B6(129S4)-Scx^{tm2.1(cre/ERT2)Stzr}/J

Stock number: 032132
Product name: Scx^CreERT2
Research areas: Research Tools

Description

These Scx-IRES-CreERT2 knock-in mice express a tamoxifen-inducible Cre recombinase under the direction of the mouse Scx, scleraxis, gene promoter. When induced, Cre recombinase activity is detected in tendons and ligaments, with the strongest recombination in mice neonatal to 2 months of age. They are suitable for use in applications related to the study of tendons, ligaments and connective tissue.

Detailed description

These Scx-IRES-CreERT2 knock-in mice a tamoxifen-inducible Cre recombinase from the endogenous promoter/enhancer elements of the Scx, scleraxis, gene. Cre recombinase activity is detected in limb buds at E11.5, and in tendons and ligaments at E18.5. At 5 days of age, Cre recombinase activity is detected in tendons, epitendon, tendon sheath, ligaments, skeletal insertion and annulus fibrosus of the tail. Other tissues exhibiting Cre recombinase activity include lung, heart, kidney and testis.

Mice that are homozygous for the transgene are viable and fertile.

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.

 

Development

The Scx^cre/ERT2 targeting was used to insert an IRES-CreERT2 cassette into the 3’UTR of exon 2 of the scleraxis scleraxis bHLH transcription factor (Scx) gene. The construct also contained a frt-flanked neomycin resistance cassette. The construct was electroporated into unspecified C57BL/6 derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were then bred to ROSA26::FLPe mice (Stock No. 009086) mice to remove the neo cassette. Resulting mice were backcrossed to C57BL/6J mice (Stock No. 000664) for many generations by the donating laboratory. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes.

Allele

Symbol: Scx^{tm2.1(cre/ERT2)Stzr}
Name: targeted mutation 2.1, Ronen Schweitzer
MGI accession ID: MGI:6508700
Generation method: Targeted
Attributes: Recombinase-expressing
Synonyms: Scx^cre/ERT2; Scx^CreERT2
Marker symbol: Scx
Marker name: scleraxis
Marker synonyms: bHLHa41; bHLHa48; Scl; SCXA; SCXB
Chromosome: 15
Strain of origin: C57BL/6
Molecular note: An IRES-CreERT2 sequence was inserted between the stop codon and 3′ UTR in exon 2. The construct also contained a FRT-flanked neomycin resistance cassette. Flp-mediated recombination removed the neo cassette.