Transforming growth factor-β (TGF-β) plays a crucial role in the development of epithelial to mesenchymal transition (EMT) and fibrosis, particularly in an ocular disorder such as proliferative vitreoretinopathy (PVR). However, the key molecular mechanism underlying its pathogenesis remains unknown. In the present study, using cultured ARPE-19 cells, we determined that TGF-β initiates a signaling pathway through extracellular signal-regulated kinase (ERK)-mammalian target of rapamycin complex 1 (mTORC1) that stimulates trans-differentiation and fibrosis of retinal pigment epithelium. Blocking this pathway by a TGF-βRI, ERK or mTORC1 inhibitor protected cells from EMT and fibrotic protein expression. TGF-β1 treatment increased reactive oxygen species (ROS) via NOX4 upregulation, which acts downstream of ERK and mTORC1, as the ROS scavenger N-acetylcysteine and a pan-NADPH oxidase (NOX) inhibitor DPI dissipated excess ROS generation. TGF-β1-induced oxidative stress resulted in EMT and fibrotic changes, as NAC and DPI prevented α-SMA, Col4α3 expression and cell migration. All these inhibitors blocked the downstream pathway activation in addition to clearly preventing the activation of its upstream molecules, indicating the presence of a feedback loop system that may boost the upstream events. Furthermore, the FDA-approved drug trametinib (10 nM) blunted TGF-β1-induced mTORC1 activation and downstream pathogenic alterations through ERK1/2 inhibition, which opens a therapeutic avenue for the treatment of PVR in the future.
|Number of pages||6|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - 2020 Aug 27|
Bibliographical noteFunding Information:
This work was supported by the Medical Research Center Program (2017R1A5A2015369) from the Ministry of Science and ICT, and the Korea Health Technology R&D Project through the KHIDI (HI18C2196) from the Ministry of Health & Welfare, and Myung Sun Kim Memorial Foundation (2016).
This work was supported by the Medical Research Center Program ( 2017R1A5A2015369 ) from the Ministry of Science and ICT , and the Korea Health Technology R&D Project through the KHIDI ( HI18C2196 ) from the Ministry of Health & Welfare , and Myung Sun Kim Memorial Foundation (2016) .
© 2020 Elsevier Inc.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology