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6_25_05

Signals Controlling Hair Cell Development

Background: Normal hearing depends upon the precise development of the organ of Corti, a sound-detecting structure within the inner ear that includes both sensory hair cells and non-sensory supporting cells. Scientists are trying to determine the molecular process that directs the formation of these different cell types. Developing sensory hair cells express the Math1 gene and Math1 is required for them to develop; however, its specific molecular role is unknown.

Schematic diagram of a cross section through the cochlea duct.

Schematic cross section through the cochlea duct.
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Advances: Through analysis of animals with a mutation in Math1 and by overexpression of Math1 in developing ears, NIDCD intramural scientists demonstrated that Math1 causes developing hair cells to produce signals that coordinate the formation of both hair cells and supporting cells. In particular, developing hair cells send out inhibitory signals that regulate the number of other cells that can develop as hair cells. At the same time, developing hair cells produce inductive signals that recruit nearby cells to develop as supporting cells.

Implications: These results provide valuable insights into the molecular signaling pathways that lead to the overall development and organization of the organ of Corti. Understanding how molecules direct the formation of sensory hair cells may help scientists develop ways to treat problems resulting from errors in hair cell formation.

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