B6.129(Cg)-Ddr2^{tm2.1(cre/Esr1*)Rcow}/J

Stock number: 040879
Product name: Ddr2 mer-iCre-mer
Strain synonyms: Ddr2-creER
Research areas: Cancer Research, Developmental Biology Research, Endocrine Deficiency Research, Research Tools

Description

These Ddr2^mer-iCre-mer knock-in/knock-out mice express tamoxifen-inducible Cre recombinase (MerCreMer) from the mouse Ddr2 promoter in tissues that normally express the Ddr2 gene.

Detailed description

These Ddr2^mer-iCre-mer knock-in/knock-out mice express tamoxifen-inducible Cre recombinase (MerCreMer) from the mouse Ddr2 promoter in tissues that normally express the Ddr2 gene. Expression of Ddr2 is eliminated in the targeted allele. When crossed with Cre-responsive Ai14 tdTomato reporter mice (Stock No. 007914) and with tamoxifen administration, the model enables permanent labeling and lineage tracing of cells that normally express Ddr2 throughout development and postnatal growth. Progeny of this cross that are treated with tamoxifen at P1-P4 mark cells at early stages of bone formation that differentiate to hypertrophic chondrocytes, osteoblasts, and osteocytes. Heterozygous mice are viable and fertile with no observed abnormal phenotype. Mice homozygous for this allele will be global Ddr2-deficient and show skeletal defects. Homozygous males are fertile when young but lose fecundity quickly as they age. And Homozygous females can die unexpectedly during or after birth. The line may be useful for lineage tracing.

Development

An approximately 4.5 kbp cDNA encoding a MerCreMer fusion protein and an FRT-flanked neomycin cassette were recombined in-frame with the Ddr2 ATG start codon (exon 2) via homologous recombination (reference transcript: NM_022563.2). Clones were screened initially by PCR, and the positive clones were verified by Southern blot. The MerCreMer double fusion protein incorporates a cre recombinase cDNA sequence flanked by mutated murine estrogen receptor (mer) ligand binding domains (amino acids 13-331, G257R based on GenBank AAF22561.1). This fusion renders cre expression tamoxifen-inducible and estrogen-insensitive. The targeting vector was linearized and electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl⁺-derived R1 embryonic stem (ES) cells. One targeted clone was microinjected into blastocysts and was implanted into pseudopregnant female hosts. Chimeric pups were bred to C57BL/6J, and agouti pups were screened for the targeted mutation. The resulting mice were crossed with Flpe mice to delete the neomycin cassette. This strain was backcrossed to C57BL/6J for more than 10 generations by the donating laboratory. The mice were previously crossed to mT/mG reporter mice (Stock No. 007676), but the allele was bred out by breeding with C57BL/6J females prior to arrival at The Jackson Laboratory. Upon arrival at The Jackson Laboratory, sperm were cryopreserved. To establish a live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J (Stock No. 000664) oocytes.

Allele

Symbol: Ddr2^{tm2.1(cre/Esr1*)Rcow}
Name: targeted mutation 2.1, Randy T Cowling
MGI accession ID: MGI:5662371
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible; Null/Knockout
Synonyms: Ddr2^mer-iCre-mer; Ddr2-creER
Marker symbol: Ddr2
Marker name: discoidin domain receptor family, member 2
Marker synonyms: DDR2-N; MIG20a; Ntrkr3; TKT; Tyro10; WRCN
Chromosome: 1
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Molecular note: Part of exon two containing the start codon and signal peptide was replaced with two mutated mouse estrogen receptors that sequester cre to the cytoplasm, a polyadenylation sequence, and an FRT-flanked neomycin resistance cassette. Flp-mediated recombination removed the selection cassette.