p53 Is Necessary for bFGF-Induced Lens Differentiation

Abstract

Purpose: : The tumor suppressor, p53 plays an important role in the ocular lens. Knockout of the p53 gene or inactivation of the p53 gene through overexpression of a viral gene, E6, leads to cataractogenesis. However, the molecular mechanisms and signaling pathways by which p53 regulates lens differentiation and pathology remains unknown. To explore how p53 may regulate lens differentiation and pathogenesis, we have examined the role of p53 in bFGF-induced differentiation of lens epithelial cell in vitro, and the expression pattens of the p53 downstream genes in mose eye during mouse development.

Methods: : RT-PCR was used to detect mRNA change, Western blot was used to analyze protein expression levels and immunofluorescence was used analyze the developmental expression and activities of the p53 and its downstream genes.

Results: : p53 is highly expression in both lens epithelial and fiber cells of the embryonic developing lens. In addition, phosphorylation of p53 at Ser-15 and Ser-20 are also developmentally regulated. Overlapping with the expression and phosphorylation patterns of p53, the p53 downstream genes, p21, bak, bax, and mdm2, were also expressed similarly. In the bFGF-induced lens fiber differentiation model of the cultured mouse lens epithelial cells, the phosphorylation of p53 and its downstream genes are both up-regulated under bFGF treatment. The bFGF-induced lentoid formation and expression of the differentiation marker β-crystallin are dependent on the presence of p53.

Conclusions: : p53 actively regulates lens differentiation in vivo and in vitro. P53 regulates lens differentiation through its down-stream target genes.

Keywords: development • cataract • growth factors/growth factor receptors