Hox gene and development of the auditory circuit

Sound vibration is sensed by hair cells in the inner ear. The information is transmitted to the cochlear nucleus in the brainstem via spiral ganglion neurons. The information is further transmitted to higher relaying centers in the brain such as superior olivary complex and inferior colliculus. The connectivity between these components is topographically organized in a frequency-specific manner. It is known that the organization is well-established from the beginning of the circuit development. However, little is still known about the molecular mechanisms underlying the development of connectivity in the auditory circuit. Homeobox transcription factors of the Hox gene family are known for their involvement in early anterior-posterior axis patterning of neuronal progenitors in the hindbrain. Recent evidence indicates that they also play important roles in late aspects of neuronal development and establishment of topographic circuitry. Moreover, a mutation in the HOXA2 gene has been recently shown to be responsible for hearing deficits in humans. By means of spatiotemporally controlled Hoxa2 and Hoxb2 conditional mutations in the mouse we analyzed the involvement of these factors in auditory circuit development and connectivity.

特別講演要旨 (Summary of Special Lecture)