As people grow older, the likelihood of requiring hearing aids increases. This need can be attributed, in part, to a signaling pathway responsible for regulating auditory sensory cell function, which becomes less active as we age. Scientists at the University of Basel are currently investigating this phenomenon.
Inner ear hairs responsible for hearing
Hearing loss is a widespread issue that impacts most people. It can result from factors like loud noises and aging, leading to the deterioration and loss of auditory sensory cells and their connections in the inner ear. The primary treatment options are hearing aids or, in severe cases, cochlear implants.
Dr. Maurizio Cortada, from the University of Basel’s Department of Biomedicine and University Hospital Basel, highlights the importance of understanding the requirements for proper functioning of auditory sensory cells to develop new therapies. Researchers investigated the signaling pathways affecting inner ear sensory “hair cells” and identified a central regulator, as reported in iScience journal.
The mTORC2-signaling pathway, crucial for cell growth and cytoskeleton function, has an unexplored role in inner ear hair cells. Researchers found that deleting a key gene from this pathway in mouse inner ear hair cells led to progressive hearing loss, resulting in complete deafness by twelve weeks of age.
mTORC2 signaling pathway absence leads to hearing loss
Upon closer examination, it was found that the sensory hair cells in the inner ear experienced sensor loss due to the absence of the mTORC2 signaling pathway. These hair cells, which play a crucial role in converting sound into nerve signals, had their tiny hair-like protuberances shortened, as confirmed through electron microscopy. Furthermore, there was a decrease in the number of synapses responsible for transmitting signals to the auditory nerve.
The aging process leads to a decrease in the production of important proteins in a signaling pathway, potentially causing a decline in synapses and reduced auditory sensory cell function in the inner ear, resulting in age-related hearing loss. Confirming this connection could provide a basis for future therapies, with the middle and inner ear being accessible for local medications or gene therapies, potentially leading to new treatment options.
