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A point mutation in a plasma membrane Ca(2+)-ATPase gene causes deafness in Wriggle Mouse Sagami
1Department of Otolaryngology, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi, Tochigi, 329-0498, Japan. takamasa@jichi.ac.jp
Abstract:
The spontaneous mutant, Wriggle Mouse Sagami (wri), is thought to be a model of hereditary hearing losses in humans. Here we report that the plasma membrane Ca(2+)-ATPase type 2 (PMCA2) gene is mutated in the wri mouse. A G-to-A transition was detected in wri, changing Glu-to-Lys within a conserved transmembrane domain. Mutation of PMCA2 was previously reported in deafwaddler (dfw) mutants; however, the sites of the wri and dfw mutations differ. Immunohistochemical analysis demonstrated that PMCA2 labeling in stereocilia of the cochlea was absent in the wri mutant, suggesting that PMCA2 is crucially involved in the physiology of the auditory system.
Insights
The Wriggle Mouse Sagami (wri) mutation reveals a new cause of hereditary hearing loss. This study identifies a mutation in the plasma membrane Ca(2+)-ATPase type 2 (PMCA2) gene, crucial for auditory system function.
Area of Science:
- Genetics
- Neuroscience
- Otolaryngology
Background:
- The Wriggle Mouse Sagami (wri) mutant is a potential model for human hereditary hearing loss.
- The plasma membrane Ca(2+)-ATPase type 2 (PMCA2) gene is essential for calcium homeostasis.
- Previous studies linked PMCA2 mutations to hearing loss in other mouse models, like deafwaddler (dfw).
Purpose of the Study:
- To identify the genetic basis of hearing loss in the wri mouse mutant.
- To investigate the role of PMCA2 in auditory physiology.
Main Methods:
- Genetic sequencing to identify mutations in the wri mouse.
- Immunohistochemical analysis of PMCA2 expression in cochlear stereocilia.
Main Results:
- A specific G-to-A transition mutation was found in the PMCA2 gene of wri mice, altering an amino acid in a transmembrane domain.
- PMCA2 protein labeling was absent in the stereocilia of the wri mutant's cochlea.
- The mutation site in wri differs from the previously identified dfw mutation site.
Conclusions:
- The PMCA2 gene mutation is responsible for the hearing loss phenotype in wri mice.
- PMCA2 is critically involved in the function of the auditory system, specifically within cochlear stereocilia.
- This finding provides new insights into the genetic causes of hereditary hearing loss.