Targeted connexin26 ablation arrests postnatal development of the organ of Corti
Yunfeng Wang1, Qing Chang, Wenxue Tang
1Department of Otolaryngology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322-3030, USA.
Abstract:
Mutations in the gene coding for connexin26 (Cx26) is the most common cause of human nonsyndromic hereditary deafness. To investigate deafness mechanisms underlying Cx26 null mutations, we generated three independent lines of conditional Cx26 null mice. Cell differentiation and gross cochlear morphology at birth seemed normal. However, postnatal development of the organ of Corti was stalled as the tunnel of Corti and the Nuel's space were never opened. Cell degeneration was first observed in the Claudius cells around P8. Outer hair cell loss was initially observed around P13 at middle turn when inner hair cells were still intact. Massive cell death occurred in the middle turn thereafter and gradually spread to the basal turn, resulting in secondary degeneration of spiral ganglion neurons in the corresponding cochlear locations. These results demonstrated that Cx26 plays essential roles in postnatal maturation and homoeostasis of the organ of Corti before the onset of hearing.
Insights
Connexin26 (Cx26) mutations cause hereditary deafness. Cx26 null mice show stalled cochlear development and cell death, revealing Cx26
Area of Science:
- Genetics
- Otolaryngology
- Developmental Biology
Background:
- Mutations in the connexin26 (Cx26) gene are the leading cause of human nonsyndromic hereditary deafness.
- Understanding the precise mechanisms of Cx26-related hearing loss is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the functional roles and developmental impact of connexin26 (Cx26) in the inner ear.
- To elucidate the cellular and molecular mechanisms underlying hearing loss in Cx26 null mutations.
Main Methods:
- Generation of three independent lines of conditional Cx26 null mice.
- Histological and morphological analysis of cochlear development and cell survival at various postnatal stages.
Main Results:
- Postnatal development of the organ of Corti was arrested in Cx26 null mice, with failure of key spaces (tunnel of Corti, Nuel's space) to open.
- Early degeneration of Claudius cells was observed around postnatal day 8 (P8).
- Progressive loss of outer hair cells began around P13, followed by massive cell death in the middle and basal turns, and secondary degeneration of spiral ganglion neurons.
Conclusions:
- Cx26 is essential for the postnatal maturation and maintenance of the organ of Corti.
- Cx26 deficiency disrupts cochlear development and homeostasis, leading to progressive hearing loss before the onset of auditory function.
