B6(Cg)-Ndnf^{tm1.1(cre/ERT2)Ispgl}/J

Stock number: 034875
Product name: Ndnf-IRES-CreERT2
Research areas: Neurobiology Research, Research Tools

Description

Ndnf-IRES-CreERT2 knock-in mice have a cre/ERT2 fusion gene inserted into the 3' UTR in exon 4 of the neuron-derived neurotrophic factor (Ndnf) gene. These mice retain endogenous Ndnf expression and may be used to generate conditional mutations for studying gain-or-loss of function, fate mapping and/or circuit dissection of NDNF+ cell populations.

Detailed description

Ndnf-IRES-CreERT2 knock-in mice have a cre/ERT2 fusion gene inserted into the 3' UTR in exon 4 of the neuron-derived neurotrophic factor (Ndnf) gene. Ndnf encodes a protein involved in neuron migration, growth and survival as well as neurite outgrowth. Specifically, Ndnf expression is evident in neocortical layer 1 (L1) GABAergic interneurons (INs) in the adult mouse brain, and becomes restricted to GABAergic interneurons only during the third postnatal week. Mice that are homozygous for this knock-in allele are viable and fertile. When Ndnf-IRES-CreERT2 mice are bred with mice containing loxP-flanked sequence(s), tamoxifen-inducible Cre-mediated recombination will result in deletion of the floxed sequence(s) in the Cre-expressing cells of the offspring.

For example, when crossed to Ai9 reporter mice (Stock No. 007909) and tamoxifen is applied after P16, then tdTomato-labeled neurons are found primarily in neocortical L1, with tdTomato expression also seen in blood vessels throughout the cortex. No labeling is observed in the absence of tamoxifen.

Selective labeling of NDNF interneurons in layer 1 without co-labeling of blood vessels can be obtained by using Ndnf-IRES-CreERT2 knock-in mice in combination with AAV-constructs that drive gene expression via neuron-specific promoters (e.g. hSyn1-promoter).

Of note, similar strains are available:
NDNF-Cre knock-in mice from Stock No. 030757 express a constitutively active cre recombinase from the Ndnf promoter.
Ndnf-IRES2-dgCre-D knock-in mice from Stock No. 028536 express a destabilized EGFP/Cre fusion gene (dgCre) driven by the Ndnf promoter.
Ndnf-IRES-FlpO knock-in mice from Stock No. 034876 express a constitutively active flpo recombinase from the Ndnf promoter.

Development

The Ndnf-IRES-CreERT2 targeting vector was designed to insert an internal ribosome entry site (IRES) fused to a cre/ERT2 fusion gene (Cre recombinase fused to a human estrogen receptor ligand binding domain) into the 3' UTR in exon 4 of the neuron-derived neurotrophic factor (Ndnf) gene. The construct also included a frt-flanked neomycin resistance cassette. The construct was electroporated into C57BL/6-derived embryonic stem (ES) cells. Correctly targeted ES cells were injected into blastocysts and resulting chimeric mice were bred with flp recombinase expressing mice on a C57BL/6 genetic background to remove the neo cassette. Resulting Ndnf-IRES-CreERT2 mice were bred to C57BL/6J mice for at least 10 generations. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

Allele

Symbol: Ndnf^{tm1.1(cre/ERT2)Ispgl}
Name: targeted mutation 1.1, Ivo Spiegel
MGI accession ID: MGI:6393601
Generation method: Targeted
Attributes: Recombinase-expressing; Inducible
Synonyms: Ndnf-IRES-CreERT2
Marker symbol: Ndnf
Marker name: neuron-derived neurotrophic factor
Marker synonyms: A930038C07Rik; AABR07060833.1; C4orf31; epidermacan; HH25; NORD; RGD1311080
Chromosome: 6
Strain of origin: C57BL/6J
Site of expression: Expression is evident in neocortical layer 1 (L1) GABAergic interneurons (INs) in the adult mouse brain, and becomes restricted to GABAergic interneurons only during the third postnatal week.
Molecular note: The targeting vector was designed to insert an internal ribosome entry site (IRES) fused to a Cre/ERT2 fusion gene (Cre recombinase fused to a human estrogen receptor ligand binding domain) into the 3' UTR in exon 4 of the neuron-derived neurotrophic factor (Ndnf) gene. The construct also included a frt-flanked neomycin resistance cassette. After homologouse recombination in ES cells, the resulting chimeric mice were bred with flp recombinase expressing mice to remove the neo cassette.