Hair cells in the inner ear, responsible for hearing and balance, are prone to damage. Extreme noise, infections, trauma, and aging are just few of the many things that cause the destruction of these delicate sensors. Once lost, hair cells do not grow back in humans and that leads to the loss of both hearing and proper balance.
However, a recent study of a team of researchers from Rockefeller University has provided a new way on how to regenerate these hair cells in the inner ear. They have identified two genes that are both responsible for the production of these sensory receptors in young mice.
The team led by Ksenia Gnedeva, a postdoc in A. James Hudspeth's Laboratory of Sensory Neuroscience, investigated the development of a murine vestibular organ - utricle - and assessed the changes of the gene expression involved, as described. Utricle is a hair cell-lined organ inside the inner ear that is responsible for detecting sound and motion.
The team found out that the activities of two genes - Sox4 and Sox11 - were down-regulated shortly after the mice were born, in which case, the hair cells ceased to develop inside the organ. The team believed that such genes produced the necessary transcription factors or proteins that play vital roles in regulating the expression of other genes involved in hair cell growth.
To test such claim, Gnedeva tried to alter the expression of Sox4 and Sox11. When both genes were shut down, they found that the mice developed abnormal inner ears. In contrast, when the gene was turned on, it resulted to the production of new hair cells inside the inner ears of mice.
"Our ultimate goal is to find a target that would allow us to restore hair cells later on in life. It appears possible that these proteins, or perhaps other steps in the same pathway, might be potential targets," says Gnedeva in a press release, as she also plans to explore other molecular mechanisms that may be useful in activating these two valuable genes.
The study appears in the Proceedings of the National Academy of Sciences.