Abstract
Purpose :
Oxidative stress plays a critical role in the pathogenesis of glaucoma and may induce retinal ganglion cell (RGC) damage. TGF-beta (TGF-β) has emerged as a neuroprotective protein against various insults. However, whether TGF-β exerts protective effects against oxidative stress-damaged RGCs remains unknown. In this study, we aimed to investigate the potential roles and regulatory mechanisms of TGF-β1/2 in hydrogen peroxide (H2O2)-induced oxidative damage of RGCs in vitro.
Methods :
We have established the cell viability at different concentrations and exposure durations of H2O2-treated RGCs, and also investigated the effects of H2O2 stimulation on cell apoptotic status, GSH content, oxygen consumption rate (OCR) and increased iROS levels on RGCs in different TGFβ expression conditions. In addition, to explore the potential of signal transduction in regulating oxidative damage in RGCs, we treated RGCs with H2O2-induced oxidative stress, and then detected changes in expression of Nrf2, Keap1, HIF-1α, ALDH3A1, HO-1, TGF-β1, and TGF-β2 proteins which in response by immunoblot analysis.
Results :
We found that TGF-β1/2 expression was upregulated in RGCs after H2O2 treatment. Functional experiments showed that knockdown of TGF-β1/2 reduced survival and enhanced apoptosis and production of reactive oxygen species (ROS). In contrast, TGF-β1 overexpression had the opposite effects. Moreover, we found that TGF-β1 expression promoted the accumulation of nuclear factor erythroid 2-related factor (Nrf2) and increased the activity of antioxidant pathways. In addition, we found that the promoting effect of TGF-β1 on antioxidant signaling was associated with activation of heme oxygenase-1 (HO-1) and aldehyde dehydrogenase 3A1 (ALDH3A1), which are stress-response proteins. Furthermore, ROS accumulation followed by overexpression of hypoxia-inducible factor (HIF-1α) caused mitochondrial damage and led to neurodegeneration.
Conclusions :
Taken together, these results demonstrated that TGF-β1 protects RGCs from oxidative stress-induced damage by promoting the activation of Nrf2/HO-1 signaling and ALDH3A1 expression balanced by HIF-1α signaling, suggesting a potential role of TGF-β1 in retinal degenerative disease.
This is a 2020 ARVO Annual Meeting abstract.