Purchase this article with an account.
M. Deng, L. Xiao, L. Gong, D. Yuan, J. Liu, H. Chen, Q. Yan, D. W. Li; The P53 Target Gene, Bak, Is Involved in Mouse Lens Differentiation. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2629.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The mitochondrial cell death pathway plays a critical role in mammalian lens differentiation. Our previous studies showed that the tumor suppressor, p53, regulates bFGF-induced lens fiber cell differentiation through control of the Bcl-2 family member, Bak. However, how Bak mediates regulation of lens differentiation remains unknown.
The basic FGF-induced lens fiber differentiation model was established using cultured mouse lens epithelial cell line, αTN4-1. Stable clones of p53 and bak knockdown were generated through respective overexpression of the p53 and bak shRNA plasmids. The bFGF induction of lens differentiation in the normal or attenuated expression of either p53 or Bak was analyzed by cell fraction, confocal microscopy and co-immunoprecipitation.
Phosphorylation of p53 at Ser-15 and Ser-20 was enhanced, and Bak expression was also up-regulated during bFGF-induced lens differentiation. Moreover, the mouse lens epithelial cells were induced to form the lentoids and express the differentiation marker, β-crystallin. However, in p53-knockdown lens epithelial cells, phosphorylation of p53 and expression of Bak were significantly attenuated. Associated with this attenuation, the mouse lens epithelial cells remained undifferentiated. In Bak-knockdown lens epithelial cells, similar phenotype was also observed. Furthermore, during bFGF induction, phosphorylated p53 at Ser-20 was increased in nucleus but phosphorylated p53 at Ser-15 was accumulated in cytoplasm. The cytoplasmic p53 was found interacting with Bak. In addition, beside the strong expression of Bak in cytosol, it was also found in nuclear fraction and the nuclear faction was increased during bFGF induction.
Our results suggest that Bak, the pro-apoptotic member of the Bcl-2 family mediates p53-dependent bFGF-induced lens differentiation.
This PDF is available to Subscribers Only