B6(129X1)-Ighg1^{em1(cre/ERT2)Rsky}/J

Stock number: 032860
Product name: Cγ1-CreERT2
Research areas: Immunology, Inflammation and Autoimmunity Research, Research Tools

Description

Cγ1-CreERT2 knock-in mice have a cre/ERT2 fusion gene inserted into the 3’ UTR of the immunoglobulin heavy constant gamma 1 (G1m marker) (Ighg1) gene. These mice are useful when studying normal and malignant germinal center B cell development in vivo.

Detailed description

CRISPR/cas9 endonuclease mediated genome editing of the immunoglobulin heavy constant gamma 1 (Ighg1; aka Cγ1) gene was used to insert a cre/ERT2 fusion gene into the 3' UTR in these Cγ1-CreERT2 knock-in mice. Cγ1 is expressed by germinal center and post-germinal center B cells. Mice that are homozygous for this allele are viable and fertile. When bred with mice containing loxP-flanked sequence, tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequence in a small subset of germinal center B cells. These mice are useful when studying normal and malignant germinal center B cell development in vivo.

Of note, the donating investigator has donated similar strains including Cγ1-cre mice (Stock No. 010611) and Cγ1-CDE mice with Cre and dre/ERT2 expression as Stock No. 040961.

Development

Single guide RNAs and a targeting vector, designed to insert an internal ribosomal entry site (IRES) followed by a cre/ERT2 fusion gene (Cre recombinase fused to a mutated human estrogen receptor ligand-binding) into the 3’ untranslated region of the immunoglobulin heavy constant gamma 1 (Ighg1) gene, and the Cas9 nuclease were introduced into the cytoplasm of C57BL/6NCrl fertilized eggs with well recognized pronuclei. One correctly targeted pup was identified by PCR and Southern blot and was were further bred to R26-stop-EYFP reporter mice (Stock No. 006148) to develop a homozygous colony of Cγ1-CreERT2 knock-in mice carrying a copy of R26-stop-EYFP. The R26-stop-EYFP was bred out of the colony by the donating lab prior to sending the mice to The Jackson Laboratory. 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).

Of note, the ampicillin resistance cassette from the targeting event is still present in this strain.

Allele

Symbol: Ighg1^{em1(cre/ERT2)Rsky}
Name: endonuclease-mediated mutation 1, Klaus Rajewsky
MGI accession ID: MGI:6266867
Generation method: Endonuclease-mediated
Attributes: Recombinase-expressing; Inducible
Synonyms: Cgamma1-CreERT2
Marker symbol: Ighg1
Marker name: immunoglobulin heavy constant gamma 1 (G1m marker)
Marker synonyms: IgG1; IgG3; Igh-4
Chromosome: 12
Strain of origin: C57BL/6NCrl
Site of expression: Germinal center and post-germinal center B cells.
Molecular note: Single guide RNAs and a targeting vector, designed to insert an internal ribosomal entry site (IRES) followed by a cre/ERT2 fusion gene into the 3' untranslated region of the immunoglobulin heavy constant gamma 1 (Ighg1) gene, and the Cas9 nuclease were introduced into the cytoplasm of C57BL/6NCrl fertilized eggs with well recognized pronuclei.