B6.129-Slc12a6^tm1Garo/J

Stock number: 018982
Research areas: Neurobiology Research, Research Tools

Description

This strain may be useful for generating conditional mutants for applications related to the neurodevelopmental and neurodegenerative disorder called hereditary motor and sensory neuropathy associated with agenesis of the corpus callosum (HMSN/ACC). These mice possess loxP sites flanking exon 18 of the Slc12a6 gene, a K⁺/Cl^- cotransporter associated with HMSN/ACC.

Detailed description

Slc12a6 is a member of the solute carrier family that encodes the K⁺/Cl^- cotransporter 3 (KCC3 or SLC12A6). KCC3 has a role in ion homeostasis and is associated with the neurodevelopmental and neurodegenerative disorder called hereditary motor and sensory neuropathy associated with agenesis of the corpus callosum (HMSN/ACC). Most HMSN/ACC patients carry a deletion in exon 18 (a conserved splice donor site) that results in a stop codon at position 813 (Thr813X). KCC3 is expressed in brain, kidney, muscle lung and heart.

These mutant mice possess loxP sites flanking exon 18 of the Slc12a6 gene. Mice that are homozygous for this allele are viable and fertile. When bred to mice that express Cre recombinase, the resulting offspring will have exon 18 deleted in the cre-expressing tissues resulting in a C terminal truncation of the protein mimicking the human HMSN/ACC mutation. These mice may be useful in generating conditional knockouts for studying the role of KCC3 in the central and peripheral nervous systems.

For example, when bred to mice carrying Tg(Syn1-cre)671 Jxm (see Stock No. 003966), Cre recombinase expression in neuronal cells results in hyperactivity, reduced pain sensitivity, axonal degeneration, axon swelling, and hypoplasia of the corpus callosum.

Development

A targeting vector was designed to insert a a frt-flanked neomycin resistance (neo) cassette and a loxP site upstream of exon 18 and a second loxP site downstream of exon 18. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts and the resulting chimeric mice were crossed to C57BL/6 mice to establish the colony. Mutant mice backcrossed with C57BL/6 inbred mice for at least six generations were sent to The Jackson Laboratory Repository in 2012 (see SNP results below). Upon arrival, males were used to cryopreserve sperm. To establish the living mouse colony, an aliquot of the frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).

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 first generation 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: Slc12a6^tm1Garo
Name: targeted mutation 1, Guy A Rouleau
MGI accession ID: MGI:5318538
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Slc12a6
Marker name: solute carrier family 12, member 6
Chromosome: 2
Strain of origin: 129
Molecular note: An FRT and LoxP flanked neo cassette was inserted upstream of exon 18 and a loxP site was inserted downstream of exon 18 via homologous recombination.