Hair Cell Differentiation

The mammalian inner ear is a highly complex structure containing six distinct sensory organs. Each sensory organ comprises mechanosensory hair cells and nonsensory supporting cells arranged in a cellular mosaic. Hair cells and supporting cells are both derived from progenitor cells located in developing sensory patches. Hair cell differentiation is initiated through the expression of the transcription factor Atoh1. Initially, most progenitor cells within each sensory patch express Atoh1; however, subsequent cell–cell interactions lead to the downregulation of Atoh1 in cells that will develop into supporting cells. In hair cells, the expression of Atoh1 leads to the initiation of a signaling cascade that promotes hair cell development and survival.