B6.129(Cg)-Ret^tm13Jmi/SjnJ

Stock number: 029846
Product name: Ret^RETfloxEGFP
Research areas: Developmental Biology Research, Neurobiology Research, Research Tools

Description

These RETfloxEGFP mice harbor an EGFP reporter allele with a loxP-flanked human RET cDNA upstream of the enhanced green fluorescent protein (EGFP) gene, which replaces exon 1 of the endogenous Ret gene. After removal of the loxP-flanked human RET cDNA by cre-mediated recombination, EGFP reporter expression is directed to the cells/tissues dependent upon expression of the promoter driving Cre recombinase.

Detailed description

The targeted Ret gene encodes a receptor tyrosine kinase that is important in neural crest and kidney development. Mutations in this gene have been associated with multiple endocrine neoplasia, Hirschsprung disease, and medullary thyroid carcinoma. These mice carry a floxed reporter allele in which exon 1 has been replaced by a vector containing a floxed human RET cDNA and EGFP. Cre recombinase mediated excision of the floxed human RET cDNA results in a null allele and the expression of the EGFP in the cre-expressing tissues. The Donating Investigator reports that homozygous mice are viable and have reduced fertility.

When bred to a strain with Cre recombinase expression in the dopaminergic neurons of the ventral tegmental area and substantia nigra pars compacta (see Stock No. 020080 for example), this mutant mouse strain may be useful in studies of the adult midbrain dopaminergic system.

Development

A targeting vector containing loxP site flanked human RET (ret proto-oncogene) cDNA and SV40 polyadenylation signal, EGFP, and a FRT site flanked neo cassette, was used to disrupt exon 1 of the endogenous Ret gene. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1- Kitl⁺-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts. The resulting chimeric male animals were bred to transgenic mice expressing FLP recombinase, on the C57BL/6 genetic background, to excise the FRT site flanked neo cassette (RETfloxEGFP). The mice were then backcrossed to C57BL/6 for 10 generations and no longer carry the FLP recombinase transgene. 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).

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, all 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 C57BL/6N genetic background.

Allele

Symbol: Ret^tm13Jmi
Name: targeted mutation 13, Jeffrey Milbrandt
MGI accession ID: MGI:3690534
Generation method: Targeted
Attributes: Inserted expressed sequence
Synonyms: Ret^RETfloxEGFP; Ret^tm13(RET)Jmi
Marker symbol: Ret
Marker name: ret proto-oncogene
Marker synonyms: CDHF12; CDHR16; c-Ret; HSCR1; MEN2A; MEN2B; MTC1; PTC; RET51; RET9; RET-ELE1
Chromosome: 6
Strain of origin: (129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Expressed genes: GFP,Green Fluorescent Protein,
Site of expression: Cre recombinase mediated excision of the floxed human RET cDNA results in expression of EGFP in the cre-expressing tissues.
Molecular note: A loxP site and the human RET9 sequence was inserted with a floxEGFPfrt-neo-frt cassette. The neo was removed by FLP mediated recombination. This allele allows EGFP expression upon the cre mediated deletion of floxed RET9 cDNA from exon 1.