June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Rho is involved in regulation of myocardin-related transcription factor and myofibroblast transdifferentiation of RPE cells
Author Affiliations & Notes
  • Shigeo Tamiya
    Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Louisville, Kentucky, United States
  • Ganapathy Jagatheesan
    Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Louisville, Kentucky, United States
  • Shunichiro Ueda
    Tokyo Ika Daigaku Byoin, Shinjuku-ku, Tokyo, Japan
    Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Louisville, Kentucky, United States
  • Footnotes
    Commercial Relationships   Shigeo Tamiya, None; Ganapathy Jagatheesan, None; Shunichiro Ueda, None
  • Footnotes
    Support  NIH Grant EY030060
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 3636. doi:
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      Shigeo Tamiya, Ganapathy Jagatheesan, Shunichiro Ueda; Rho is involved in regulation of myocardin-related transcription factor and myofibroblast transdifferentiation of RPE cells. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3636.

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

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Abstract

Purpose : Myocardin-related transcription factor (MRTF) has been implicated as a key signaling molecule involved in transdifferentiation of retinal pigment epithelial (RPE) cells into myofibroblasts, which play a critical role in development of fibrosis. The purpose of this study was to examine the role of Rho signaling in MRTF function and myofibroblast transdifferentiation of RPE cells.

Methods : Transforming growth factor-beta2 (TGF-b2) was used to stimulate primary cultured porcine RPE cells. Confocal microscopy was utilized to examine immunocytochemically stained MRTF-A. Myofibroblast markers, alpha-smooth muscle actin (aSMA) and tropomyosin-1 (TPM1), was examined by western blot analyses. Myofibroblast function was assessed by collagen hydrogel contraction. The following inhibitors were used: CCG-1423, cell permeable C3 transferase, and Y27632 for inhibition of MRTF signaling, Rho and ROCK, respectively.

Results : TGF-b2 stimulation induced MRTF-A nuclear localization and myofibroblast differentiation, characterized by significantly increased myofibroblast marker expression as well as enhanced hydrogel contraction. CCG-1423 prevented induction of these myofibroblastic traits by TGF-b2, confirming the critical role of MRTF in myofibroblast transdifferentiation. Rho inhibitor suppressed MRTF-A nuclear localization, and significantly reduced myofibroblast marker expression as well as hydrogel contraction. In contrast, ROCK inhibition had little effect on TGF-b2 induced MRTF localization or myofibroblast differentiation, and significantly reduced hydrogel contraction only at a higher concentration.

Conclusions : Our data show Rho, but not its downstream effector ROCK, is involved in the regulation of MRTF localization and function. Further understanding of mechanisms involved in Rho activation as well as signaling linking Rho to MRTF nuclear localization may reveal novel targets for therapeutic intervention for fibrotic complications in which RPE cells play a significant role such as proliferative vitreoretinopathy or exudative age-related macular degeneration.

This is a 2021 ARVO Annual Meeting abstract.

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