mice may be useful for generating conditional mutations for studying lineage tracing, and production of cell lines and targeted knock-out mutations.

Detailed description

These targeted mutation mice have a tamoxifen inducible Cre-mediated recombination system ("MerCreMer") driven by the endogenous Pou5f1 (POU domain, class 5, transcription factor 1) promoter. Mice that are heterozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. The viability and fertility of homozygotes is not yet known. Inducible Cre mediated recombination occurs in Pou5f1 (Oct4) expressing cells in embryos and in iPS cells derived from these mice. Of note, this double fusion protein has substantially greater Cre recombinase activity with less promiscuity compared with a single CreMer fusion protein. As the cre is flanked on each end with a mutated murine estrogen receptor ligand binding domain (amino acids 281-599, G525R); Cre expression is tamoxifen inducible yet estrogen insensitive. These Oct4-Inducible Cre mice may be useful for generating conditional mutations for studying lineage tracing, and production of cell lines and targeted mutations (knockouts).

The cre/Esr1* fusion protein consists of Cre recombinase fused to a G525R mutant form of the mouse 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/Esr1* 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.

Development

A targeting vector containing an FRT-site flanked NEO cassette and IRES-MerCreMer sequence was inserted in the 3' UTR of Oct4/Pou5f1 locus. The construct was electroporated into C57BL/6 derived embryonic stem (ES) cells from inGenious Targeting Laboratory. Correctly targeted ES cells were injected into recipient B6(Cg)-Tyr^c-2J/J or BALB/c blastocysts. The resulting chimeric animals were crossed to B6.Cg-Tg(ACTFLPe)9205Dym/J (Stock No. 005703) mice to remove the FRT site flanked selection cassette. The mice were then backcrossed to C57BL/6NHsd for 8 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

Symbol: Pou5f1^{tm1.1(cre/Esr1*)Yseg}
Name: targeted mutation 1.1, Yoav Segal
MGI accession ID: MGI:5049897
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible
Marker symbol: Pou5f1
Marker name: POU domain, class 5, transcription factor 1
Chromosome: 17
Strain of origin: C57BL/6
Expressed genes: cre/Esr1,Cre recombinase and estrogen receptor 1 fusion gene,
Site of expression: Inducible Cre mediated recombination occurs in Pou5f1 expressing cells in embryos and in induced pluripotent stem cells derived from these mice.
Molecular note: A targeting vector containing an FRT-site flanked NEO cassette and IRES-MerCreMer sequence was inserted in the 3' UTR of Oct4/Pou5f1 locus. The construct was electroporated into C57BL/6 derived embryonic stem (ES) cells from inGenious Targeting Laboratory. Correctly targeted ES cells were injected into recipient B6(Cg)-Tyrc-2J/J or BALB/c blastocysts. The resulting chimeric animals were crossed to B6.Cg-Tg(ACTFLPe)9205Dym/J mice to remove the FRT site flanked selection cassette.