Phillyrin Mitigates Apoptosis and Oxidative Stress in Hydrogen Peroxide-Treated RPE Cells through Activation of the Nrf2 Signaling Pathway

Abstract

Oxidative stress-induced dysfunction or apoptosis in retinal pigment epithelial (RPE) cells is an important cause of dry age-related macular degeneration (AMD). Although phillyrin has been shown to exert significant antioxidant effects, the underlying mechanism of action remains unclear. The purpose of this study was to investigate the protective effect of phillyrin on hydrogen peroxide- (H2O2-) induced oxidative stress damage in RPE cells and the potential mechanism involved. It was found that phillyrin significantly protected RPE cells from H2O2 cytotoxicity. Furthermore, phillyrin alleviated oxidative stress-induced apoptosis via inhibition of endogenous and exogenous apoptotic pathways. Compared with the H2O2-treated group, the expressions of cleaved caspase-3, cleaved caspase-9, cleaved polymerase (PARP), death receptor Fas, and cleaved caspase-8, as well as Bax/Bcl-2 ratio were decreased in RPE cells after the phillyrin intervention. In addition, phillyrin reversed the oxidative stress-induced reductions in superoxide dismutase (SOD) and glutathione (GSH) levels and annulled the elevations in reactive oxygen species (ROS) and malondialdehyde (MDA), thereby restoring oxidant-antioxidant homeostasis. Phillyrin treatment upregulated the expressions of cyclin E, cyclin-dependent kinase 2 (CDK2), and cyclin A and downregulated the expressions of p21 and p-p53, thereby reversing the G0/G1 cell cycle arrest in H2O2-treated RPE cells. Pretreatment with phillyrin also increased the expressions of nuclear factor-erythroid 2-related factor 2 (Nrf2), total Nrf2, heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductases-1 (NQO-1) in RPE cells and inhibited the formation of Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 protein complex. Thus, phillyrin effectively protected RPE cells from oxidative stress through activation of the Nrf2 signaling pathway and inhibition of the mitochondria-dependent apoptosis pathway.

Deletion of Mitochondrial Translocator Protein (TSPO) Gene Decreases Oxidative Retinal Pigment Epithelial Cell Death via Modulation of TRPM2 Channel

“…A mitochondria protein of the cellular outer membrane in the mitochondria of several cells, including ARPE19 is TSPO. Accumulating evince indicates that the presence of TSPO participated the modulations of Ca 2+ homeostasis and mitochondrial fROS generation [10,11]. The deletion of TSPO gene provides to study the action of TSPO on the levels of apoptosis, ADPR, Mito-fROS and apoptosis via the stimulation of Ca 2+ permeable channels in the models of cell culture [40][41][42][43].…”

“…The dry AMD isn’t totally treated by the current drugs. However, accumulation data indicate that inhibition of excessive fROS generation in the membranes of retinal mitochondria is a reasonable way for the treatment of dry AMD disease [ 1 , 10 , 11 ].…”

Genistein Protects Epilepsy-Induced Brain Injury Through Regulating The JAK2/STAT3 and Keap1/Nrf2 Signaling Pathways in The Developing Rats

“…Under physiological conditions, Keap1 combines with and inhibits Nrf2. Under the in uence of external oxidative stressors, Nrf2 is decoupled with Keap1 and combined with the antioxidant response element ARE to activate the Nrf2 signaling pathway, thereby increasing the expression of antioxidant proteins HO-1, SOD, NQO1, etc., and reducing oxidative damage and accumulation of toxicity metabolites [49,50] . In a study by Wang et al…”

Chinese Medicine PaBing-II Protects Human iPSC Derived Dopaminergic Neurons from Oxygen Stress

“…When the occurrence of oxidative stress, Nrf2 phosphorylation, and Keap1 protein translocation into the uncoupling combine with ARE in the nucleus, regulation on downstream target genes, such as Heme Oxygenase-1 (HO-1) and NAD(P)H quinone dehydrogenase 1 (NQO1), is induced, to enhance the process of detoxi cation and antioxidant ability of cells [29][30][31]. In vitro experiments have also shown that the upregulation of HO-1 and NQO1 can protect cells against oxidative damage of glutamic acid, hydrogen peroxide, and amyloid beta-protein [32][33][34].…”