Genetic insights into the morphogenesis of inner ear hair cells

The mammalian inner ear is a sensory organ that has specialized hair cells that detect sound, as well as orientation and movement of the head. The 'hair' bundle on the apical surface of these cells is a mechanosensitive organelle that consists of precisely organized actin-filled projections known as stereocilia. Alterations in hair-bundle morphogenesis can result in hearing loss, balance defects or both. Positional cloning of genes that underlie hereditary hearing loss, coupled with the characterization of corresponding mouse models, is revealing how hair cells have adapted the molecular mechanisms of intracellular motility and intercellular adhesion for the morphogenesis of their apical surfaces.