B6;129S1-Smc1a^tm1Mbk/J

Stock number: 013122
Product name: Smc1^S957AS966A
Research areas: Cell Biology Research

Description

This strain contains mutations in exon 19 of the endogenous structural maintenance of chromosomes 1A Smc1a gene. These mice may be useful for studying cell survival and chromosomal stability after DNA damage.

Detailed description

This strain contains mutations in exon 19 of the endogenous structural maintenance of chromosomes 1A, Smc1a, gene. Serine to Alanine mutations in amino acid residues 957 and 966 of exon 19 abolish both of the damage-induced phosphorylation sites of Smc1a. Homozygous Smc1^S957AS966A mice are viable, fertile, and normal in size. Cells from these mice show normal aggregation of Nibrin (NBS1) and breast cancer 1 (BRCA1) proteins, and normal activation and migration of Ataxia Telangiectasia, mutated (ATM) at the site of DNA breaks, all of which are required for Smca1 phosphorylation. Smca1 is not phosphorylated in fibroblasts from these mice, they exhibit a defective S-phase checkpoint, decreased survival, and increased chromosomal aberrations and radiosensitivity after DNA damage. These mice may be useful for studying cell survival and chromosomal stability after DNA damage.

Development

A targeting construct was made containing exons 17-19 of the mouse structural maintenance of chromosomes 1A (Smc1a) gene. Amino acid residues 957 and 966 in exon 19 were both changed from a Serine to an Alanine. The targeting vector also contained a loxP-flanked neo cassette. This targeting construct, designed to replace the endogenous exon 19 of the mouse Smc1a gene with one lacking both of the damage-induced phosphorylation sites, was electroporated into 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺-derived W9.5 embryonic stem (ES) cell line. Correctly targeted ES cells were transiently transfected with a pMC-Cre Cre-recombinase expression plasmid to delete the neo cassette. Correctly targeted ES cells were injected into C57BL/6 blastocysts and the resulting chimeric males were bred to C57BL/6J females. These Smc1^S957AS966A mice were maintained on a mixed background. Upon arrival at The Jackson Laboratory, mice were bred to C57BL/6J (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Smc1a^tm1Mbk
Name: targeted mutation 1, Michael B Kastan
MGI accession ID: MGI:3612278
Generation method: Targeted
Marker symbol: Smc1a
Marker name: structural maintenance of chromosomes 1A
Chromosome: X
Strain of origin: 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺
Molecular note: Two serines were mutated to alanines at positions 957 and 966 in exon 19.