More on Aged-Related Hearing Loss

A team of researchers from the University of Minnesota Medical School have learned more about the way that different types of age-related hearing loss occur in humans.

The experiment was carried out, as usual, in mice, by James Ervasti, PhD, and colleague Ben Perrin, PhD.

They examined how two very closely related genes contributed to hearing function in mice, and understanding this was rather important as mutations in the two genes are linked to deafness in humans.

As a result, they discovered two key cellular processes that are necessary to maintain auditory function.

The two genes encode proteins called β-actin and γ-actin, which are both related to deafness-causing mutations in humans.

They include the main structural components of stereocilia (hair-like fibers in the ear), that transform mechanical sound energy into nerve signals that allow humans to hear.

There is only 1% difference between the two proteins, which has however been conserved through evolution from birds to mammals.

This phenomenon implies that each one has a special function different from the other, so Ervasti and Perrin knocked out each gene in mouse auditory hair cells, to see their specific roles.

They discovered that β-actin and γ-actin proteins had different maintenance functions that together allowed mice to hear, by keeping the hair-like fibers healthy.

Mice with the genes knocked out had normal hearing at young ages and developed certain types of hearing loss and stereocilia pathology depending on the lost protein.

Perrin explained that “these separate maintenance pathways are likely important for maintaining auditory function during aging and may contribute to future understanding of common forms of age-related hearing loss in humans.”

This new study could eventually help physicians develop drugs to fight progressive hearing loss, as this is a problem that affects most people later in life.

The paper is published in the open-access journal PLoS Genetics.