Curing Deafness One Step Closer

Some forms of acquired deafness, more specifically those that can be prevented by people protecting their ears when they have to, could soon be cured, thanks to efforts made by researchers at the University of Leeds. Just recently, they took a step further in understanding the underlying mechanisms that in some cases lead to deafness. They have discovered that a certain protein found in the tiny hairs located in each human ear works quite differently from others in the same area, and are hoping to exploit that to people's advantage.

“We're really excited by this discovery, as it could lead to new insights into certain forms of deafness. Mutations in this protein have been linked to hearing loss, particularly of the type connected to Usher syndrome, which is a form of degenerative deaf-blindness,” UL Faculty of Biological Science researcher Dr Michelle Peckham explains. The new chemical has been dubbed myosin 7 motor protein and is only one of the over 40 similar myosins in the human body.

“What's exciting about our findings is that we have found that, unlike muscle myosins, which have two heads, myosin 7 only has one. What's more, for the first time we've found how this myosin can be switched on and switched off,” she says. The most common types of myosin can be found in large skeletal muscles, as well as in the pericardium, the muscle of the heart.

“When switched off, the tip of its tail curls round and contacts the head, and switched on this contact is broken and the myosin stretches out. This knowledge should help inform any further studies into how a mutation can create problems in hearing,” Peckham adds. She tells that further studies may be able to shed some light on the causes of a severe inherited genetic condition known as the Usher syndrome, which makes sufferers progressively lose hearing, sight and balance.

The receptors that allow us to stay upright and know when we are falling are also located in the ear, so any damage to the auditory tract also implies at least minor disturbances in a person's ability to hold their balance. This explains why, when boxers or other fighters are hit in the ear, they lose their balance and fall to the ground. They remain “grounded” until the receptors recover, which then allow them to stand up straight again.

“Our studies on how normal myosin 7 works pave the way for understanding how a defective myosin 7 protein in Usher patients results in deafness,” Peckham, the author of a new study that has been published in this week's issue of the journal Proceedings of the National Academy of Sciences Online Early Edition, concludes.