Lab Anim Res.  2017 Mar;33(1):1-7. 10.5625/lar.2017.33.1.1.

Over-expression of myosin7A in cochlear hair cells of circling mice

• Kim YY
• Nam H
• Jung H
• Kim B
• Suh JG

• KMID: 2375266
• DOI: http://doi.org/10.5625/lar.2017.33.1.1

Abstract

Circling mouse (C57BL/6J-cir/cir) deleted the transmembrane inner ear (Tmie) gene is an animal model for human non-syndromic recessive deafness, DFNB6. In circling mouse, hair cells in the cochlea have degenerated and hair bundles have become irregularity as time goes on. Tmie protein carries out a function of the mechanoelectrical transduction channel in cochlear hair cells. Myosin7a (MYO7A) protein has key roles in development of the cochlear hair bundles as well as in the function of cochlear hair cells. To find whether Tmie protein interacts with MYO7A proteins in the cochlea postnatal developmental stage, we investigated expression of the MYO7A proteins in the cochlear hair cells of circling mice by western blot analysis and whole mount immunofluorescence at postnatal day 5 (P5). The expression of MYO7A showed statistically significant increase in the cochlea of C57BL/6J-+/cir and C57BL/6J-cir/cir mice than that of C57BL/6J-+/+ mice. The MYO7A intensity of the cochlear hair cells also increased in C57BL/6J-+/cir and C57BL/6J-cir/cir mice compared with those of C57BL/6J-+/+ mice. Taken together, the results indicate that Tmie protein may have an important role with MYO7A protein in the development and maintenance of the stereociliary bundles during postnatal developmental stage of the cochlea.

Keyword

Circling mice; cochlea; transmembrane inner ear (Tmie); myosin7a

MeSH Terms

Animals
Blotting, Western
Cochlea
Deafness
Ear, Inner
Fluorescent Antibody Technique
Hair
Hair Cells, Auditory*
Humans
Mice*
Models, Animal

Figure

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  Figure 1 Genotyping by genomic PCR in the circling mice. A. Location of the primers for genotyping. E: Exon. I: Intron. B. Pedigree of circling mice. Square and circle indicate each male and female. Also empty, compact, and half-and-half indicate C57BL/6J-+/+, C57BL/6J-cir/cir, and C57BL/6J-+/cir, respectively. C. C57BL/6J-+/+ and C57BL/6J-cir/cir mice had the 794 bp and 571 bp bands, respectively. M: Molecular size marker (100 bp DNA ladder).

• 

  Figure 2 Western blot analysis of MYO7A at P5. Proteins isolated from littermate cochlear tissues at P5 used for western blot analysis. Data were analyzed by one-way analysis of variance (ANOVA). Different alphabets indicate statistically significant difference (N=3).

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  Figure 3 Location of MYO7A in cochlear hair cells at P5 by whole mount immunofluorescence. The cochlear hair cells stained with MYO7A antibody (green) and phalloidin (red). Images acquired from the middle cochlear turn. OHC: outer hair cell. IHC: inner hair cell. Scale bar: 5 µm.

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  Figure 4 MYO7A expression in cochlear hair cells at P5 by whole mount immunofluorescence. The cochlear hair cells stained with MYO7A antibody (green) and phalloidin (red). A. Images acquired from parts of the apex, middle, and base cochlear turn. B. MYO7A intensity of the outer hair cells and inner hair cells was measured at parts of the apex, middle, and base of the cochlear duct. Data were analyzed by one-way analysis of variance (ANOVA). Different alphabets indicate statistically significant difference (N=3). OHC: outer hair cell. IHC: inner hair cell. Scale bar: 5 µm.

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