Astragaloside-IV alleviates high glucose-induced ferroptosis in retinal pigment epithelial cells by disrupting the expression of miR-138-5p/Sirt1/Nrf2

Abstract

Astragaloside-IV (AS-IV) (C 41 H 68 O 14 ) is a high-purity natural product extracted from Astragalus , which has demonstrated biological activities. However, the effect of AS-IV on retinal pigment epithelial (RPE) cells in diabetic retinopathy (DR) remains unclear. In this study, high glucose (HG) was shown to promote ARPE-19 RPE cell death, increase the contents of reactive oxygen species (ROS) and oxidized glutathione (GSSG), and enhance lipid peroxidation density of mitochondrial membrane. In contrast, AS-IV decreased glutathione (GSH) content, mitochondria size and ridge. Addition of iron death inhibitor Ferrostatin-1 (Fer-1) to RPE cells decreased cell dead rate, thus indicating that HG-induced mitochondrial damage occurred due to ferroptosis. AS-IV alleviated HG-induced RPE cell damage. Furthermore, HG decreased levels of silent information regulator 1 (Sirt1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in the nucleus of RPE cells; AS-IV could alleviate these effects and increased expression of glutathione peroxidase 4 (GPX4), glutamate cysteine ligase (GCLM) and glutamate cysteine ligase catalytic subunit (GCLC), which are Nrf2 downstream genes. Mechanistically, AS-IV was shown to alleviate the effects of HG by increasing mir-138-5p expression in RPE cells and promoting expression of Sirt1 and Nrf2 in the nucleus. Transfection of mir-138-5p agonist inhibited the regulatory effects of AS-IV on Sirt1 and Nrf2, accompanied by decreased GPX4, GCLM and GCLC levels, and restoration of ferroptosis-related changes. Collectively, HG increased ferroptosis rate in RPE cells. In addition, AS-IV inhibited miR-138-5p expression, subsequently increasing Sirt1/Nrf2 activity and cellular antioxidant capacity to alleviate ferroptosis, resulting decreased cell death, which potentially inhibits the DR pathological process.

Role of Mitochondria in Retinal Pigment Epithelial Aging and Degeneration

“…In these cells, reduced ATP production and mitochondrial membrane potential, increased ROS, accumulation of damaged, fragmented and vesiculated mitochondria, and mitophagic flux to lysosomes, were observed. NaIO 3 and high glucose have also been shown to induce RPE ferroptosis, which can be repressed by ferroptosis inhibitors (Liu et al, 2021;Tang et al, 2022). In an independent study, high glucose promoted RPE apoptosis and inhibited cell proliferation and mitophagy by inactivating ROS/Pink1/Parkin signal pathway (Zhang et al, 2019).…”

Ferroptosis: A Potential Therapeutic Target in Acute Kidney Injury

“…Ferroptosis could be triggered during development or during normal homeostatic tissue turnover, by the accumulation of (1) iron [ 25 , 26 , 27 , 28 , 29 ] or (2) PUFAs [ 17 ], or by (3) the depletion of the antioxidant glutathione (GSH) [ 30 ], decreased function of glutathione peroxidase 4 (GPX4), which mediates the reduction of lipid peroxides [ 31 , 32 ], or the activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase [ 33 , 34 , 35 ].…”

Targeting Novel Regulated Cell Death: Pyroptosis, Necroptosis, and Ferroptosis in Diabetic Retinopathy

“…Similarly, the expression of miR-138–5p is upregulated in RPE cells treated with high glucose, which reduces Sirt1/Nrf2 activity and antioxidant expression and ultimately induces RPE cell ferroptosis. Astragaloside-IV alleviates high glucose-induced ferroptosis in RPE cells by disrupting the expression of miR-138–5p/Sirt1/Nrf2( Tang et al, 2022 ). In addition, a novel miR-338–3p/SLC1A5 axis has been reported that regulates oxidative stress-mediated RPE cell ferroptosis to modulate DR progression.…”

“…Quercetin, resveratrol, germacrone and cryptochlorogenic acid all have been reported to have potential anti-ferroptosis properties in diabetes mellitus or its complications ( Yang and Yang, 2022 ). In a DR in vitro model, astragaloside-IV, a high-purity natural product extracted from Astragalus membranaceus, alleviates high glucose-induced ferroptosis in RPE cells by disrupting the expression of miR-138–5p/Sirt1/Nrf2( Tang et al, 2022 ). In addition, downregulation of TRIM46 increases RCEC resistance against high glucose-induced perroptosis.…”