STOCK Brca1^tm4.1Rjbr/Mmjax

Stock number: 036740
Product name: Brca1^FH-WT
Strain synonyms: B6;129-Brca1^tm4.1Rjbr/Mmjax
Research areas: Cancer Research, Cell Biology Research

Description

Brca1^FH-WT knock-in mice carry the wild type Brca1 sequence with an epitope tag in the Brca1 (breast cancer 1, early onset) gene. These mice are intended as a control for Brca1^FH-I26A (MMRRC Stock No. 069515) mice, which carry a missense mutation (I26A) in the RING domain and may be useful for studying genome maintenance and breast cancer.

Detailed description

Brca1 (breast cancer 1, early onset) encodes a nuclear phosphoprotein that functions as a tumor suppressor and is involved in maintaining genomic stability.  BRCA1 polypeptides exist as a heterodimeric complex with BARD1, the subsequent heterodimer functions as a ubiquitin E3 ligase.

Brca1^FH-WT knock-in mice carry a wild type Brca1 sequence with FLAG and HA epitope tags. These mice are intended as a control for Brca1^FH-I26A (MMRRC Stock No. 069515) mice, which carry a missense mutation (I26A) in the RING domain. Homozygous mice are viable and fertile. They do not exhibit increased tumor susceptibility.

Development

The Brca1^FH-I26A knock-in allele was created by Dr. Richard Baer at Columbia University. The targeting vector was designed to insert a fragment containing modified exons 1 and 2 with an FRT-flanked promoterless hygromycin resistance sequence in intron 1. Sequence encoding an artificial methionine and the FLAG and HA epitope tags (FH; (MDYKDDDDKYPYDVPDYA) was inserted upstream of the natural translation initiation codon of the Brca1 gene on chromosome 11. Thus, the allele encodes a full-length Brca1 polypeptide (1812 amino acids) fused to an N-terminal FH epitope. The construct was electroporated into 129Sv-derived unspecified embryonic stem (ES) cells. Transient transfection with a Pgk-Flpe plasmid removed the hygromycin cassette. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric animals were bred to C57BL/6 females. Mice were backcrossed to C57BL/6J mice for 4 generations by the donating laboratory (see SNP note below). Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

In 2021, 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 males sent to The Jackson Laboratory Repository. Seven of the 43 markers throughout the genome were segregating with 129, suggesting an incomplete backcross.

Allele

Symbol: Brca1^tm4.1Rjbr
Name: targeted mutation 4.1, Richard J Baer
MGI accession ID: MGI:5494436
Generation method: Targeted
Attributes: Not Applicable
Synonyms: Brca1^FH-WT
Marker symbol: Brca1
Marker name: breast cancer 1, early onset
Marker synonyms: BRCA-1; BRCAI; BRCC1; BROVCA1; FANCS; IRIS; PNCA4; PPP1R53; PSCP; RNF53
Chromosome: 11
Strain of origin: 129
Molecular note: Exon 2 was replaced with a modified exon two containing an artificial initiator methionine, FLAG epitope tag and HA epitope tag. Flp-mediated recombination removed a FRT-flanked hygromycin resistance cassette inserted upstream of the modified exon 2.