STOCK Wt1^{tm1(EGFP/cre)Wtp}/J

Stock number: 010911
Product name: Wt1^GFPCre
Research areas: Cardiovascular Research, Developmental Biology Research, Internal/Organ Research, Reproductive Biology Research, Research Tools

Description

The Wt1^GFPCre knock-in allele in these mice both abolishes Wilms tumor 1 homolog gene function and expresses an EGFPCre fusion protein directed to proepicardium and epicardium by the Wt1 promoter/enhancer elements. As Wt1 is expressed in the developing genitourinary system and in the mesothelia overlying most visceral organs, these mutant mice may be useful as fluorescent/Cre-lox tools for lineage-tracing/marking Wt1-expressing cells for studying cardiomyocytes in the developing heart.

Detailed description

Homozygous mice die between embryonic day (E)13.5 and birth with defects of heart, kidney, gonads, and multiple other organs. Heterozygous (Wt1^GFPCre/+) mice are viable and fertile. The Wt1^GFPCre "knock-in" allele both abolishes Wt1 gene function and expresses an enhanced green fluorescent protein-Cre recombinase fusion protein (EGFPCre) from the Wt1 promoter/enhancer elements. In heart from heterozygous mice, EGFPCre expression is directed to proepicardium and epicardium from E9.5 to E15.5, and is not found in the myocardium. When bred to mice containing loxP-flanked sequences, the resulting offspring will have Cre-mediated deletion of the floxed sequences in the Wt1-expressing cells (and their descendants). As Wt1 is expressed in the developing genitourinary system and in the mesothelia overlying most visceral organs, these mutant mice may be useful as fluorescent/Cre-lox tools for lineage-tracing/marking Wt1-expressing cells for studying cardiomyocytes in the developing heart.

If using these Wt1^GFPCre mice with a Rosa-lacZ reporter allele, the donating investigator reports a preference for using the Gt(ROSA)26Sor^tm1Sho allele (reporting that other floxed alleles can be more broadly recombined by this Wt1^GFPCre allele; perhaps due to transient, low level expression in the early embryo).

Of note, the Wt1^GFPCre strain breeds poorly with non-productive matings and small litter sizes when it is too inbred. Therefore, every third generation, The Jackson Laboratory breeds heterozygous mice to B6129SF1/J hybrid mice (Stock No. 101043) to maintain hybrid vigor. Wt1^GFPCre mice exhibit whisker picking.

Development

A targeting vector was designed to replace the coding portion of exon 1 of the Wt1 (Wilms tumor 1 homolog) locus with a DNA encoding an enhanced green fluorescent protein-Cre recombinase fusion protein (EGFPCre; bp 323-2481 from pBS592) followed by an frt-flanked pgkNeo cassette. The donating investigator reports that this construct was electroporated into 129S4/SvJae-derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric mice were bred with outbred Swiss Webster (CFW) mice to originate the colony. To remove the pgkNeo cassette, mutant mice were bred with Actin-FLPe mice (mostly C57BL/6 genetic background; see Stock No. 005703). The resulting Wt1^GFPCre mice were subsequently mated with outbred Swiss Webster (CFW) mice for several generations (and the FLPe transgene was removed) prior to sending to The Jackson Laboratory Repository in 2009. Upon arrival, sperm was cryopreserved. To generate our live colony, an aliquot of the frozen sperm was used to fertilize oocytes from B6129SF1/J hybrid females (Stock No. 101043). Our live colony was maintained thereafter by breeding heterozygous mice with wildtype mice from the colony and to B6129SF1/J mice.

Allele

Symbol: Wt1^{tm1(EGFP/cre)Wtp}
Name: targeted mutation 1, William T Pu
MGI accession ID: MGI:3801681
Generation method: Targeted
Attributes: Recombinase-expressing
Marker symbol: Wt1
Marker name: Wilms tumor 1 homolog
Chromosome: 2
Strain of origin: 129S4/SvJae
Expressed genes: cre,cre recombinase,bacteriophage P1; GFP,Green Fluorescent Protein,
Site of expression: EGFPCre fusion protein expression is directed to proepicardium and epicardium.
Molecular note: Exon 1 was replaced with an EGFP-cre derived from pBS592 and an frt-flanked neo cassette. Germ line, flp-mediated recombination was used to remove the neo cassette.