Abstract
The molecular mechanisms coordinating cell cycle exit with cell differentiation and organogenesis are crucial, yet poorly understood, in the aspect of normal development of inner ear. The cell cycle is strictly regulated during development of inner ear to produce the correct number of sensory hair cells, supporting cells and neurons, which are required for hearing and balance function. It has been reported that the tumor suppressor phosphatase PTEN is essential for normal embryonic development, and PTEN expression is associated with cell cycle progression as well as neuronal differentiation. The aim of this study is to investigate the possible role of PTEN signaling during development of inner ear in mice. The results showed that PTEN began to express in the progenitor cells of cochleovestibular ganglion (CVG) neurons and progenitor cells of hair cells when the primordial organ of Corti exit from cell cycle by onset of p27kip1 expression. During the processes of hair cell differentiation, PTEN is expressed in the hair cells according to a spatial-temporal gradient. Inversely, p27kip1 expression is down-regulated in hair cells. After maturation of organ of Corti, PTEN becomes negative in hair cells and spiral ganglion neurons. In addition, in the PTEN+/- mice, the appearance of supernumerary hair cells was found when compared to the Wild-type mice. These findings suggested that PTEN may play a role in regulating the morphological development of inner ear [J Physiol Sci. 2007;57 Suppl:S104]
