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Z.L. Chen, D. Liang, Q. Chen, T. Yang, P.A. Overbeek; Specificity of Cell Cycle Regulation in Lens Epithelial Cells by Overexpression of SV40 T Antigen in Transgenic Mice . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1247.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Previous studies have shown that the retinoblastoma protein (pRb) is essential for cell cycle exit during lens fiber cell differentiation. However, little is known about which Rb family members are critical for cell cycle control in lens epithelial cells. Here we describe experiments using wild type SV40 T antigen and Trunc T antigen to study cell cycle regulation in the lens epithelial cells in transgenic mice. Methods: Wild type SV40 T antigen and Trunc T antigen (encoding the first 190 amino acids) were linked to the lens specific promoters DREAM and FoxE3. Transgenic mice were produced by microinjection and characterized by histology, immunohistochemistry (IHC) and in situ hybridization (ISH). Cell death was assayed using the TdT-dUTP teminal nick-end labeling (TUNEL) procedure. Results: At E12.5, strong expression of the SV40 Tag transgenes was detected in lens epithelium and fiber cells in DREAM-Tag mice, but only in lens epithelial cells in FoxE3-Trunc T mice. Wild type T antigen induced increased numbers of BrdU positive lens epithelial cells, and expression of Trunc T resulted in BrdU positive fiber cells. Apoptosis was seen in both wild type T and TruncT transgenic lenses. In lens epithelial and fiber cells of DREAM-Tag mice, ISH and IHC showed upregulation of expression of cyclins (A2, B1 and E), E2Fs (2 and 5) and Sox2; expression of E-cadherin, α and ß-crystallins was inhibited. Conclusion: The DREAM promoter is active in lens epithelium and fiber cells, while FoxE3 promoter is active in lens epithelium. Wild type T antigen can (i) induce lens epithelial cells to proliferate and (ii) can change E-cadherin expression in lens epithelium. Trunc T causes less lens hyperproliferation. Thus, cell cycle regulation in the lens epithelium may be controlled by multiple factors in addition to the pRb family.
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