Genes belonging to the Pax-Six-Eya-Dach regulatory network have been implicated in the development of the inner ear and its ganglion. Sixl is required for mouse auditory system development. During inner ear development, Sixl expression is first detected in the ventral region of the otic pit and later is restricted to the middle and ventral otic vesicle within which, respectively, the vestibular and auditory epithelia form. Sixl is also expressed in the vestibuloacoustic ganglion. At E15.5, Six1 is expressed in all sensory epithelia of the inner ear. Six1, as a key regulator of otic vesicle patterning at early embryogenesis, controls the expression domains of downstream otic genes responsible for respective inner ear structures. In addition, the Pax-Six-Eya-Dach pathway is involved in cell proliferation and survival.
