STOCK Ntrk2^tm1Ddg/J

Stock number: 022363
Research areas: Cell Biology Research, Neurobiology Research, Research Tools

Description

These mice carry a floxed F616A mutation in mouse Ntrk2 (neurotrophic tyrosine kinase, receptor, type 2; also called TrkB). Signaling is effectively blocked by application of 1NMPP1. This strain is useful in studies of nerve growth and survival.

 

Detailed description

Ntrk2 (neurotrophic tyrosine kinase, receptor, type 2; also called TrkB) is a receptor for brain derived neurotrophic factor (Bdnf), a neurotrophin which controls aspects of mammalian nervous system development.

These mice carry a floxed F616A mutation in exon 14 of the mouse Ntrk2 gene. The allele is sensitive to a family of small-molecule inhibitors including 1NaPP1 and 1NMPP1 which act selectively, rapidly and reversibly. Without 1NaPP1 or 1NMPP1 application, no apparent phenotype is observed in the mice. In cortical neurons cultured from mutant mice, BDNF induced NTRK2 phosphorylation and its downstream signaling events are robustly and specifically blocked by nanomolar concentrations of 1NMPP1 or 1NaPP1. These compounds do not block wild-type signaling. 1NMPP1 application during pregnancy leads to a 50% reduction in the number of nodose ganglion neurons. 1NMPP1 treatment during adulthood leads to degeneration of selective motor neuron terminals.

Development

An 11.2kb BsrBI fragment containing exon 15 of the gene was isolated from a 129S6/SvEvTac mouse genomic BAC library (RPCI-22). Site-directed mutagenesis was used to produce the F616A point mutation. The targeting vector was comprised of a 0.7kb short arm, a 7.3kb long arm, and the 3.2kb targeted sequence containing the loxP-exon 15 F616A-FRT-neo-FRT-loxP construct. Original NCBI/Ensembl data indicated exon 14 as the target, however current data indicate that the target was exon 15. Heterozygotes were bred with C57BL/6-backcrossed mice bearing Tg(ACTFLPe)9205Dym to excise the FRT-flanked neomycin cassette. The donating investigator reported that this strain was backcrossed to C57BL/6 for approximately 6 generations (see SNP note below).

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. Two of the 27 markers throughout the genome suggested 129 was still present in the background. One of 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 mixed C57BL/6J ; C57BL/6N genetic background.

Allele

Symbol: Ntrk2^tm1Ddg
Name: targeted mutation 1, David D Ginty
MGI accession ID: MGI:3583735
Generation method: Targeted
Attributes: Not Specified
Marker symbol: Ntrk2
Marker name: neurotrophic tyrosine kinase, receptor, type 2
Chromosome: 13
Strain of origin: 129P2/OlaHsd
Molecular note: A phenylalanine to alanine substitution mutation at residue 616 (F616A) was introduced via homologous recombination using a mutagenized construct with an FRT flanked neomycin resistance tag. Heterozygotes were bred with mice bearing Tg(ACTFLPe)9205Dym which expressed FLP1 recombinase. The resulting allele has the F616A mutation but the neomycin resistance cassette has been excised.