Fig. 2

The roles of Notch and Wnt signaling in hair cell regeneration. a Upon damage, supporting cells (SCs) can give rise to the new hair cells (HCs) through non-mitotic regeneration (b) or mitotic regeneration (c). b SCs directly trans-differentiate into HCs without entering the cell cycle. Wnt signaling promotes this process, whereas Notch signaling inhibits it though Atoh1, a key transcription factor for HC cell fate commitment. c During the mitotic regeneration, SCs proliferate first and then differentiate into new HCs. Wnt signaling is able to induce SC proliferation. Notch signaling represses SC proliferation and differentiation via the inhibitions of Wnt signaling and Atoh1expression or limiting the cell cycle reentry of SCs. Usually, the mitotic markers, such as Edu or BrdU, are used to indicate the new SCs/HCs from proliferation, which can be distinguished from the non-mitotic regenerated HCs