Spatiotemporal patterns of Musashil expression during inner ear development

Musashil (Msi I) is an RNA binding protein associated with asymmetric cell divisions in neural progenitor cells.To investigate the involvement of MsiI in the inner ear development, we studied the expression of MsiI in mouse inner ears with RT-PCR and immunohistochemistry. Immunohistochemistry revealed that MsiI was expressed in all otocyst cells at embryonic day (E) 10 and 12. MsiI immunoreactivity became lost in hair cells after E14 in vestibule and after E16 in cochlea, whereas it persisted in supporting cells until adulthood. The subcellular localization of MsiI changed from "cytoplasmic predominance" to "nuclear predominance" during the first 2 weeks after birth. The present data suggested that Msi may play a role in inner ear development.