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Xiaohui Hu, Zhenfeng Wang, Zhaoxia Huang, LING Wang, Shuai Li, Zachary G Woodward, Quan Dong Nguyen, David W Li; The Tumor Suppressor p53 Regulates gA-Crystallin Gene.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5595.
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© ARVO (1962-2015); The Authors (2016-present)
The tumor suppressor, p53 regulates a large number of target genes to control cell proliferation and apoptosis. In addition, it is also implicated in the regulation of cell differentiation in muscle, the circulatory system and various carcinoma tissues. We have recently shown that p53 also controls lens differentiation. Regarding the mechanism, we reveal that p53 directly regulates several genes including the c-Maf and Prox1, two important transcription factors for lens differentiation, and also aA and bA3/A1, the lens differentiation markers. In the present study, we present evidence to show that it also regulates the gA-crystallin gene.
Electrophoretic mobility shifting assays (EMSA) was used to detect the interaction between p53 and the gA-crystallin gene promoter. Reporter gene activity assays and in vitro mutagenesis were used to determine the specific regulation of p53 on the gA-crystallin gene promoter. ChIP assays were used to determine the in vivo binding of p53 into the gA-crystallin gene promoter.
EMSA revealed that the p53 in nuclear extracts from human lens epithelial cells (HLE) directly binds to the p53 binding sites present in the gA-crystallin gene. The exogenous wild type p53 induces the dose-dependent expression of the luciferase reporter gene driven by the basic promoter containing the gA-crystallin gene p53 binding site. In contrast, the exogenous dominant negative mutant p53 causes a dose-dependent inhibition of the same promoter. ChIP assays revealed that p53 binds to the gA-crystallin gene promoter in vivo. Finally, in the p53 knockout mouse lenses, the expression level of the gA-crystallin gene was found attenuated in comparison with that in the wild type mouse lenses.
p53 regulates gA-crystallin gene expression during mouse lens development. Thus, p53 directly regulates all 3 types of crystallin genes to control lens differentiation.<br /> (Supported by Research Prevent Blindness, Zhongshan Ophthalmic Center and Chinese Scholarship Council)
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