CELLULAR-DISTRIBUTION OF MYOSIN-V IN THE GUINEA-PIG COCHLEA

The importance of unconventional myosins to hearing has recently been revealed by the identification of myosins-VI and -VII as the defective genes in mouse mutations and in a human syndrome which lead to profou nd hearing loss. Another class of novel myosins (V) has been implicate d in the trafficking of intracellular vesicles in neurons and other se cretory cells. We used affinity-purified antibodies to determine the l ocalization of myosin-V in the guinea pig inner ear. In the sensory ep ithelium of the cochlea, myosin-V epitopes were recognized in neuronal and supporting cells. Neuronal labelling was most intense in the affe rent innervation of inner and outer hair cells. Supporting cells label led were cells of Hensen and Deiters, and inner border, inner phalange al, inner sulcus and interdental cells. In the vascular tissue of the cochlea, we observed staining of intermediate cells of the stria vascu laris and of border cells between the stria and the spiral prominence. Staining of afferent chalice nerve endings was observed on type I ves tibular hair cells. The results suggest that, like myosins VI and VIII , myosin-V is localized in positions that may be critical to auditory function.