Suppression of Epithelial-Mesenchymal Transition in Retinal Pigment Epithelial Cells by an MRTF-A Inhibitor

Invest Ophthalmol Vis Sci. 2019 Feb 1;60(2):528-537. doi: 10.1167/iovs.18-25678.

Abstract

Purpose: Epithelial-mesenchymal transition (EMT) in retinal pigment epithelial (RPE) cells is related to the pathogenesis of subretinal fibrosis such as that associated with macular degeneration. The role of myocardin-related transcription factor A (MRTF-A) in EMT of RPE cells and subretinal fibrosis was investigated.

Methods: The migratory activity of human RPE-1 cells in culture was evaluated using a scratch assay. The subcellular distribution of MRTF-A in RPE-1 cells, as well as the extent of subretinal fibrosis in a mouse model, were determined by immunofluorescence analysis. Expression of α-smooth muscle actin (α-SMA), collagen type I (COL1), connective tissue growth factor (CTGF), and paxillin was examined by immunoblot analysis or reverse transcription and quantitative polymerase chain reaction analysis, whereas that of pro-matrix metalloproteinase-2 (MMP-2) was assessed by gelatin zymography.

Results: The MRTF-A signaling inhibitor CCG-1423 suppressed RPE-1 cell migration in a concentration-dependent manner. Transforming growth factor-beta (TGF-β2) induced MRTF-A translocation from the cytoplasm to the nucleus of RPE-1 cells, and this effect was attenuated by CCG-1423. TGF-β2 up-regulated the abundance of α-SMA, paxillin, and pro-MMP-2 proteins as well as the amounts of α-SMA, COL1, and CTGF mRNAs in a manner sensitive to inhibition by CCG-1423. Finally, intravitreal injection of CCG-1423 markedly attenuated the development of subretinal fibrosis induced by photocoagulation in vivo.

Conclusions: Our results implicate MRTF-A in EMT of RPE cells and in the development of subretinal fibrosis in vivo, suggesting that MRTF-A is a potential therapeutic target for retinal diseases characterized by subretinal fibrosis.

MeSH terms

  • Actins / metabolism
  • Anilides / pharmacology*
  • Animals
  • Benzamides / pharmacology*
  • Cell Movement / physiology
  • Collagen Type I / metabolism
  • Connective Tissue Growth Factor / metabolism
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Epithelial-Mesenchymal Transition / physiology*
  • Female
  • Fibrosis
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Matrix Metalloproteinase 2 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Real-Time Polymerase Chain Reaction
  • Retina / pathology
  • Retinal Pigment Epithelium / metabolism*
  • Trans-Activators / antagonists & inhibitors*
  • Trans-Activators / metabolism

Substances

  • ACTA2 protein, human
  • Actins
  • Anilides
  • Benzamides
  • CCG 1423
  • CCN2 protein, human
  • Collagen Type I
  • MRTFA protein, human
  • Trans-Activators
  • Connective Tissue Growth Factor
  • Matrix Metalloproteinase 2