STOCK Tg(Wnt1-cre/ERT)1Alj/J

Stock number: 008851
Product name: Wnt1-CreER^T
Research areas: Neurobiology Research, Research Tools

Description

These transgenic mice express a tamoxifen-inducible cre recombinase directed by the wingless-related MMTV integration site 1 (Wnt1) promoter/regulatory sequences. When induced, cre activity is observed in the Wnt1-expressing cells; including midbrain, developing neural tube, migrating neural crest cells and dopaminergic neuron populations.

Detailed description

Mice hemizygous for the Wnt1-CreER^T transgene are viable and fertile, with expression of a tamoxifen-inducible Cre recombinase (Cre-ER^T) directed by mouse Wnt1 promoter/enhancer elements. CreER^T fusion gene activity is inducible; observed following tamoxifen administration. As such, when Wnt1-CreER^T transgenic mice are bred with mice containing loxP-flanked sequences, tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequences in the Wnt1-expressing cells of the offspring. Depending upon when tamoxifen is administered, Cre recombinase activity may be observed throughout the mesencephalon (midbrain) and rhombomere 1 (~E8.5), or more restricted to the dorsal and ventral midline of the midbrain and a ring around the posterior border of the midbrain (E9.5-12.5), lateral edge of the neural plate (lower rhombic lip) in rhombomere2- rhombomere7, spinal cord and diencephalon, as well as progenitor populations giving rise to migrating neural crest cells and dopaminergic neuron populations (E9.5-12.5). The donating investigator has not determined the phenotype of homozygous mice to date (January 2012).

The Cre-ER^T fusion protein consists of Cre recombinase fused to a G521R mutant form of the human estrogen receptor binding domain 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-ER^T 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 Wnt1-CreER^T transgene was designed with mouse Wnt1 promoter/enhancer elements (from the pWexp3 plasmid) upstream of the Cre-ER^T fusion gene (Cre recombinase fused to a G521R mutant form of the human estrogen receptor ligand binding domain). Specifically, the transgene was created by inserting the CreERT fusion gene (followed by an 825 bp untranslated LacZtag sequence to provide a tag for the transgene derived RNA) into a 10 kbp modified mouse Wnt1 genomic sequence at a polylinker site between the promoter and enhancer (the Wnt1 genomic sequence spans from approximately 1 kbp upstream of the translation initiation codon to approximately 5.5 kbp downstream of the polyA signal, and is modified with a polylinker that disrupts the translational start site). This transgene was injected into Swiss Webster zygotes. Founder mice were identified and bred to Swiss Webster mice to generate the colony. Hemizygous mice were routinely bred to Swiss Webster mice for many generations (and may also have been bred to Gt(ROSA)26Sor^tm1Sor mutant mice [on an undisclosed genetic background]) prior to sending to The Jackson Laboratory Repository. In addition, the donating investigator reports that although these mice harbor no additional mutant loci, they may contain incidental genetic background contributions as a result of past matings with other mutant mouse strains. Upon arrival, Wnt1-CreER^T transgenic mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony at The Jackson Laboratory Repository.

Allele

Symbol: Tg(Wnt1-cre/ERT)1Alj
Name: transgene insertion 1, Alexandra L Joyner
MGI accession ID: MGI:4359399
Generation method: Transgenic
Attributes: Recombinase-expressing; Inducible
Marker symbol: Tg(Wnt1-cre/ERT)1Alj
Marker name: transgene insertion 1, Alexandra L Joyner
Chromosome: UN
Strain of origin: Swiss Webster
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: Cre recombinase activity is observed throughout the mesencephalon (midbrain) and rhombomere 1 (~E8.5), or more restricted to the dorsal and ventral midline of the midbrain and a ring around the posterior border of the midbrain (E9.5-12.5), lateral edge of the neural plate (lower rhombic lip) in rhombomere2- rhombomere7, spinal cord and diencephalon, as well as progenitor populations giving rise to migrating neural crest cells and dopaminergic neuron populations (E9.5-12.5).
Molecular note: cDNA encoding the cre/ERT fusion protein was inserted into a vector containing the Wnt1 enhancer. Two lines showing similar expression patterns in reporter mice were generated.