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G. Duncan, S. Tamiya, I.M. Wormstone; Antagonistic effects of TGFbeta and EGF on gene expression in the human lens capsular bag . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2332.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Posterior capsule opacification (PCO) develops from a combination of lens cell growth, differentiation and trans–differentiation of lens epithelial cells following cataract surgery. Two major growth factors believed to be involved in the process are transforming growth factor beta 2 (TGFß2) and epidermal growth factor (EGF). We therefore utilised an in vitro human lens capsular bag model to investigate the roles of these growth factors in PCO.Methods:Sham cataract operations were carried out on donor eyes and the resulting lens capsular bags were removed, pinned to a plastic culture dish and cultured in serum–free EMEM either in the absence or presence of either 10ng/ml TGFß2 or 10ng/ml EGF for 28 days. Freshly isolated lens tissues served as a baseline for gene expression. Lens tissues were snap–frozen and mRNA extracted. Following reverse transcription, cDNA was amplified for the following genes: GAPDH, αA and ßB2 crystallins, and α smooth muscle actin (αSMA). PCR products were isolated by agarose gel electrophoresis and quantified using image analysis software. Results: Freshly isolated central epithelial cells contained message for αA crystallin but negligible amounts for ßB2 crystallin, or αSMA. Capsular bags removed from donors that had undergone previous cataract surgery showed expression of all genes studied including αSMA.Freshly–formed capsular bags and fibre preparations (both from clear donor lenses) contained some message for all of the genes studied except αSMA. After 28 days culture, TGFß2 induced a marked reduction in ßB2 crystallin expression, while exhibiting a stimulus in αSMA level. αA crystallin was relatively unaffected at this time point. On the other hand, EGF induced a marked increase in αA and ßB2 crystallin expression, while reducing αSMA levels. Conclusions: Exposure to TGFß2 increased expression of the transdifferentiation marker gene αSMA and this was accompanied by reduced expression of the normal lens early differentiation gene ßB2 crystallin. In contrast, EGF decreased expression of αSMA, but enhanced expression of ßB2 crystallin as well as αA crystallin. These data help explain why proteins of both normal differentiation and stimulated transdifferentiation contribute to the light scattering elements forming PCO and give an insight into the mechanisms driving normal differentiation in the human lens.
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