Abstract
Purpose:
FGF2 and TGFβ2 families are known to play an important role in regulating posterior capsule opacity (PCO) after cataract surgery. Using an in vivo rodent PCO model, we earlier demonstrated that the expression of tropomyosin (Tpm)1α/2β was aberrantly upregulated in remodeling the actin cytoskeleton during (epithelial-mesenchymal transition) EMT of lens epithelialcells (LECs). In the present study, we explored the effect of FGF2 and TGFβ2 on Tpm1α/2β and α-smooth muscle actin (αSMA) using mouse LECs from Peroxiredoxin 6-deficient (Prdx6-/-) and wild-type (Prdx6+/+) mice coupled with a rat PCO model system.
Methods:
Prdx6-/- LECs overexpressing Tpm1α/2β, and Prdx6+/+ LECs with low expression of Tpm1α/2β were used. LECs growing in DMEM containing 0.5% bovine serum albumin were treated with 0 to 10ng/ml of FGF-2 and TGFβ-2. MTS and TUNEL assays were used to detect cell viability and apoptotic cell death. Expression of several genes related to lens EMT were examined using real-time PCR and Western analysis using their corresponding specific probes. All animal experiments were conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Extracapsular lens extractions (ECLEs) were performed in Sprague Dawley rats to generate the rat PCO model.
Results:
After treatment with TGFβ2, expression of Tpm1α/2β and αSMA were upregulated in Prdx6+/+ LECs, and cell viability was decreased. In contrast, with treatment with FGF-2 in the presence or absence of TGFβ2, expression of Tpm1α/2β and αSMA were markedly decreased in Prdx6-/- LECs and cell viability was increased. FGF2 treatment of also blunted the formation of stress fiber in LECs that overexpressed Tpm1α/2β. FGFR2 was localized in regenerated lens fiber in rat PCO model as evidenced by immunohistochemical analyses.
Conclusions:
FGF-2 inhibits the TGF-β2-mediated induction of Tpm1α/2β and αSMA. The findings may help to clarify the condition of reprogramming of the actin cytoskeleton during morphogenetic EMT cell proliferation and fiber regeneration in PCO. Consideration of the balance of FGF-2 and EMT regulation may provide a clue to a method of postponing PCO.
Keywords: 652 posterior capsular opacification (PCO) •
512 EMT (epithelial mesenchymal transition) •
445 cataract