B6;129X1-Cldn6^{tm1(cre/ERT2)Dam}/J

Stock number: 014638
Research areas: Research Tools

Description

In this strain the entire coding region of the Cldn6 gene is replaced with a CreER^T2 fusion protein, an internal ribosome entry site (IRES) and a histone H2B-Venus fluorescent protein. These mice may be useful for visualizing endoderm specification, proliferation, and patterning in the developing embryo.

Detailed description

In this strain, the Cldn6^CIHV allele replaces the entire coding region of the claudin 6 (Cldn6) locus with a CreER^T2 fusion protein, an internal ribosome entry site (IRES), and a histone H2B-Venus fluorescent protein. This abolishes gene expression. Homozygotes are viable, fertile, normal in size, and do not display any gross physical or behavioral abnormalities. CLDN6 is a structural protein involved in tight junction formation, with a functional role in the epidermal permeability barrier. In this strain endogenous Cldn6 promoter/enhancer regions drive Cre-ER^T2 expression and Venus immunofluorescence in embryonic endoderm during organogenesis. Cre-ER^T2 fusion gene activity is inducible and only observed following tamoxifen administration. When Cldn6^CIHV mice are bred with mice containing loxP-flanked sequence, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the floxed sequences in the Cldn6-expressing cells of the offspring. These mice may be useful for visualizing endoderm specification, proliferation, and patterning in the developing embryo.

The Cre-ER^T2 fusion protein consists of Cre recombinase fused to a triple mutant form of the human estrogen receptor which does not bind its natural ligand (17β-estradiol) at physiological concentrations but will bind the synthetic estrogen receptor ligands 4-hydroxytamoxifen (OHT or tamoxifen) and, with lesser sensitivity, ICI 182780. Restricted to the cytoplasm, Cre-ER^T2 can only gain access to the nuclear compartment after exposure to tamoxifen. To counteract the mixed estrogen agonist effects of tamoxifen injections, which can result in late fetal abortions in pregnant mice, progesterone may be coadministered.

Development

A targeting vector was designed to replace the entire coding sequence of the claudin 6 (Cldn6) gene with, from 5' to 3', a CreER^T2 fusion protein, an internal ribosome entry site (IRES), a histone H2B-Venus fluorescent protein, an SV40 polyadenylation signal, and a self-excising ACN neomycin (neo) selection cassette. This construct was electroporated into 129X1/SvJ-derived AV3 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts and chimeric males were bred with C57BL/6J females. These Cldn6^CIHV mutant mice were maintained on this mixed B6;129X1 genetic background. Upon arrival at The Jackson Laboratory, mice were bred with C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.

Allele

Symbol: Cldn6^{tm1(cre/ERT2)Dam}
Name: targeted mutation 1, Douglas A Melton
MGI accession ID: MGI:3772092
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible
Synonyms: Cldn6^{tm1(cre/ESR1)Dam}; Cldn6^CIHV
Marker symbol: Cldn6
Marker name: claudin 6
Chromosome: 17
Strain of origin: 129X1/SvJ
Expressed genes: cre/ERT2,Cre recombinase and estrogen receptor 1 (human) fusion gene,
Site of expression: Cre-ERT2 expression and Venus immunofluorescence is seen in embryonic endoderm during organogenesis.
Molecular note: The entire reading frame contained within exon 3 was replaced with the CIHV cassette that contains cre-ER, IRES, HIST2H2BE-Venus and a self-excising neo cassette. The absence of transcript was confirmed by in situ hybridization. This allele also functions as a reporter.