C57BL/6-Tg(Adipoq-icre/ERT2)1Soff/J

Stock number: 025124
Research areas: Metabolism Research, Research Tools

Description

These transgenic mice express a tamoxifen-inducible codon-improved Cre recombinase, iCre-ERT2, under the control of the Adipoq gene promoter. They may be useful in generating adipocyte-specific targeted mutants in studies related to adipose tissue function and storage, obesity, and other metabolic diseases.

Detailed description

Mice hemizygous for this Adipoq-CreERT2 BAC transgene are viable and fertile, with expression of a tamoxifen inducible codon-improved Cre recombinase (icre/ERT2) directed to adipose tissue by the promoter/regulatory regions of the mouse adiponectin (Adipoq) locus on the BAC transgene. When crossed with a Rosa26LacZ reporter tamoxifen induced Cre recombination is detected in 97%–99% of adipocytes in white adipose tissue and approximately 15% of adipocytes in brown adipose tissue. No tamoxifen induced Cre recombination is detected in liver, pancreas, gut, kidney, lung, aorta, skeletal muscle, heart, spleen, thymus, cerebrum, or cerebellum. Cre recombinase activity is not detected in the absence of tamoxifen.

The Cre-ERT2 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-ERT2 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 construct containing sequence encoding iCre-ERT2 fusion protein and a FRT site flanked ampicillin resistance cassette was utilized to generate this mutant strain. The mouse bacterial artificial chromosome (BAC) BAC RP23-112M7, containing the entire Adipoq gene (as well as Kng1, Eif4a2, and Rfc4), was modified by insertion of this targeting vector into the start codon of Adipoq. The FRT flanked selection cassette by excised by Flp recombinase. A transgenic construct was generated from the modified BAC and microinjected into C57BL/6 oocytes. Founder line 1 was subsequently established. The donating investigator reported that the mice were then backcrossed to C57BL/6 for 13 generations (see SNP note below). Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.

A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 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 27 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: Tg(Adipoq-icre/ERT2)1Soff
Name: transgene insertion 1, Stefan Offermanns
MGI accession ID: MGI:4946615
Generation method: Transgenic
Attributes: Recombinase-expressing; Inducible
Marker symbol: Tg(Adipoq-icre/ERT2)1Soff
Marker name: transgene insertion 1, Stefan Offermanns
Chromosome: UN
Strain of origin: C57BL/6
Expressed genes: cre/ERT2,Cre recombinase and estrogen receptor 1 (human) fusion gene,
Site of expression: lacZ is expressed in epididymal, mesenterial, and retroperitoneal white adipose tissue after tamoxifen treatment.
Molecular note: A targeting vector containing cDNA encoding icre fused to the mutated form of the ligand-binding domain of the human estrogen receptor followed by an Frt-flanked ampicillin resistance marker was generated. Homologous recombination resulted in the insertion of the vector into the start codon of the Adipoq locus present in a BAC clone (RP23-112M7; this BAC also contained the genes Kng1, Eif4a2, and Rfc4.) Flp-mediated excision removed the ampicillin marker. Five founders were obtained and crossed with lacZ reporter mice. Progeny of one founder displayed homogeneous lacZ expression in epididymal, mesenteric, and retroperitoneal white adipose tissue after tamoxifen treatment.