Myosin XVA: dancing at the tips of the stereocilia

Myosins comprise a large superfamily of adenosine triphosphatases (ATPases) that interact with actin filaments to generate motility or force. Unconventional myosins are implicated in diverse cellular processes including organelle trafficking, F-actin organization and cell movement. The unconventional myosin, myosin XVA (MYO15A), is localized at the tips of stereocilia in the inner ear hair cells and plays important roles in the development and maintenance of stereocilia. Mutations in MYO15A / Myo15a genes are responsible for hearing loss DFNB3 and shaker-2 in human and mice, respectively. In the present review, we will discuss the expression and alternative splicing of the MYO15A gene, the biochemical properties of the MYO15A protein and the association of MYO15A mutations with hearing loss. We will also discuss the recent investigations into the mechanism of how MYO15A regulates stereocilia development and maintenance. At present we are just beginning to appreciate the important roles of MYO15A in stereocilia, and further investigations are warranted to fully understand them.