Role of cadherins in Ca2+-mediated cell adhesion and inherited photoreceptor degeneration.

Cadherins are Ca -binding, transmembrane proteins involved in cell adhesion. Recently, three cadherin molecules, cadherin-23, protocadherin-15, and cadherin-3 were found to be defective in various human diseases, many of them with photoreceptor degeneration and/or sensorineural hearing loss as major featuresUsher syndrome type 1D (USH1D), USH1F, and hypotrichosis with juvenile macular dystrophy, respectively. The process, by which mutations lead to photoreceptor degeneration is still not fully understood. Data from the inner ear phenotype of USH1 mouse models suggest that loss of cell adhesion is a crucial event.