Abstract
Purpose :
In this study, we aimed to investigate the potential roles and regulatory mechanisms of TGF-β in hyperglycemia-induced oxidative damage of RGCs in vitro.
Methods :
We cultured a retinal ganglion cell line (RGC-5) in mannitol-balanced 5.5 mM, 25 mM, 50 mM and 100 mM D-glucose media, and focused on oxidative stress pathway also combined with hydrogen peroxide (H2O2), further analyzed TGF-β influence on retinal neurodegenerations by several cell functional assays, such as ROS detection, GSH content assays and high resolution respirometry, immunofluorescence, and immunoblotting analysis combined with TGF-β knockdown.
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Results :
TGF-β expression was upregulated in RGCs after hyperglycemia treatment. Functional experiments showed that knockdown of TGF-β enhanced the production of reactive oxygen species (ROS) in high glucose concentration groups. In contrast, TGF-β overexpression had the opposite effects and protected against hyperglycemia-induced apoptosis. Moreover, we found that high glucose promoted the accumulation of nuclear factor erythroid 2-related factor (Nrf2) and increased the activity of antioxidant pathways. In addition, the results showed that the promoting effect of TGF-β on antioxidant signaling was associated with activation of heme oxygenase-1 (HO-1) and aldehyde dehydrogenase 3A1 (ALDH3A1), which are stress-response proteins. Furthermore, hyperglycemia-induced generation of ROS reduced by the overexpression of TGF-β1. When we combined the two oxidative stress-inducible factors, hyperglycemia, and H2O2 hypoxia, the data revealed that the tolerance to H2O2 in high glucose concentration became lower than the control group, implied that when patients in diabetes combine with glaucoma state, the RGCs will damage more serious than those whose plasma glucose level is in control.
Conclusions :
Taken together, these results demonstrated that TGF-β protects RGCs from hyperglycemia-induced damage by promoting the activation of Nrf2/HO-1 signaling and ALDH3A1 expression balanced by HIF-1α signaling, suggesting a potential anti-diabetic therapy for the treatment of diabetic retinopathy.
This is a 2020 ARVO Annual Meeting abstract.