April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Tropomyosin Regulation of Stress Fiber Formation and EMT in Lens Epithelial Cells
Author Affiliations & Notes
  • Eri Kubo
    Dept of Ophthalmology, Kanazawa Medical University, Kahoku-gun, Japan
  • Hiromi Osada
    Dept of Ophthalmology, Kanazawa Medical University, Kahoku-gun, Japan
    Dept of Ophthalmology, Anamizu General Hospital, Ishikawa, Japan
  • Naoko Shibata
    Dept of Ophthalmology, Kanazawa Medical University, Kahoku-gun, Japan
  • Etsuko Kiyokawa
    2. Department of Oncogenic Pathology, Kanazawa Medical University, Ishikawa, Japan
  • Hiroshi Sasaki
    Dept of Ophthalmology, Kanazawa Medical University, Kahoku-gun, Japan
  • Dhirendra P Singh
    3. Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 1222. doi:
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      Eri Kubo, Hiromi Osada, Naoko Shibata, Etsuko Kiyokawa, Hiroshi Sasaki, Dhirendra P Singh; Tropomyosin Regulation of Stress Fiber Formation and EMT in Lens Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1222.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a leading cause of posterior capsule opacification (PCO) after cataract surgery. Transforming growth factor (TGF)-β2 and fibroblast growth factor (FGF)-2 are frequently and abundantly expressed in LECs and are considered key mediators of EMT by regulating the expression of extracellular matrix genes, including the tropomyosin (Tpm) family of proteins. We previously showed that the elevated expression of Tpm1α/2β was related to the progression of rat PCO and of human cataracts with anterior subcapsular fibrosis. Using mouse and human LECs, we analyzed the effects of FGF2 and/or TGFβ2 on the expression and role of Tpm1α/2β and α-smooth muscle actin (αSMA) in stress fiber formation, as well as assessing EMT related gene expression.

Methods: Primary cultured mouse and human LECs showing reduced expression of Tpm1α/2β were treated with 0 to 10 ng/ml of FGF-2 and/or TGFβ-2. Tpm1α and 2β were selectively knocked down by transfecting their corresponding siRNAs using lipofectin. Mouse and human Tpm1α/2β were overexpressed by transfecting GFP-Tpm1α and/or GFP-Tpm2β. The expression of proteins related to EMT was assayed by western blotting using specific antibodies. F-actin distribution in LECs was visualized using fluorescent phalloidin.

Results: Stress fiber formation was induced by the addition of TGFβ2 and inhibited by the addition of FGF2. Silencing of Tpm1α and/or -2β expression significantly inhibited TGF-β2-mediated stress fiber formation and αSMA expression. In contrast, overexpression of Tpm-1α and/or -2β induced stress fiber formation and αSMA expression. LECs overexpressing Tpm1α and or 2β displayed overmodulation of genes related to EMT.

Conclusions: Tpm expression mediates the regulation and reprogramming of the actin cytoskeleton during the process of EMT and fiber regeneration in PCO, and may lead to innovative avenues of investigation and treatment of PCO.

Keywords: 445 cataract • 512 EMT (epithelial mesenchymal transition) • 652 posterior capsular opacification (PCO)  
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