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Updated: Jun 21, 2026
Evaluation of Planar-Cell-Polarity Phenotypes in Ciliopathy Mouse Mutant Cochlea
Published on: February 21, 2016
Connexin30 null and conditional connexin26 null mice display distinct pattern and time course of cellular
Yu Sun1, Wenxue Tang, Qing Chang
1Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA 30322-3030, USA.
Abstract:
Mutations in connexin26 (Cx26) and Cx30 are the most common cause of nonsyndromic inherited deafness in humans. To understand the underlying molecular mechanisms, we investigated the pattern and time course of cellular degeneration in the cochlea of conditional Cx26 (cCx26) null and Cx30 null mice. In cCx26 null mice, initial degeneration was observed around postnatal day 14 in outer hair cells (OHCs) and supporting cells surrounding the OHCs. All cells in the middle turn organ of Corti were lost 1 month after birth, and degeneration gradually spread to the basal and apical turns. Most spiral ganglion (SG) neurons in the middle and basal turns disappeared in the first 3 months, whereas significant amounts of apical SG neurons survived. In the cochlea of Cx30 null mice, survival of most inner HCs, supporting cells, and SG neurons was observed for up to 18 months. The most severe degeneration was found in apical SG neurons and OHCs. OHC loss followed a slow time course and a base to apex gradient. Gross structures of the endolymphatic space and stria vascularis observed at the light microscope level were unchanged in either Cx null mouse models. This study revealed that cellular degeneration in the cochlea of cCx26 null mice was dramatically more rapid and widespread than that observed in Cx30 null mice. The radically different pathogenesis processes displayed by cCx26 and Cx30 null mice suggest heterogeneous underlying deafness mechanisms, despite co-assembly of Cx26 and Cx30 in forming gap junctions in the cochlea.
Insights
Mutations in connexin26 (Cx26) and connexin30 (Cx30) cause inherited deafness. Cx26 loss leads to rapid cochlear degeneration, while Cx30 loss causes slower, more localized cell loss, suggesting different deafness mechanisms.
Area of Science:
- Genetics
- Neuroscience
- Otolaryngology
Background:
- Mutations in connexin26 (Cx26) and connexin30 (Cx30) are primary genetic causes of human nonsyndromic inherited deafness.
- Understanding the molecular mechanisms of Cx26 and Cx30 in cochlear function is crucial for developing effective treatments.
Purpose of the Study:
- To investigate and compare the cellular degeneration patterns and time courses in the cochlea of conditional Cx26 (cCx26) null and Cx30 null mice.
- To elucidate the distinct pathogenic pathways associated with Cx26 and Cx30 mutations in the inner ear.
Main Methods:
- Generation and analysis of conditional Cx26 null and Cx30 null mouse models.
- Microscopic examination of cochlear cellular degeneration, focusing on hair cells (HCs) and spiral ganglion (SG) neurons.
- Assessment of degeneration patterns over time and across different cochlear turns (base, middle, apex).
Main Results:
- Conditional Cx26 null mice exhibited rapid and widespread degeneration of outer hair cells (OHCs) and supporting cells starting around postnatal day 14, with complete loss in the middle turn within a month.
- Cx30 null mice showed slower degeneration, primarily affecting apical SG neurons and OHCs, with a base-to-apex gradient and significant cell survival for up to 18 months.
- Gross cochlear structures, including the endolymphatic space and stria vascularis, remained largely unchanged in both models.
Conclusions:
- Cx26 and Cx30 null mouse models display markedly different degeneration rates and patterns, indicating distinct molecular mechanisms underlying Cx26- and Cx30-associated inherited deafness.
- Despite their co-assembly into gap junctions, Cx26 and Cx30 play functionally divergent roles in cochlear maintenance, leading to heterogeneous deafness etiologies.
