New Study Identifies Molecular Actors Involved in Optimal Hearing

Rebecca Lewis February 19, 2013

Restoring the innervation of the cochlea – a very complex organism composed of neurones that act as the first relay station for the transmission of sound to the central nervous system, is critical to preventing hearing problems, a new study suggests.

A team of neuroscientists from the GIGA-Neurosciences Unit at the University of Liège, headed by Dr Brigitte Malgrange and Jean Defourny has identified key proteins which intervene in the refinement of cochlear innervation (or the supply of nerves in the hearing system). The proteins, particularly the EphA4 and aphrin-15 have important roles in establishing nerve connections between sensory cells and auditory neurones.

In an experiment on mice, the researchers found that the inactivity of any of these essential proteins results to major innervation flaws. This then leads to a totally disrupted hearing ability.

The team has also identified the intercellular cascades that prevent the innervation of the cochlea. In their report which was published in the journal Nature Communications, the researchers identified ephexin, cofilin, and type II myosin light chain kinase as among the proteins that lead to defective innervation.

Cochlear Innervation

The cochlea is the auditory part of the inner ear. In this very complex region lies the Corti – a group of sensory cells connected to the spiral ganglion neurones. These neurones are responsible for the transmission of sound to the central nervous system. The development of the auditory system begins by the formation of the optic vesicle which produces sensory cells and spiral ganglion neurones. For optimal hearing, the researchers said the auditory neurones must be precisely connected to the sensory cells.

New step towards understanding hearing

According to Dr Malgrange, identifying the molecular actors involved in the innervation of the cochlea, as well as those that prevent it, is an important step towards the understanding of hearing. Most importantly, their findings can be used as basis for developing new therapies for hearing problems that affect millions of people around the world.

Source of this article:

Ephrin-A5/EphA4 signalling controls specific afferent targeting to cochlear hair cells