Genetic Control of Inner Ear Development in Xenopus Laevis

Inner ear functions (such as hearing and balance) rely on a highly-ordered arrangement of mechanosensory hair cells. To reconstitute hair cells using defined treatments, more needs to be known about what controls their development. Pax2 and Pax8 are transcription factors known to regulate vertebrate organogenesis, including that of the inner ear. Depletion of Pax2and Pax8(separately or in combination) has been researched in mice and zebrafish. The results show a range of vestibular and cochlear defects. To understand more, we have characterized depletion of Pax2/Pax8genes in frogs (Xenopus laevis), which have been microinjected with antisense morpholino oligos (MOs) against Pax2and Pax8at the 8-cell stage. We have found that depletion of these gene products, in combination, can block formation of an otic vesicle and surrounding sensory neural pathways unilaterally in frogs. Our results suggest that expression of Pax2/Pax8genes are essential for proper ear morphogenesis. Furthermore, we found that this depletion results in a reduction of Sox9expression from the early embryo. With this information, a combination of transcription factors necessary for hair cell development is closer to being determined.