Exons 1 and 2 of the mouse Bmi1 gene are flanked by loxP sites in this conditional knockout allele. This strain has been useful in studies of stem cell and neurosphere-initiating cells in the adult mouse forebrain.
Sean J Morrison, University of Texas Southwestern Medical Center
Exons 1 and 2 of the mouse Bmi1 (Bmi1 polycomb ring finger oncogene) gene are flanked by loxP sites in this Bmifl conditional knockout allele. Cre-mediated excision of the floxed region results in a knockout allele.
Crosses with nestin-cre animals (see Stock No. 003771) excise the floxed sequence broadly throughout the neuroepithelium by E10.5. The compound mutant mice exhibit loss of BMI1 protein in the cortex and subventricular zone (SVZ), as determined by western blot, and Bmi1 transcripts in SVZ cells, GlastmidEGFRhighPlexinB2highCD24-/lowO4/PSA-NCAM-/lowTer119/
CD45- (GEPCOT) cells, and pre-GEPCOT cells, as determined by qRT-PCR. Nestin-Cre; Bmi1fl/fl mice can live for up to 2 years, but exhibit neurological deficits (e.g. ataxia) that worsen as they age. Their brain morphology appears relatively normal, but brain size is reduced. Data indicates that Bmi1 is required for the maintenance of pre-GEPCOT quiescent neural stem cells and GEPCOT neurosphere-initiating cells in vivo.
A loxP-FRT-Neomycin-FRT cassette was placed 5' of exon 1 and a loxP site was introduced to intron 2 via homologous recombination in 129S6/SvEvTac-derived W4 embryonic stem (ES) cells. Resultant chimeric males were bred with B6(Cg)-Tyrc-2J/J females (see Stock No. 000058) to obtain germline transmission. The FRT-flanked neomycin cassette was removed through crosses with Tg(ACTFLPe)9205Dym mice (see Stock No. 005703), leaving exons 1 and 2 flanked by loxP sites. This line was backcrossed to C57BL/Ka for more than 10 generations by the donating laboratory. The albino allele is no longer seen in their colony.
This C57BL/Ka background strain has been cryopreserved as sperm at The Jackson Laboratory, and recovered using C57BL/6J females.
|Allele Name||targeted mutation 1.1, Sean J Morrison|
|Allele Type||Targeted (Conditional ready (e.g. floxed))|
|Gene Symbol and Name||Bmi1, Bmi1 polycomb ring finger oncogene|
|Site of Expression||When bred to mice carrying cre recombinase, compound mutant mice exhibit loss of BMI1 protein in the cortex and subventricular zone of the brain.|
|Strain of Origin||129S6/SvEvTac|
|Molecular Note||A loxP site and an FRT flanked neo cassette were inserted upstream the first coding exon and a loxP site was inserted downstream of exon 2 via homologous recombination. Flp mediated recombination removed the neo cassette.|
Heterozygous and homozygous floxed mice are viable and fertile.
When using the Bmi1fl mouse strain in a publication, please cite the originating article(s) and include JAX stock #028974 in your Materials and Methods section.