Inhibition of epithelial-mesenchymal transition in retinal pigment epithelial cells by a retinoic acid receptor-α agonist

Sci Rep. 2021 Jun 4;11(1):11842. doi: 10.1038/s41598-021-90618-4.

Abstract

Epithelial-mesenchymal transition (EMT) in retinal pigment epithelial (RPE) cells plays a key role in proliferative retinal diseases such as age-related macular degeneration by contributing to subretinal fibrosis. To investigate the potential role of retinoic acid receptor-α (RAR-α) signaling in this process, we have now examined the effects of the RAR-α agonist Am580 on EMT induced by transforming growth factor-β2 (TGF-β2) in primary mouse RPE cells cultured in a three-dimensional type I collagen gel as well as on subretinal fibrosis in a mouse model. We found that Am580 inhibited TGF-β2-induced collagen gel contraction mediated by RPE cells. It also attenuated the TGF-β2-induced expression of the mesenchymal markers α-smooth muscle actin, fibronectin, and collagen type I; production of pro-matrix metalloproteinase 2 and interleukin-6; expression of the focal adhesion protein paxillin; and phosphorylation of SMAD2 in the cultured RPE cells. Finally, immunofluorescence analysis showed that Am580 suppressed both the TGF-β2-induced translocation of myocardin-related transcription factor-A (MRTF-A) from the cytoplasm to the nucleus of cultured RPE cells as well as subretinal fibrosis triggered by laser-induced photocoagulation in a mouse model. Our observations thus suggest that RAR-α signaling inhibits EMT in RPE cells and might attenuate the development of fibrosis associated with proliferative retinal diseases.

MeSH terms

  • Actins / metabolism
  • Animals
  • Benzoates / pharmacology*
  • Cell Proliferation
  • Collagen / chemistry
  • Collagen / metabolism
  • Epithelial-Mesenchymal Transition / drug effects*
  • Female
  • Fibrosis
  • Interleukin-6 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Muscle, Smooth / metabolism
  • Phosphorylation
  • Retinal Pigment Epithelium / metabolism*
  • Retinoic Acid Receptor alpha / agonists*
  • Signal Transduction
  • Smad2 Protein / metabolism
  • Tetrahydronaphthalenes / pharmacology*
  • Trans-Activators / metabolism
  • Transforming Growth Factor beta2 / metabolism

Substances

  • Actins
  • Benzoates
  • Interleukin-6
  • Mrtfa protein, mouse
  • Retinoic Acid Receptor alpha
  • Smad2 Protein
  • Smad2 protein, mouse
  • Tetrahydronaphthalenes
  • Trans-Activators
  • Transforming Growth Factor beta2
  • Am 580
  • Collagen