Coupling the cell cycle to development and regeneration of the inner ear

• Sensory epithelial cells are characterized by ordered cell cycle exit and postmitotic state.
• Cell cycle deregulation triggers aberrant proliferation of hair cells or supporting cells.
• Various signalling pathways feed to cell cycle activity in the sensory epithelia.
• Proliferative capacity of hair cells and supporting cells is temporally and spatially restricted.
• Cell cycle reactivation of hair cells leads to cell death.
• Supporting cell's proliferative potential could possibly be therapeutically relevant.

Cell cycle exit and acquirement of a postmitotic state is essential for the proper development of organs. In the present review, we examine the role of the cell cycle control in the sensory epithelia of the mammalian inner ear. We describe the roles of the core cell cycle regulators in the proliferation of prosensory cells and in the initiation and maintenance of terminal mitosis of the sensory epithelia. We also discuss how other intracellular signalling may influence the cell cycle. Finally, we address the question of whether manipulations of the cell cycle may have the potential to create replacement cells for the damaged inner sensory epithelia.