Cellular activities during the development and regeneration of hair cells
Each sensory hair cell of the auditory, vestibular, or lateral-line system bears a mechanically sensitive hair bundle on its apical surface. Because this structure is sensitive to stimulation along a specific axis, it is important that every hair cell be precisely aligned such that it can respond effectively to vectorial stimuli. We have investigated a series of morphogenetic events—Notch-delta signaling, cellular rearrangements, and hair-bundle rotations—that determine the polarities and orientations of newly formed hair cells in the in the zebrafish larva. Some of the same signals may be involved in specifying the highly specific neural connections of the hair cells. Moreover, in non-mammalian vertebrates similar processes underlie the regeneration of hair cells. However, mammals including humans have lost that capacity, so damage to cochlear hair cells results in progressive hearing loss. We have identified the Yap signaling pathway as key to the proliferation of the supporting cells from which hair cells originate, and have found a chemical compound that restores the proliferative capacity of adult mammalian ears.
Rockefeller University, New York, USA