The circling (cir/cir ) mouse is a murine model for human non‐syndromic deafness DFNB6. The causative gene is transmembrane inner ear (tmie), in which the mutation is a 40‐kilobase genomic deletion including tmie. The function of Tmie is unknown. To better understand the function of Tmie, we observed the spatiotemporal expression of tmie in the mouse cochlea using a Tmie‐specific antibody during postnatal inner ear development. Tmie was expressed in the cochlear hair cells of the mouse inner ear from embryonic days to adult. It is postulated that Tmie protein is involved in the hair cell structural formation and maturation before hearing onset (around P14), and maintenance of organ of Corti tissues after that. The cochlear hair cells of the circling mouse showed a basal‐to‐apical gradient of outer hair cell degeneration. The hair cell stereocilia bundles revealed the abnormal structure and it expanded to the apical region. In order to find the exact localization of Tmie protein inside the cell, we transfected the plasmids expressing GFP‐Tmie fusion protein into the HEI‐OC1 auditory hair cells. Tmie protein was colocalized with Calnexin (Canx), ER marker protein, but not with beta‐COP, Golgi marker protein. We next produced the Myo7a promoterdirected tmie expression transgenic mice to induce the phenotypic rescue of circling mice in a gene therapeutic way. Some circling mice with tmie transgene showed the normal behavior and hearing ability. These results indicate that tmie has a critical role in the inner ear development and hearing ability in the mice.

The spontaneous mutant circling mouse (cir/cir) shows a circling behavior and hearing loss. We produced transgenic mice overexpressing transmembrane inner ear (tmie) gene, the causative gene, for the phenotypic rescue of the circling mouse. Through the continuous breeding with circling mice, the cir/cir homozygous mice carrying the transgene (cir/cir‐gtg) were produced. The rescued cir/cir‐gtg mice were able to swim in the water with proper orientation and did not show any circling behavior like wild type mice. Western blot and immunohistochemical analysis exhibited that the transgenic tmie was expressed in the inner ear. Inner and outer hair cells were recovered in the cochlea and spiral ganglion neurons were also recovered in the rescued mice. Auditory brainstem response (ABR) test demonstrated that the cir/cir‐gtg mice are able to respond to sound. This study demonstrates that tmie transgene can recover the hearing impairment and abnormal behavior in the circling mouse.