Mutated microRNA causes deafness

A mutated form of microRNA is responsible for deafness in mice because it prevents the development of sensory cells vital to hearing, a finding which may have important implications for human hearing loss

It takes twelve days post-birth before a mouse fully develops the ability to hear, during which time their immature hair cells follow precise genetic instruction that regulate development of distinct types of sensory hair cells – the inner and outer hair cells.

Researchers from the University of Sheffield found that in a strain of mice called diminuendo – which carry a single base mutation in the miR-96 gene – hair cell development is arrested around birth. miR-96 normally regulates hair cell development by influencing the expression of different genes associated with developmental processes.

Researchers – led by Dr Walter Marcotti – discovered the mutation not only hinders the development of the mechanically sensitive hair bundle on the cell apex, but also the synaptic structures at the base that govern transfer of electrical information to the sensory nerve.

“Our research has provided new and exciting results that further understanding of auditory development as well as possible molecular targets for the development of future therapies,” said Marcotti, Royal Society university research fellow from the department of biomedical science.

The mutation in miR-96 is known to cause deafness in humans and microRNA molecules can be targeted by drugs.

“Progressive hearing loss affects a large proportion of the human population, including new born and young children,” Marcotti said. “Despite the relevance of this problem, very little is currently known regarding the genetic basis of progressive hearing loss.”