C57BL/6-Brca1^{tm1.1(BRCA1)Tsr}/J

Stock number: 030081
Product name: Humanized BRCA1 KI
Strain synonyms: Brca1^huBKI/huBKI
Research areas: Cancer Research, Cell Biology Research, Hematological Research, Research Tools

Description

These humanized BRCA1 knock-in mice carry an allele containing human wildtype BRCA1, with a Cre recombinase-inducible mutant 5382insC human BRCA1, from the endogenous mouse Brca1 gene. When bred to mice expressing Cre recombinase, the resulting progeny will express the mutant human 5382insC BRCA1 in the Cre-expressing tissues. These mice are suitable for use in applications related to the study the role of BRCA1 variants in hematopoiesis, hematopoietic stem cell function and chemotherapeutic toxicity.

Detailed description

The targeted Brca1 gene encodes a nuclear phosphoprotein that is critical for maintenance of genomic stability, DNA repair, and cell cycle checkpoint control. These humanized BRCA1 knock-in mice, Brca1^BRCA1/BRCA1, carry a knock-out allele containing human wildtype BRCA1 with a Cre recombinase-inducible mutant 5382insC human BRCA1 expressed from the endogenous mouse Brca1 locus. The expression of human BRCA1 recapitulates endogenous mouse Brca1. When bred to mice expressing Cre recombinase, the resulting progeny will express the mutant human 5382insC BRCA1 in the Cre-expressing tissues. Mice that are homozygous for this targeted mutation are viable and fertile, however in the Jackson Laboratory Repository colony crosses to homozygous males are not productive.

Development

A targeting vector containing (5’ to 3’): human BRCA1 exons 2 to 14 - loxP site - F3 mutant FRT site - Puro cassette - F3 mutant FRT site - human BRCA1 exons 15 to 23 - mouse Brca1 3' UTR - human growth hormone polyadenylation signal - loxP site - human mutant BRCA1 exons 15 to 23 (5382insC point mutation in exon 19) - mouse Brca1 3' UTR - human growth hormone polyadenylation (signal) - FRT - NEO cassette - FRT, was used to replace the coding region in exon 2 and the splice donor-site in intron 2 of the mouse Brca1 gene. The construct was electroporated into C57BL/6NTac-derived ART B6 3.6 embryonic stem (ES) cells, which were transiently transfected with a FLP recombinase vector to remove the selection cassette. ES cells that had successfully undergone FLP-mediated recombination and no longer retained the cassette were injected into blastocysts. The resulting chimeric animals were tested for germline transmission. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).



In 2019 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 rederived living colony at The Jackson Laboratory Repository. While the 43 markers throughout the genome suggested a C57BL/6 genetic background, 3 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: Brca1^{tm1.1(BRCA1)Tsr}
Name: targeted mutation 1.1, Theodora S Ross
MGI accession ID: MGI:5882952
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Null/Knockout; Inserted expressed sequence; Humanized sequence
Synonyms: Brca1^BRCA1
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: C57BL/6NTac
Expressed genes: BRCA1,BRCA1, DNA repair associated,human
Site of expression: Normally expressed in the cells of breast and other tissue; but expression in hematopoietic cells of interest here.
Molecular note: A targeting vector containing (5' to 3'): human BRCA1 exons 2 to 14 - loxP site - F3 mutant FRT site - Puromycin cassette - F3 mutant FRT site - human BRCA1 exons 15 to 23 - mouse Brca1 3' UTR - HGHpA - loxP site - human mutant BRCA1 exons 15 to 23 (including the 5382insC point mutation in exon 19) - mouse Brca1 3' UTR - HGHpA - FRT - NEO cassette - FRT, was used to replace the coding region in exon 2 and the splice donor-site in intron 2 of the mouse Brca1 gene. Transient flp-mediated recombination removed both the puro and neo cassettes.