MicroRNA-200 family members are weakly expressed in the neurosensory epithelia of the developing zebrafish (Danio rerio) inner ear.

MicroRNA-200 family members are expressed in the developing mouse inner ear and in zebrafish (Danio rerio) olfactory epithelia, taste buds, and neuromasts, and have also been shown to be associated with differentiation of olfactory and taste buds. However, the role of the miR-200 family in the inner ear of zebrafish had not been studied. We investigated the expression and function of the miR-200 family in the zebrafish inner ear via in situ hybridization and loss-of-function methods. Expression of the miR-200 family was weak and dispersed throughout the developing zebrafish inner ear. After knockdown of miR-200 family members in the developing inner ear, no significant differences in development were observed compared to the controls. Otic vesicles, otoliths, and semicircular canals appeared normal. Compared with less differentiated olfactory filaments in olfactory epithelia, the development of hair cells and statoacoustic ganglion neurons were normal. The kinocilia and stereocilia of hair cells, the innervation of hair cells, and the formation of ribbon synapses were also unaffected. Overall, we conclude that the miR-200 family has a negligible role in the development of zebrafish inner ear; the functions of the miR- 200 family may be organ-specific.