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. Author manuscript; available in PMC: 2013 Sep 14.
Published in final edited form as: Exp Biol Med (Maywood). 2010 Apr;235(4):434–446. doi: 10.1258/ebm.2009.009281

Figure 2.

Figure 2

Hypothesized scheme for how Notch signaling maintains hair cell and supporting cell fates. Hair cells express the hair cell-specific transcription factor Atoh1 and the Notch ligands Delta1 and Jagged2. These signal to neighboring supporting cells through Notch receptors. Cleavage of the Notch receptor releases an intracellular domain (ICD) that travels to the nucleus and co-operates with RBPJk to activate transcription of Notch target genes such as members of the Hes and Hey gene families. These Hes family genes repress expression of hair cell-specific genes such as Atoh1 and maintain the supporting cell state. When Notch signaling is blocked in supporting cells (bottom left), Atoh1 and other hair cell genes are no longer repressed, and supporting cells trans-differentiate into hair cells. In models of Atoh1-based gene therapy (bottom right), the ectopic expression of Atoh1 is hypothesized to drive supporting cells to a hair cell fate.