B6.SJL-Slc6a3^{tm1.1(cre)Bkmn}/J

Stock number: 006660
Product name: DAT^IREScre
Research areas: Cell Biology Research, Neurobiology Research, Research Tools

Description

DAT^IREScre knock-in mice have Cre recombinase expression directed to dopaminergic neurons, without disrupting endogenous dopamine transporter expression. These mice may be useful for studying gene function in dopaminergic neurons, such as drug addiction, Parkinson's disease and Attention Deficit-Hyperactivity Disorder (ADHD).

Detailed description

Mice homozygous for this dopamine transporter IRES-cre (DAT^IREScre) knock-in allele are viable and fertile. Cre recombinase activity is observed as early as embryonic day 15, and co-localizes with endogenous gene expression in adult dopaminergic cell groups (substantia nigra (SN) and ventral tegmental area (VTA), as well as in the retrorubral field). Lesser Cre recombinase activity occurs in adult olfactory bulb glomeruli, mimicking the known lower Slc6a3 (or DAT) expression in this tissue. Although the pattern and intensity of DAT immunostaining in the SN, VTA and striatum do not differ between wild-type and mutant mice, striatum DAT protein levels are moderately reduced (17%) in heterozygotes and significantly reduced (47%) in homozygotes. This diminution in homozygous striatum is associated with significantly increased neuropeptide PDyn (but not D1, D2, or PPE) mRNA levels compared to wild-type, while such an increase is not observed in heterozygotes. When bred with mice containing a loxP-flanked sequence of interest, Cre-mediated recombination will result in deletion of the flanked genome in dopaminergic neurons. As such, these mutant mice may be useful in neurobiological studies to facilitate the analysis of gene function in dopaminergic neurons, such as drug addiction or Parkinson's disease.

In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype could vary from that originally described. The strain description will be modified as published results become available.

Development

To co-express both genes from the endogenous promoter (and minimize interference with endogenous gene function), a targeting vector was designed to insert an internal ribosome entry site-linked Cre recombinase gene (IRES-Cre) and FRT-flanked PGK-neo cassette 23 bp downstream from the stop codon of the endogenous gene. The construct was electroporated into C57BL/6-derived CMT2 embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and chimeric mice were bred to C57BL/6 mice. The FRT-flanked neo cassette was removed in the germline mice by intercrossing with a Flpe-deleter strain on a mixed B6;SJL background (see Stock No. 003800). The resulting mutant offspring (now harboring this DAT^IREScre allele) were maintained on this mixed genetic background prior to arrival at The Jackson Laboratory. Upon arrival, mice were backcrossed to the C57BL/6J inbred strain (Stock No. 000664) for at least five generations.

Allele

Symbol: Slc6a3^{tm1.1(cre)Bkmn}
Name: targeted mutation 1.1, Cristina M Backman
MGI accession ID: MGI:3689434
Generation method: Targeted
Attributes: Recombinase-expressing
Marker symbol: Slc6a3
Marker name: solute carrier family 6 (neurotransmitter transporter, dopamine), member 3
Chromosome: 13
Strain of origin: Not Specified
Expressed genes: cre,cre recombinase,bacteriophage P1
Site of expression: Cre recombinase activity is observed as early as embryonic day 15, and co-localizes with endogenous gene expression in adult dopaminergic cell groups (substantia nigra (SN) and ventral tegmental area (VTA), as well as in the retrorubral field). Lesser Cre recombinase activity occurs in adult olfactory bulb glomeruli, mimicking the known lower Slc6a3 (or DAT) expression in this tissue.
Molecular note: An FRT-flanked neo was removed from the locus, leaving cre recombinase cDNA in the 3' UTR to allow bicistronic mRNA expression.
General note: The targeting vector was electroporated into both R1 and C57BL/6 ES cells.