Allele-specific effects of distinct SLC26A4 variants on cochlear function and transcriptomic programs in compound...

Area of Science:

• Genetics
• Otolaryngology
• Molecular Biology

Background:

• The SLC26A4 gene is a primary cause of hereditary hearing loss, with mutation patterns varying by population.
• Compound heterozygous genotypes are common in Chinese populations, leading to a broad range of auditory symptoms.
• Understanding how different SLC26A4 alleles interact is crucial for explaining hearing loss variability.

Purpose of the Study:

• To investigate the allele-specific mechanisms of two novel SLC26A4 mutations (frameshift and missense) in compound heterozygous contexts.
• To explore how these interactions influence auditory phenotypes, cochlear pathology, and transcriptional changes.

Main Methods:

• In vitro studies using HeLa cells to assess pendrin localization of wild-type and mutant SLC26A4.
• Generation of compound heterozygous knock-in mouse models (Slc26a4^{c.574delC/c.919-2A>G} and Slc26a4^{c.1211C>A/c.919-2A>G}) via CRISPR/Cas9.
• Auditory function assessment (ABR thresholds), cochlear pathology evaluation, and bulk RNA-sequencing for transcriptomic profiling.

Main Results:

• Both novel SLC26A4 mutations reduced membrane localization and increased intracellular retention of pendrin in vitro.
• Compound heterozygous mice showed elevated ABR thresholds, with Slc26a4^{c.574delC/c.919-2A>G} exhibiting more severe hearing loss and cochlear damage.
• Transcriptomic analysis revealed distinct pathway enrichments: structural/developmental in the frameshift model and immune-related in the missense model.

Conclusions:

• Allele-specific functional divergence in compound heterozygous SLC26A4 mutations results in distinct auditory dysfunction and cochlear pathology.
• These findings offer mechanistic insights into the phenotypic heterogeneity observed in SLC26A4-related hearing loss.
• The study suggests potential for allele-specific therapeutic strategies for hereditary hearing loss.