STOCK Myf5^{tm1(cre/Esr1*)Trdo}/J

Stock number: 023342
Product name: Myf5^CreER
Research areas: Research Tools

Description

These mice express muscle specific tamoxifen-inducible cre, and may be useful when evaluating embryonic muscle-specific cell lineage contributions to the adult satellite cell compartment.

Detailed description

Myf5^CreER knock-in mice express the CreERTM fusion protein from the endogenous myogenic factor 5 (Myf5) promoter/enhancer elements. MYF5 is expressed during muscle development and is involved in regulating myogenesis. MYF5 is also expressed in a fraction of satellite cells. Homozygotes are viable and fertile. Cre-ERTM fusion gene activity is inducible and can be observed following tamoxifen administration. As such, when these mice are bred with mice containing loxP-flanked sequences, tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequences in muscle cells of the offspring.

For example, when bred to B6.129X1-Gt(ROSA)26Sortm1(EYFP)Cos/J mice (Stock No. 006148), tamoxifen inducible excision of the loxP-flanked STOP sequence results in YFP fluorescence in Myf5-expressing muscle cells of the offspring at different developmental stages.

The Cre-ERTM fusion protein consists of Cre recombinase fused to a G525R mutant form of the mouse estrogen receptor ligand binding domain which fails to bind the naturally occurring ligand 17b-estradiol at normal concentrations but retains relatively high affinity for the synthetic ligand 4-hydroxytamoxifen (4-OHT). Restricted to the cytoplasm, Cre-ERTM 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 was designed to place an internal ribosome entry site (IRES) fused to a CreERTM fusion gene (CreER^TM; Cre recombinase fused to a G525R mutant form of the mouse estrogen receptor ligand binding domain) downstream of the stop codon in exon 3 of the myogenic factor 5 (Myf5) gene. A neomycin resistance gene (neo), flanked by frt sites, was inserted downstream of the IRES-CreERTM cassette. This construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl⁺-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts and chimeric males were bred with C57BL/6 females. These mice were bred to C57BL/6J mice for at least 2 generations and then with FVB mice for at least 2 generations. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Myf5^{tm1(cre/Esr1*)Trdo}
Name: targeted mutation 1, Thomas A Rando
MGI accession ID: MGI:5509335
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible
Marker symbol: Myf5
Marker name: myogenic factor 5
Chromosome: 10
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: When these mice are bred with mice containing loxP-flanked sequences, tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequences in muscle cells of the offspring.
Molecular note: A targeting vector was designed to place an internal ribosome entry site (IRES) fused to a CreERTM fusion gene (CreERTM; Cre recombinase fused to a G525R mutant form of the mouse estrogen receptor ligand binding domain) downstream of the stop codon in exon 3 of the Myf5 gene. A neomycin resistance marker, flanked by frt sites, was inserted downstream of the IRES-CreERTM cassette. This construct was electroporated into R1 embryonic stem cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts and chimeric males were bred with C57BL/6 females.