B6.FVB-Tg(Ddx4-cre)1Dcas/KnwJ

Stock number: 018980
Product name: Vasa-Cre
Research areas: Research Tools

Description

Ddx4-Cre (Vasa-Cre) transgenic mice have Cre recombinase expression directed to male and female embryonic germ cells. These mice may be useful in generating conditional germ cell knock-outs in both males and females for studies including infertility, gonadogenesis, gametogenesis, and the assembly, activation, and growth of primordial follicles.

In Goodwin et al. 2019 Genome Res. 29:494, it was discovered that Ddx4-Cre founder line 1 has more than 20 transgene copies integrated on chromosome 18 that caused a 1098 kbp deletion encompassing two loci - neuropilin (NRP) and tolloid (TLL)-like 1 (Neto1) and cerebellin 2 precursor protein (Cbln2).

Detailed description

Vasa-Cre (Ddx4-Cre) transgenic mice express Cre recombinase under the direction of the mouse Ddx4 promoter.

In Goodwin et al. 2019 Genome Res. 29:494, analysis of the Ddx4-Cre parental strain (Stock No. 006954) identified more than 20 transgene copies integrated on chromosome 18 that caused a 1098 kbp deletion encompassing two loci - neuropilin (NRP) and tolloid (TLL)-like 1 (Neto1) and cerebellin 2 precursor protein (Cbln2). The deletion results in a functional knock-out of both genes in homozygous mice.

Mice hemizygous for this Ddx4-Cre transgene are viable and fertile. Transgenic cre activity is directed to male and female germ cells starting at embryonic day (e)15-e18. When bred with mice containing a loxP-flanked sequence of interest, Cre-mediated recombination will result in deletion of the flanked sequence. In such breedings, occasional hemizygous mice may exhibit variegated cre expression in skin epithelium or global cre expression (<20% incidence). Differential parent-of-origin transgene expression is observed. When the mother harbors Ddx4-Cre, virtually all progeny undergo global Cre-mediated recombination, even those that do not inherit the transgene (which may be useful in converting a "floxed" allele to a null while obviating the need to perform additional crosses to remove the transgene). To achieve germ-line specific Cre-mediated recombination in offspring, paternal Ddx4-Cre mice should be used.

In crosses with some floxed alleles, global recombination may occur even when males are used as the Dxd4-Cre carriers. The basis of this "paternal" effect is not known, but may relate to the presence of Cre protein in sperm. This global recombination can occur more frequently with older males. Thus, when paternal-effect global recombination is observed, it is recommended that the youngest available Ddx4-Cre males be used for breeding (ideally 5-6 weeks, but less than 9 weeks of age). Once a male has proven to repeatedly give rise to globally-recombined progeny, he should no longer be used as a breeder.

These Ddx4-Cre mice may be useful in generating conditional germ cell knock-outs in both males and females for studies including infertility, gonadogenesis, gametogenesis, and the assembly, activation, and growth of primordial follicles.

While another germ line cre-expressing strain, ZP3-Cre (see Stock No. 003651), permits recombination/deletion of loxP-flanked genes in growing follicles, Ddx4-Cre mice have additional cre expression in primordial follicles (early oogenesis) and in the male germline.

If the recombinase activity pattern of this allele is further characterized by the Genetic Resource Science group at The Jackson Laboratory, such findings will be reported on the Mouse Genome Informatics (MGI) Allele Detail entry (Tg(Ddx4-cre)1Dcas). This same information would also be found searching the MGI Recombinase Activity database.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.

Development

The Vasa-Cre (Ddx4-Cre) transgenee contains a 5.6 kb fragment of the mouse Vasa (Ddx4) promoter, beta-globin intron, Cre recombinase open reading frame with nuclear localization signal, and SV40 polyadenylation signal. The transgene was microinjected into FVB oocytes (see transgene integration and genomic deletion note below). Transgenic mice (founder line not provided) on the FVB genetic background were bred together for many generations prior to arrival at The Jackson Laboratory in 2007 as Stock No. 006954). Some of these mice were then backcrossed to C57BL/6J for 10 generations to generate this C57BL/6J-congenic Ddx4-Cre mouse line (Stock No. 018960).

In Goodwin et al. 2019 Genome Res. 29:494, analysis of the Ddx4-Cre parental strain (Stock No. 006954) identified more than 20 transgene copies integrated on chromosome 18 that caused a 1098 kbp deletion encompassing two loci - neuropilin (NRP) and tolloid (TLL)-like 1 (Neto1) and cerebellin 2 precursor protein (Cbln2).

Allele

Symbol: Tg(Ddx4-cre)1Dcas
Name: transgene insertion 1, Diego H Castrillon
MGI accession ID: MGI:3757577
Generation method: Transgenic
Attributes: Recombinase-expressing; Null/Knockout
Synonyms: Mvh-Cre; Vasa-Cre
Marker symbol: Tg(Ddx4-cre)1Dcas
Marker name: transgene insertion 1, Diego H Castrillon
Marker synonyms: Vasa-cre
Chromosome: 18
Strain of origin: FVB
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: male and female germ cells starting at embryonic day (e)15-e18
Molecular note: A 5.6kb fragment of the Ddx4 promoter was ligated to the cre open reading frame with an engineered nuclear localization signal. Eight transgenic lines were created but only two possessed expressing in the gonads as early as E15. When the cre transgene is maternally expressed, all progeny can show ubiquitous recombination even if the cre is not inherited, likely due to perdurance of cre protein in the egg. The transgene integrated into chromosome 18 causing a 1098 Kb deletion and deleting the genes Neto1 and Cbln2. The deletion results in a functional knock-out of both genes in homozygous mice. Founder line 1 has a copy number of greater than 20.