Abstract
Purpose :
Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a predominant pathological process underlying fibrotic cataract, including posterior capsular opacification (PCO) and anterior subcapsular cataract (ASC). Coactivators are a heterogeneous family of transcriptional regulators that are essential to fine-tune numerous cellular processes. Proliferator-activated receptor gamma coactivator-1α (PGC1A) is presently described as a master regulator of mitochondrial biogenesis and function. The aim of the present study was to evaluate the role and mechanism of PGC1A in EMT of LECs and lens epithelial fibrosis.
Methods :
TGFβ2 was used at the concentration of 10ng/ml for 1-3 days to induce EMT of human lens epithelial explants (HLEEs), primary rabbit LECs and whole rat lenses. RNA-sequencing was conducted to explore genetic changes during fibrosis of HLEEs. Loss- and gain-of-function studies were performed in primary rabbit LECs or rat lenses to investigate roles and mechanisms of PGC1A in EMT. Expression of PGC1A, EMT markers (FN, α-SMA, E-cad, ZO-1), total and phosphorylated Smad2/3 were analyzed by Western blot, RT-qPCR or immunofluorescent staining. Mitochondrial fusion (MFN1, MFN2) and fission (DRP1) protein were analyzed by Western blot. Cell migration was determined by wound healing assay. Rat lenses were photographed under a stereoscope. Cell morphology and organization were observed after Hematoxylin and Eosin staining.
Results :
Induction of EMT of LECs using TGFβ2 suppressed PGC1A expression and mitochondrial function. Overexpression of PGC1A protected LECs from EMT through inhibiting Smad2/3 phosphorylation and nuclear translocation. TGFβ2-induced proliferation and migration of LECs caused fibrosis of rat lenses, while knockdown of PGC1A promoted migration ability of LECs and lead to earlier-formed lens fibrotic plaques. Mitochondrial fusion was impaired while mitochondrial fission was facilitated during TGFβ2-induced EMT, which were restored by upregulation of PGC1A.
Conclusions :
Our experiment confirms that PGC1A maintains lens transparency by attenuating TGFβ2-induced EMT in LECs via inhibiting the Smad2/3 signal transduction and also implies that maintaining the balance of mitochondrial dynamics might be a promising strategy for preventing and treating fibrotic cataract.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.