B6.129(FVB)-Igf1^tm1Dlr/J

Stock number: 016831
Product name: Igf1^flox
Research areas: Research Tools

Description

These floxed mutant mice possess loxP sites flanking exon 4 of the Igf1 gene and a neomycin resistance (neo) cassette. This strain may be useful for studying postnatal growth and development.

Detailed description

These mutant mice feature loxP sites flanking exon 4 of the insulin-like growth factor 1 (Igf1) gene and a neomycin resistance cassette. Homozygotes for this allele are viable, fertile, and normal in size. IGF1 promotes cell survival and cell proliferation by activating the tyrosine kinase transmembrane receptor, IGF-1R. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have exon 4 deleted in cre-expressing tissues. For example, when these mice are bred to Tg(Alb1-cre)1Dlr/J mice (Stock No. 016832 or Stock No. 016833), IGF1 expression is abolished in liver. This strain may be useful for studying postnatal growth and development.

When bred to a strain expressing Cre recombinase in the early mouse embryo (see Stock No. 003724 for example), this mutant mouse strain may be useful in studies of early development.

Development

A targeting vector was designed to insert a loxP site upstream of exon 4 and a neomycin resistance (neo) cassette and second loxP site downstream of exon 4 of the insulin-like growth factor 1 (Igf1) gene. The construct was electroporated into 129-derived embryonic stem (ES) cells, and correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric males were bred with C57BL/6J females, and their offspring were subsequently crossed to FVB-Tg(Alb1-cre)1Dlr mice. The donating investigator reported that these mice were backcrossed to C57BL/6J inbred mice for at least 9 generations (see SNP note below). Upon arrival, the mice were bred to C57BL/6J inbred mice (Stock No. 000664) for one generation and transgene was selectively bred out of the line.

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 rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, all 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 C57BL/6N genetic background.

Allele

Symbol: Igf1^tm1Dlr
Name: targeted mutation 1, Derek LeRoith
MGI accession ID: MGI:2152423
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Igf1
Marker name: insulin-like growth factor 1
Chromosome: 10
Strain of origin: 129
Molecular note: A neomycin cassette and loxP sites were inserted flanking exon 4. The introduction of these mutations had no effect on the normal function of the gene.
General note: ES cells = 129/Sv