Effects of Cdh23 single nucleotide substitutions on age-related hearing loss in C57BL/6 and 129S1/Sv mice and comparisons with congenic strains

Kenneth R Johnson,Dalian Ding,Richard Salvi,Haiyan Jiang,Cong Tian,Leona H Gagnon

doi:10.1038/srep44450

Kenneth R Johnson, Dalian Ding + Show 4 more

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https://doi.org/10.1038/srep44450

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Abstract

A single nucleotide variant (SNV) of the cadherin 23 gene (Cdh23c.753A), common to many inbred mouse strains, accelerates age-related hearing loss (AHL) and can worsen auditory phenotypes of other mutations. We used homologous recombination in C57BL/6 NJ (B6N) and 129S1/SvImJ (129S1) embryonic stem cells to engineer mouse strains with reciprocal single base pair substitutions (B6-Cdh23c.753A>G and 129S1-Cdh23c.753G>A). We compared ABR thresholds and cochlear pathologies of these SNV mice with those of congenic (B6.129S1-Cdh23Ahl+ and 129S1.B6-Cdh23ahl) and parental (B6N and 129S1) strain mice. Results verified the protective effect of the Cdh23c.753G allele, which prevented high frequency hearing loss in B6 mice to at least 18 months of age, and the AHL-inducing effect of the Cdh23c.753A allele, which worsened hearing loss in 129S1 mice. ABR thresholds differed between 129S-Cdh23c.753A SNV and 129S1.B6-Cdh23ahl congenic mice, and a linkage backcross involving these strains localized a Chr 10 QTL contributing to the difference. These results illustrate the large effects that strain background and congenic regions have on the hearing loss associated with Cdh23c.753alleles. Importantly, the B6-Cdh23c.753Gstrain can be used to eliminate the confounding influence of the Cdh23c.753Avariant in hearing studies of B6 mice and mutant mice on the B6 background.

Highlights

Age-related hearing loss (AHL) is the most prevalent sensory impairment in elderly individuals and is becoming a major health concern with world population aging[1]
Full strain nomenclature and Jackson Laboratory stock numbers are given in Table 1 for the abbreviated strain designations used . 129S1 and B6 embryonic stem (ES) cells were used in a recombineering approach to create the 129S-Cdh23c.753A and B6-Cdh23c.753G single nucleotide variant (SNV) strains (Fig. 1), and the targeted single nucleotide substitutions in these strains were verified by DNA sequence analysis (Fig. 2A)
Our results using homologous recombination in ES cells to produce single base pair substitutions in Cdh[23] add to the evidence from recent in vivo CRISPR-Cas[9] gene editing studies[16,17] showing that Cdh23c.753A is the causative variant responsible for the age-related hearing loss effects ascribed to the Chr 10 ahl locus

Summary

Introduction

Age-related hearing loss (AHL) is the most prevalent sensory impairment in elderly individuals and is becoming a major health concern with world population aging[1]. The coincident map position of ahl with cadherin 23 (Cdh23) and the correspondence of specific Cdh[23] alleles with hearing loss severity in multiple inbred strains provided evidence that a single nucleotide variant (SNV) of Cdh[23] underlies the ahl phenotype[14]. We describe our analyses of C57BL/6NJ mice with a Cdh23c.753A>G single nucleotide substitution and 129S1/SvImJ mice with the reciprocal Cdh23c.753G>A substitution produced by means of the traditional targeting approach using homologous recombination in embryonic stem (ES) cells These strains were chosen because of their widespread use and the availability of strain-matched ES cells and BAC clones. Our results provide insight into the genetic and pathological mechanisms underlying progressive hearing loss in these two commonly used inbred strains of mice with potential implications for human genetic studies of age-related hearing loss

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