STOCK Calcr^{tm1.1(cre)Mgmj}/J

Stock number: 037028
Product name: Calcr-Cre
Research areas: Neurobiology Research, Research Tools

Description

Calcr^Cre mice have the endogenous calcitonin receptor (Calcr) promoter/enhancer sequences directing expression of Cre recombinase. These mice are a Cre-lox tool allowing Cre recombination in Calcr-expressing cells/tissues (including neurons of the nucleus of the solitary tract, hypothalamus, and lateral reticular nucleus) and may be useful for studying feeding behavior, obesity, and metabolism.

Detailed description

The Calcr gene encodes encodes the calcitonin receptor, which is involved in skeletal development .

The Calcr^Cre knock-in allele has as IRES enhancer sequence and a Cre recombinase inserted downstream of the Calcr translational STOP codon. This is designed to have the endogenous Prlh promoter/enhancer elements directing cre expression primarily in the arcuate nucleus of the hypothalamus (see below), as well as to retain endogenous Calcr expression. Specific details are below.

The donating investigator reports that when crossed to GFP-expressing Cre-reporter mice (such as Stock No. 024750), GFP expression can be observed in several hypothalamic regions including the arcuate and dorsomedial nuclei, lateral hypothalamic area, and nucleus of the solitary tract (Pan et al., 2018).
Furthermore, when crossed with Prlh-floxed mice (Stock No. 036748), the resulting Prlh^CalcrKO mice exhibit an age-dependent increase in body weight when fed high-fat chow (Cheng et al., 2021).

Development

The Calcr^cre knock-in allele was created in the laboratory of Dr. Martin Myers (University of Michigan) to have a T2A sequence and a Cre recombinase gene inserted immediately downstream of the calcitonin receptor locus (Calcr) on chromosome 6. The specific details are below.

To generate Calcr^cre mice, a selection cassette containing the porcine teschoviral 2A cleavage sequence (T2A) linked to Cre recombinase and an FRT-flanked neomycin resistance gene was targeted to replace the stop codon of the Calcr gene in a bacterial artificial chromosome (RP24-193M22). A targeting plasmid containing the Cre-containing selection cassette and ~4-kb genomic sequence upstream and downstream of the Calcr stop codon was isolated and used for embryonic stem cell targeting. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl⁺-derived R1 ES cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric mice were bred with C57BL/6J for germline transmission. Offspring were bred with Flpo-expressing mice (ROSA26-FLPo on a C57BL/6J background; Stock No. 012930) for germline deletion of the PGK-neo-polyA cassette. The resulting Calcr^cre colony had the Flpo-expressing allele removed and were subsequently bred to mice carrying other contaminating alleles (mixed genetic background; see SNP note). These alleles were either removed prior to sending males to The Jackson Laboratory Repository or were removed during rederivation of a clean colony. To establish our live colony, the strain was bred at least one generation to C57BL/6J (Stock No. 000664).

In 2022, 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. The results suggests a mixed genetic background consisting of C57BL/6 (substrains C57BL/6J and C57BL/6N) and 129, as well as some other unknown contribution at the MHC on chromosome 17 (possibly CBA, C3H, FVB, SJL or other).

Allele

Symbol: Calcr^{tm1.1(cre)Mgmj}
Name: targeted mutation 1.1, Martin G Myers, Jr
MGI accession ID: MGI:6719375
Generation method: Targeted
Attributes: Recombinase-expressing
Synonyms: Calcr^cre
Marker symbol: Calcr
Marker name: calcitonin receptor
Marker synonyms: Clr; CRT; CTR; CT-R; CTR1
Chromosome: 6
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Molecular note: A targeting plasmid containing the porcine teschoviral 2A cleavage sequence linked to Cre recombinase and a Frt-flanked neomycin resistance gene replacing the stop codon of the Calcr gene in a bacterial artificial chromosome (RP24-193M22) was used for embryonic stem cell targeting. Chimeric animals generated were mated to Flp-deleter mice to remove the neomycin selection cassette.