129S/Sv-Cdh23^tm1.1Kjn/Kjn

Stock number: 016208
Research areas: Sensorineural Research

Description

This strain has an A to G point substitution in Cdh23 that is equivalent to the age related hearing loss (Cdh23^ahl) mutation and causes mice that are predominantly 129S1/SvImJ to have the age related hearing loss phenotype that is normally found instead in inbred strains bearing the Cdh23^ahl mutation, such as C57BL/6J and C57BL/6NJ.

Detailed description

The introduction of this c.753A point mutation in Cdh23 causes age related hearing loss that is more severe than the phenotype of C57BL/6J, a strain that also has the Cdh23 c.753A variant. At 30 days of age, the earliest time point assessed, ABR thresholds show significant deficits at 8 kHz and 16 kHz and complete deafness at 32 kHz. This increased severity is attributable to the different genetic background, including the presence of the 129S allele of the Mahl QTL. The progressive inner and outer cochlear hair cell loss is also more severe than that found in the Cdh23^ahl congenic strain that additionally carries the C57BL/6J allele of Mahl (see Stock No. 018926). Genotyping assay details for distinguishing the targeted 753A SNV allele from non-engineered alleles can be found in Johnson et al., 2017, Sci Rep 7:44450.

Development

The sequence of Chromosome 10 from 60,527,162 bp through 60,536,889 bp (GRCm38), which contains the c.753A mutation called age related hearing loss (Cdh23^ahl), was cloned from a C57BL/6J-derived BAC, a loxP-flanked PGK-Neo cassette was then inserted 178 bp downstream of the c.753A nucleotide, and homology arms were added to correctly target this sequence to replace the endogenous coding sequence via homologous recombination in 129S1-derived CJ7 ES cells. This resulted in an G to A point mutation, which effectively recapitulates the Cdh23^ahl mutation but on a 129S1 background. Founders were bred to 129S/Sv-Tg(Prm-cre)58Og/J to excise the downstream loxP-flanked PGK-Neo cassette and their offspring were bred to 129S1/SvImJ to remove the transgene. Mice heterozygous for this point substitution were intercrossed to homozygosity.

Allele

Symbol: Cdh23^tm1.1Kjn
Name: targeted mutation 1.1, Kenneth R Johnson
MGI accession ID: MGI:5897899
Generation method: Targeted
Attributes: Not Specified
Marker symbol: Cdh23
Marker name: cadherin 23 (otocadherin)
Chromosome: 10
Strain of origin: 129S1/Sv-Oca2⁺ Tyr⁺ Kitl⁺
Molecular note: Chr10: 60,527,162 bp 60,536,889 bp (GRCm38), which contains the c.753A point mutation but is otherwise identical in sequence to the 129S1/SvImJ sequence, was taken from a C57BL/6J-derived BAC, a loxP-flanked PGK-Neo cassette was inserted 178 bp downstream of the c.753 nucleotide, homology arms were added to correctly target this sequence to replace the endogenous coding sequence, resulting in a G to A point substitution with a loxP-flanked PGK-Neo cassette. Subsequent breeding to a cre deleter strain excised the selection cassette and generated this allele. Cochlear transcripts show increased exon skipping as a result of this point mutation, and this is predicted to delete part of the 2nd and 3rd ectodomains.