Sulfiredoxin-1 protects retinal ganglion cells from high glucose-induced oxidative stress and inflammatory injury by potentiating Nrf2 signaling via the Akt/GSK-3β pathway

Abstract

Sulfiredoxin-1 (Srxn1) has been acknowledged as a remarkable pro-survival factor in the protection of cells against stress-induced damage. The persistent exposure of retinal ganglion cells (RGCs) to high glucose (HG) in diabetes induces cellular damage, which contributes to the onset of diabetic retinopathy, a severe complication of diabetes. So far, little is known about the role of Srxn1 in regulating HG-induced injury of RGCs. The goals of this work were to evaluate the possible relevance of Srxn1 in the modulation of HG-induced apoptosis, oxidative stress and inflammation of RGCs in vitro. Our data showed that HG exposure caused a marked decrease in Srxn1 expression in RGCs. The up-regulation of Srxn1 markedly decreased HG-evoked apoptosis, reactive oxygen species (ROS) generation and pro-inflammatory cytokine release in RGCs. On the contrary, the depletion of Srxn1 rendered RGCs more susceptible to HG-induced injury. Further data demonstrated that Srnx1 enhanced the activation of nuclear factor erythroid-2 (E2)-related factor 2 (Nrf2) signaling in HG-exposed RGCs associated with up-regulating the phosphorylation of Akt and glucogen synthase kinase-3β (GSK-3β). Notably, the inhibition of Akt abolished Srnx1-overexpression-mediated Nrf2 activation, while GSK-3β inhibition reversed Srnx1-depletion-mediated inactivation of Nrf2. In addition, Nrf2 inhibition partially abrogated Srnx1-mediated protective effects against HG-induced injury of RGCs. In summary, these data demonstrate that the overexpression of Srxn1 protects RGCs from the HG-induced injury of RGCs by enhancing Nrf2 signaling via modulation of Akt/GSK-3β axis. Our work highlights that the Srxn1-mediated Akt/GSK-3β/Nrf2 axis may exert a possible role in regulating RGC injury of diabetic retinopathy.