Aug 2026· Biochemical Pharmacology· pp.
118389
· 0 citations· 35 references
Medicine
TL;DR
The UCHL1/NRF2 axis may represent a therapeutic target in DR and co-immunoprecipitation and ubiquitination assays demonstrated that UCHL1 interacted with NRF2 and stabilized NRF2 by removing K48-linked polyubiquitin chains.
Abstract
Diabetic retinopathy (DR) is characterized by progressive retinal microvascular injury, with oxidative stress and ferroptosis increasingly recognized as key pathogenic contributors. This study investigated whether ubiquitin C-terminal hydrolase L1 (UCHL1) regulates retinal endothelial ferroptosis through stabilization of nuclear factor erythroid 2-related factor 2 (NRF2). Analysis of the GSE102485 dataset identified UCHL1 as a downregulated deubiquitinating enzyme in DR. Streptozotocin-induced type 1 diabetic mice and high glucose (HG)-induced human retinal capillary endothelial cells (HRCECs) were used, together with UCHL1 inhibition/knockdown, AAV-mediated UCHL1 overexpression, and NRF2 knockdown. UCHL1 expression was reduced in diabetic retinas and HG-induced HRCECs, accompanied by ferroptosis activation, mitochondrial injury, and endothelial dysfunction. Pharmacological inhibition or siRNA-mediated depletion of UCHL1 intensified oxidative stress, Fe2⁺ accumulation, lipid peroxidation, mitochondrial fragmentation, and cristae disruption, while impairing endothelial barrier integrity, migration, and tube formation. In vivo, LDN57444 aggravated retinal vascular leakage and fundus vascular abnormalities, whereas AAV-UCHL1 preserved retinal architecture and reduced vascular permeability. Mechanistically, co-immunoprecipitation and ubiquitination assays demonstrated that UCHL1 interacted with NRF2 and stabilized NRF2 by removing K48-linked polyubiquitin chains. Nuclear-cytoplasmic fractionation further showed that UCHL1 overexpression restored NRF2 abundance and increased nuclear NRF2 accumulation under HG conditions. Ferrostatin-1 rescued UCHL1 depletion-induced ferroptotic injury, whereas NRF2 knockdown abolished the protection conferred by UCHL1 overexpression. These findings highlight the UCHL1/NRF2 axis may represent a therapeutic target in DR.
Investigating the potential role of the RNA-binding protein human antigen R (HuR) in mediating ferroptosis during DR progression, as well as the protective effects of Procyanidin C1 (PC1), demonstrated that PC1 significantly alleviated oxidative stress and ferroptosis in both diabetic mice and high-glucose-treated BV2s.
Qun Liu, Song-Min Wang, Tao Jiao et al.· Experimental Eye Research· 0 citations
The FOXO6–SMURF2–NR4A1–NR4A1 axis critically regulates ferroptosis in RPE cells during DR, and this interaction critically regulates ferroptosis in RPE cells during DR.
Qiao Chen, Bo Su, Ke Xu et al.· Journal of cell communicatio...· 0 citations
High-glucose (HG) stress induces dysfunction of vascular endothelium, a key factor contributing to diabetic vascular complications, in part through ferroptosis. However, the mechanisms governing ferroptosis under these conditions remain partially understood. Herein, we identified circFBXO7 as a novel circular RNA that promotes ferroptosis and endothelial injury in human umbilical vein endothelial cells (HUVECs) and immortalized human aortic endothelial cells (iHAECs) treated with HG. Transcriptomic profiling revealed that circFBXO7 was markedly upregulated upon HG exposure and positively correlated with ferroptosis-related genes. Functional experiments showed that silencing circFBXO7 alleviated HG-induced cell death, restored migration and tube formation, and reduced oxidative stress, lipid peroxidation, Fe2+ accumulation, and mitochondrial damage. Mechanistically, circFBXO7 interacted with the transcription factor cellular promoter 2 (TFCP2) and promoted its ubiquitination and proteasomal degradation. Rescue experiments demonstrated that TFCP2 inhibition abolished the protective effects of circFBXO7 knockdown and sensitized endothelial cells to HG-induced ferroptosis. Overexpression of TFCP2 inhibited ferroptosis caused by HG treatment. Collectively, these findings identify a novel circFBXO7-TFCP2 regulatory axis linking metabolic stress to endothelial ferroptosis, providing new insight into the molecular basis of diabetic vascular dysfunction.
