BASEL, SWITZERLAND — Although current approaches to hearing loss management primarily involve hearing aids or, in some instances, cochlear implants, researchers at the University of Basel are advancing our understanding of hearing loss mechanisms.
“In order to develop new therapies, we need to better understand what the auditory sensory cells need for proper function”
–Dr. Maurizio Cortada, Dept. of Biomedicine at University of Basel
Partnering with Professor Michael N. Hall’s research team at the Biozentrum, Dr. Maurizio Cortada delved into the signaling pathways affecting sensory hair cells located within the inner ear. Their investigation revealed a central regulator, as detailed in their report in the journal iScience.
This critical signaling pathway, referred to by researchers as the mTORC2-signaling pathway, plays a crucial role in various cellular functions, including cell growth and cytoskeleton maintenance. However, its significance for the hair cells in the inner ear had not been previously studied.
Importance of the mTORC2 Signaling Pathway
When the researchers removed a central gene of this signaling pathway in the hair cells of the inner ear of mice, the animals gradually lost their hearing. By the age of twelve weeks, they were completely deaf.
Further examination revealed that the sensory hair cells in the inner ear lost their sensors without the mTORC2 signaling pathway. These hair cells, essential for translating sound into nerve signals, exhibited shortened protuberances akin to tiny hairs under electron microscopes. Additionally, the number of synapses responsible for transmitting signals to the auditory nerve significantly decreased.
Dr. Cortada suggests that previous studies have indicated a decrease in the production of vital proteins within this signaling pathway with age. This decline may be linked to the loss of synapses and diminished functionality of auditory sensory cells within the inner ear, ultimately contributing to age-related hearing loss.
Confirmation of this hypothesis could open doors to future therapies. Given the accessibility of the middle and inner ear, localized treatments like medications or gene therapies could become viable options.
Reference:
- Maurizio Cortada, Soledad Levano, Michael N. Hall, Daniel Bodmer. mTORC2 regulates auditory hair cell structure and function. iScience (2023), doi: 10.1016/j.isci.2023.107687
Source: Univ. Basel; iScience
