Dizzy and Deaf

Investigation of the role cadherin 23 and protocadherin play in the tip links of auditory and vestibular hair cells. This is image is from an adult mouse utricle in which the cadherin 23 gene has been knocked out. Tip links connect the tips of stereocilia to each other and when intact, pull traction on the stereocilia membrane resulting in peaked stereocilia tips. Because cadherin 23 is an essential component of the tip link in stereocilia, the absence of this protein in this knockout results in absence of tip links, which manifests as flattened, blunted stereocilia tips. Mice with this defect exhibit both vestibular and auditory deficits (dizzy and deaf). Mutation of the cadherin 23 gene has been linked to type 1D Usher syndrome in humans. Image was captured using a scanning electron microscope at 5.0kV.