April 2009
Volume 50, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2009
Smad3 Regulate Rho Signal Pathway via Net1 in TGF-β Induced Human RPE
Author Affiliations & Notes
  • J. Lee
    Ophthalmology & Visual Science, Catholic University of Korea, Seoul, Republic of Korea
  • Y.-A. Lee
    Ophthalmology & Visual Science, Catholic University of Korea, Seoul, Republic of Korea
  • C.-K. Joo
    Ophthalmology & Visual Science, Catholic University of Korea, Seoul, Republic of Korea
  • Footnotes
    Commercial Relationships  J. Lee, None; Y.-A. Lee, None; C.-K. Joo, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 3421. doi:https://doi.org/
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      J. Lee, Y.-A. Lee, C.-K. Joo; Smad3 Regulate Rho Signal Pathway via Net1 in TGF-β Induced Human RPE. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3421. doi: https://doi.org/.

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

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Abstract

Purpose: : In previous studies we have demonstrated that RhoA dependent signaling regulate TGF-β1 induced cytoskeleton reorganization in human retinal pigment epithelium cell line, ARPE-19 cells. In addition to RhoA signaling, Smad pathways have also been shown to mediate actin of TGF-β1. The purpose of this study were to examine what regulate Rho GTPase activity and to test whether Smad signaling cross-talks with Rho pathways during actin rearrangement induced by TGF-β1.

Methods: : Serum-starved ARPE-19 cells were incubated with vehicle alone or 10ng/ml TGF-β1 and their morphological changes were examined by phase-contrast microscopy. Using siRNA targeting for NET1 and dominant negative Smad3 and active Smad3 DNA construct, we show that these proteins are critical to TGF-β1 induced cytoskeleton reorganization and RhoA activation. Actin reorganization was examined by immunochemistry and confocal microscopy. Protein expression was analyzed by Western blot analysis.

Results: : Using siRNA targeting for NET1, we show that NET1, the GEF of RhoA, is critical to TGF-β1 induced cytoskeleton reorganization and RhoA activation. In ARPE-19 cells that lack NET1, TGF-β1 induced stress fiber was not observed. Interestingly, dominant negative smad3 expressing cells, TGF-β1 failed to induce stress fiber formation.

Conclusions: : We demonstrate that Smad3 regulate RhoA activation and cytoskeleton reorganization in TGF-β1 induced ARPE-19 cells. These data define a new role for Smad as a modulator of RhoA activation while regulating TGF-β1 induced epithelial-mesenchymal transitions.

Keywords: EMT (epithelial mesenchymal transition) • retinal pigment epithelium • cytoskeleton 
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