Molecular biology of hearing loss
Sensorineural hearing loss is caused by damage to sensory hair cells in the inner ear. These hair cells can be damaged by traumatic noise, excessive exposure to ototoxic antibiotics and exposure to certain anti-cancer drugs, such as cis-platin.
Work from our laboratory and others have shown that the sensory hair cells of the cochlea are a source of neurotrophins – small protein molecules that promote survival of the primary auditory neurons that connect with these cells.
When the hair cells die, this source of neurotrophins disappears as well. A better understanding of the molecular basis of the neurotrophic support of auditory neurons may lead to new strategies to maintain their survival.
This is important because the auditory neurons are the target of the electrical stimulation provided by a cochlear implant.
Neurotrophins are secreted and captured by neurotrophin receptors expressed on the surface of primary auditory neurons.
Recently, we have shown that after an inner ear trauma one particular neurotrophin receptor, the p75 neurotrophin receptor, is strongly up-regulated in primary auditory neurons and another class of cells in the inner ear – the Schwann cells.
The reason for this increased expression is unclear and we are working towards clarifying the role of p75 neurotrophin receptor during episodes of inner ear trauma. Because the p75 neurotrophin receptor is so dramatically increased, it is a potential candidate for targeting therapeutic drugs into the inner ear.
The Garnett Passe and Rodney Williams Memorial Foundation
US National Institutes of Health (HHS-N-263-2007-00053-C)