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A.C. Paull, M.M. Wright, D.R. Whikehart; The p53 Protein Family in Central vs. Peripheral Human Corneal Endothelium . Invest. Ophthalmol. Vis. Sci. 2003;44(13):923.
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Purpose: The cell cycle control protein, p53, is functionless in half of all cancers and is known to negatively regulate cell division. Since human corneal endothelial cells may contain dividing stem cells at the peripheral limbus (Whikehart DR et al, ARVO Abstract #1627, 2002), we investigated whether p53 levels are higher in the peripheral vs. the central endothelial tissue of human corneal cells. Two novel p53 family member proteins, p63 and p73, were also investigated. Although p63 and p73 are highly homologous to p53, previous data attributes both tumor-supressing and tumor-stimulating characteristics to these proteins (Yang A and McKeon F, 2000). In this study, we analyzed the expression of p53, p63, and p73 in the central vs. the peripheral cells of human corneal endothelium. Methods: An 8mm diameter section of human cornea was dissected, separating a central zone from the peripheral cornea/limbus. The endothelial cell layer was dissected from these two zones and analyzed for p53, p63, and p73 using Western Blot immunodetection and the ELISA assay. Results: p53 protein levels were high in the central area of the human corneal endothelial tissue but very low in the peripheral area of the same tissue. Additionally, p63 and p73 followed the same expression pattern as p53, in which expression was strong in the central area, but not in the peripheral area of the human corneal endothelium. Conclusions: Since p53 is a negative regulator of cell division, the absence of p53 from the peripheral cells of corneal endothelium further suggests that the peripheral cornea/limbus may contain stem cells involved in regeneration. Furthermore, the stronger expression of p63 and p73 in the central tissue compared to peripheral tissue supports previous findings that p63 and p73 may have a similar role to p53 in negatively regulating cell division in the central tissue. Commercial Relationship: None
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