Background: Hypoxia-induced oxidative stress and ferroptosis contribute to blood–brain barrier dysfunction and neurovascular injury associated with ischemic stroke and neurodegenerative diseases. Luteolin, a naturally occurring flavonoid with potent antioxidant and anti-inflammatory activities, has emerged as a potential neuroprotective agent; however, its effects on hypoxia-induced ferroptosis in brain microvascular endothelial cells remain unclear. This study investigated the protective effects of luteolin and its association with changes in the PPARγ/FABP5/ALOX15 signaling pathway during hypoxia-induced ferroptotic injury. Methods: Human brain microvascular endothelial cells (HBEC-5i) were exposed to cobalt chloride (CoCl2) to establish an in vitro hypoxia model and subsequently treated with luteolin. Cell viability was assessed using the MTT assay. Intracellular Fe2+ accumulation, reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione (GSH/GSSG) levels were determined using biochemical assays. The expression of ferroptosis- and hypoxia-related proteins, including GPX4, ALOX15, FABP5, PPARγ, HIF-1α, and VEGF, was evaluated by Western blotting. Results: CoCl2-induced hypoxia significantly reduced cell viability and increased intracellular Fe2+ accumulation, ROS generation, lipid peroxidation, and ferroptosis-associated signaling in HBEC-5i cells. Hypoxic conditions upregulated ALOX15 and FABP5 expression while suppressing GPX4 and PPARγ levels. Luteolin treatment markedly attenuated these effects by restoring GSH/GSSG homeostasis, enhancing GPX4 expression, reducing ALOX15-mediated lipid peroxidation, and suppressing HIF-1α and VEGF expression. In addition, luteolin modulated the PPARγ/FABP5 signaling pathway, suggesting its involvement in the regulation of hypoxia-induced ferroptosis. Conclusions: Luteolin attenuates hypoxia-induced ferroptosis-associated changes in human brain microvascular endothelial cells by restoring redox homeostasis and is associated with coordinated modulation of the PPARγ/FABP5/ALOX15 pathway. These findings extend previous reports of the anti-ferroptotic effects of luteolin by providing evidence in brain microvascular endothelial cells under hypoxia-mimetic stress.
OBJECTIVES
To investigate whether AS-IV alleviates high glucose (HG)-induced podocyte ferroptosis and whether this effect is associated with the GSK3β/Nrf2/GPX4 axis.
METHODS
Differentiated MPC-5 podocytes were exposed to HG (30 mmol/L) with or without AS-IV, the GSK3β inhibitor LY2090314, or the ferroptosis inhibitor Ferrostatin-1 (Fer-1). An osmotic control (mannitol) was included. Cell viability was quantified with the CCK-8 assay. Levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH) and Fe²⁺ were measured. Lipid peroxidation was detected using C11-BODIPY 581/591. Mitochondrial morphology was examined by transmission electron microscopy and protein expression was analyzed by Western blot.
RESULTS
HG exposure induced podocyte injury, characterized by decreased viability, increased oxidative stress (elevated ROS, MDA and lipid ROS), GSH depletion, iron overload and mitochondrial damage. The osmotic control did not reproduce these effects. AS-IV or Fer-1 significantly attenuated the HG-induced damage and lipid peroxidation. At the molecular level, HG downregulated Nephrin, p-GSK3β (Ser9), Nrf2 and GPX4, while upregulating total GSK3β. AS-IV treatment partially reversed these protein expression changes and produced a protective pattern similar to that of LY2090314.
CONCLUSION
AS-IV alleviates HG-induced podocyte injury, possibly by suppressing ferroptosis and this protective effect may involve modulation of the GSK3β/Nrf2/GPX4 axis. The results offer new insights into DN pathogenesis and support AS-IV as a potential therapeutic candidate.
M. Gao, Hong Jiang, Kangya Lei et al.· Pakistan Journal of Pharmace...· 0 citations
Diabetic retinopathy, diabetic kidney disease, and diabetic peripheral neuropathy remain major causes of visual loss, kidney failure, pain, disability, and reduced quality of life despite improvements in glycemic and cardiovascular risk management. Oxidative stress, mitochondrial dysfunction, iron dyshomeostasis, lipid peroxidation, and sterile inflammation are shared features of these complications and converge on regulated cell-death programs. Ferroptosis is driven by iron-dependent phospholipid peroxidation when glutathione peroxidase 4 and complementary antioxidant systems are insufficient, whereas pyroptosis is an inflammatory lytic process executed by gasdermins after activation of inflammasome-associated or other inflammatory caspases. Nuclear factor erythroid 2-related factor 2 (NRF2) connects these pathways by regulating glutathione synthesis, lipid peroxide detoxification, iron handling, mitochondrial homeostasis, and redox-sensitive inflammatory signaling. Dietary polyphenols may influence this network through electrophilic or kinase-dependent NRF2 activation, preservation of the SLC7A11-glutathione-GPX4 axis, modulation of iron and lipid metabolism, and inhibition of NF-kappaB, TXNIP, NLRP3, caspase-1, and gasdermin signaling. This integrative review critically examines mechanistic, preclinical, and human evidence for these effects in the diabetic retina, kidney, and peripheral nerve. The strongest direct preclinical evidence currently concerns corilagin, resveratrol, isoquercetin, quercetin, epigallocatechin gallate, punicalagin, and selected anthocyanin-rich or phenolic extracts. Human studies suggest possible benefits for albuminuria, retinal edema, endothelial function, and neuropathic outcomes, but they rarely measure ferroptosis- or pyroptosis-specific biomarkers and their results are heterogeneous. The proposed ferroptosis–pyroptosis–NRF2 network should therefore be viewed as a biologically plausible integrative framework rather than a clinically validated linear pathway. Future trials require chemically characterized interventions, exposure biomarkers, tissue-relevant pharmacokinetics, prespecified regulated-cell-death panels, and clinically meaningful microvascular endpoints.
Unknown authors· Nutrients· 0 citations
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