B6.Cg-Smad7^tm1.1Ink/J

Stock number: 017008
Product name: Smad7^fl
Strain synonyms: Smad7 flox
Research areas: Cell Biology Research, Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

These Smad7^fl/fl conditional mutant mice may be useful for studying the cellular and mechanical role of TGF-β in immunosuppression in inflammatory and degenerative diseases such as multiple sclerosis.

Detailed description

SMAD7 is an inhibitor of transforming growth factor-β which regulates naive T cell differentiation and inflammatory cellular responses. Smad7^fl/fl mutant mice possess loxP sites flanking exon 1 of the MAD homolog 7 (Smad7) gene. Homozygotes are viable and fertile. When these mutant mice are bred to mice that express Cre recombinase, the resulting offspring will have exon 1 deleted in cre-expressing tissues.

For example, when crossed to a strain expressing CD4-Cre recombinase (Stock No. 017336), this mutant mouse strain exhibits a lower frequency of activated CD4⁺ and CD4⁺ cells, and less inflammation, demyelination, and axonal damage.

Development

A targeting vector was designed to insert a loxP site followed by an frt-flanked neomycin (neo) resistance cassette upstream of the promoter regions and exon 1, and a second loxP site downstream of exon 1 of the MAD homolog 7 (Smad7) gene. The construct was electroporated into C57BL/6-derived Bruce-4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into CB.20 blastocysts and resulting chimeric mice were bred with B6.Cg-Tg(ACTFLPe)9205Dym/J transgenic mice (Stock No. 005703) to delete the neo cassette. The donating investigator reported that the resulting progeny were crossed to remove the Flp-expressing transgene, resulting in a homozygous Smad7^fl/fl colony (see SNP note below). Males were sent to The Jackson Laboratory Repository in 2013. Upon arrival, males were used to cryopreserve sperm. To establish the living mouse colony, an aliquot of the frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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 first generation rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 4 of 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 C57BL/6J;C57BL/6N genetic background.

Allele

Symbol: Smad7^tm1.1Ink
Name: targeted mutation 1.1, Ingo Kleiter
MGI accession ID: MGI:5426017
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Synonyms: Smad7^fl
Marker symbol: Smad7
Marker name: SMAD family member 7
Marker synonyms: CRCS3; Madh7; MADH8
Chromosome: 18
Strain of origin: B6.Cg-Thy1^a
Molecular note: A targeting vector was designed to insert a loxP site followed by an frt-flanked neomycin (neo) resistance cassette upstream of the promoter regions and exon 1, and a second loxP site downstream of exon 1. Flp-mediated recombination removed the neo cassette and left exon 1 floxed.