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E. Kubo, N. Hasanova, Y. Takamura, D. P. Singh, Y. Akagi; Tropomyosin Mediates Transdifferentiation of Lens Epithelial Cells in Rodent Posterior Capsule Opacifications and Human Cataract. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3730. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Transdifferentiation of lens epithelial cells (LECs) into myofibroblastic/fibroblastic cells occurs during posterior capsule pacifications (PCO) after cataract surgery and anterior subcapsular cataract (ASC). Tropomyosins (Tpm) are actin cytoskeleton regulatory proteins that modulate the stability and localization properties of actin filaments. The present study quantified the Tpm expressions in rodent PCO and human cataractous LECs to determine the role of the Tpm in the reorganization of the actin cytoskeleton during transdifferentiation of LECs.
Extracapsular lens extractions (ECLEs) were performed in 18 consecutive Sprague Dawley rats. Animals were sacrificed at 0, 7 and 14 days after surgery. Eyes were enucleated and processed for protein blot or immunohistochemistry using anti-Tpm1α/2β, α-smooth muscle actin (αSMA) and βactin antibodies. We prospectively studied a consecutive series of 90 eyes at Fukui University Hospital in Japan. Patient age and severity of age-related cataract as classified according to the modification of the Lens Opacities Classification System version III (LOCSIII) were recorded. At cataract surgery, LECs with anterior capsules obtained by continuous curvilinear capsulorrhexis (CCC) were corrected and mRNA levels of Tpm2β were measured using the real time PCR method.
Immediately after ECLE, rat LECs were present only under the anterior capsule and at the lens bow, and Tpm1α/2β and αSMA proteins were not detected. Seven and 14 days after ECLE, PCOs were formed and Tpm1α/2β and αSMA proteins were highly expressed in rat LECs. In human LECs, Tpm2β mRNA was detected, with significant higher expressions in LECs obtained from nuclear cataract and ASC patients.
Highly expressed Tpm in PCO and ASC may help to reorganize the actin cytoskeleton during morphogenetic transdifferentiation. The study may help to elucidate underlying molecular mechanisms involved in the etiology and progression of catractogenesis.
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