STOCK Msi1^tm2.1Geno/ReyaJ

Stock number: 035370
Product name: Msi1^flox
Research areas: Cancer Research, Cell Biology Research, Research Tools

Description

Msi1^flox/flox mice possess loxP sites flanking exons 1-4 of the musashi RNA-binding protein 1 (Msi1) gene. These mice can be used to study the impact of Msi1 loss in different tissues in vivo, and may help with cancer diagnostic and therapeutic studies.

Detailed description

Msi1^flox/flox mice possess loxP sites flanking exons 1-4 of the musashi RNA-binding protein 1 (Msi1) gene. Msi1 encodes an RNA binding protein that plays a role in post-transcriptional gene regulation. It is involved in maintenance of stem cells in the mammalian nervous system. Msi1 is also highly upregulated in many aggressive cancers, including pancreatic cancer and colon cancer, and is a poor prognostic factor for outcome. Mice that are homozygous for this allele are viable and fertile. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have exons 1-4 deleted in cre-expressing tissues. Msi1^flox/flox mice can also be bred to mice that express a tamoxifen-regulatable Cre-ER allele to conditionally delete Msi1 in CreER-expressing tissues following tamoxifen delivery.

Development

The Msi1^flox targeting vector was designed to insert a loxP site upstream of exon 1 of the musashi RNA-binding protein 1 (Msi1) gene, and a frt-flanked neomycin resistance (neo) cassette followed by a second loxP site downstream of exon 4. The construct was electroporated into 129Sv-derived embryonic stem (ES) cells and correctly targeted ES cells were injected into blastocysts. The resulting chimeric mice were bred with flp recombinase expressing mice to remove the neo cassette, and resulting mice were subsequently bred together to remove the flp-expressing transgene. Offspring were further bred to C57BL/6J mice for at least 10 generations by the donating lab (see SNP note below). Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

In 2020, a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. Markers on Chromosomes 2, 3, 7, 8, 10, 11, and 12 were segregating with 129, suggesting an incomplete backcross. Also, one of the 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed genetic background.

Allele

Symbol: Msi1^tm2.1Geno
Name: targeted mutation 2.1, Genoway
MGI accession ID: MGI:6324498
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed)
Synonyms: Msi1^f; Msi1^flox
Marker symbol: Msi1
Marker name: musashi RNA-binding protein 1
Marker synonyms: m-Msi-1; Msi1h; Musahi1
Chromosome: 5
Strain of origin: 129
Molecular note: The targeting vector is designed to insert a loxP site upstream of exon 1 and an FRT-flanked neomycin resistance (neo) cassette followed by a second loxP site downstream of exon 4. Cre-mediated recombination removed the floxed neo cassette.