B6.129S2-Irs1^smla/J

Stock number: 007240
Research areas: Developmental Biology Research

Description

Homozygotes are small, and only a fraction survive to weaning and breeding age. This strain may be useful in studies of development.

Detailed description

These mice carry a spontaneous nonsense mutation in serine 57 of the Irs1 (insulin receptor substrate 1) gene that, in the homozygous state, produces small mice. Only a fraction of smla homozygotes survive to weaning and breeding age with significant losses beginning at postnatal day 21. Repeated backcrosses to C57BL/6J contributed to marked increases in lethality. Postmortem examination identified no significant gross or microscopic abnormalities aside from proportionally decreased stature and muscle wasting in a subset of mice. Western blot analysis of quadriceps muscle tissue demonstrates no detectable protein in mice homozygous for the mutation.

Development

A spontaneous nonsense C->A point mutation occurred in serine 57 of the Irs1 gene in cultured 129S2/SvPas-derived D3 embryonic stem (ES) cells. ES cell clones were injected into C57BL/6J blastocysts. Mice were mated to B6D2F1 hybrid animals then backcrossed to C57BL/6J six times by the donating investigator.

Allele

Symbol: Irs1^smla
Name: small phenotype
MGI accession ID: MGI:4837622
Generation method: Spontaneous
Attributes: Null/Knockout
Marker symbol: Irs1
Marker name: insulin receptor substrate 1
Chromosome: 1
Strain of origin: 129S2/SvPas
Molecular note: A spontaneous mutation produced a C-to-A transition that results in an amino acid substitution of serine to stop codon at position 57 (p.S57*). The absence of protein expression was confirmed by western blot analysis on muscle extracts.