HO-1-Mediated Autophagic Restoration Protects Lens Epithelial Cells Against Oxidative Stress and Cellular Senescence

KEAP1-NRF2/HO-1 Pathway Promotes Ferroptosis and Neuronal Injury in Schizophrenia

BACKGROUND

This study investigates the role of the KEAP1-NRF2/HO-1 signaling pathway in inducing ferroptosis and contributing to neuronal damage in schizophrenia.

METHODS

We retrieved schizophrenia-related data and ferroptosis-related genes from the RNA microarray dataset GSE27383 and FerrDB database, respectively. Bioinformatics data identified KEAP1 as a downregulated gene, which was validated using qRT-PCR and Western blot. We assessed intracellular Fe2⁺ content, MDA levels, GSH, and GPX4 in the prefrontal cortex and peripheral blood mononuclear cells (PBMCs) of patients with schizophrenia. Cortical interneurons (cINs) were generated from human-induced pluripotent stem cells (hiPSCs) of patients with schizophrenia and used to explore KEAP1 alterations during neurodevelopment. In addition, KEAP1 overexpression was induced in cINs via transfection with pcDNA KEAP1. The intracellular Fe⁺ levels, oxidative stress indicators, lipid peroxidation, and inflammatory cytokines were measured after transfection. To investigate molecular mechanisms, KI696-a high-affinity probe that disrupts the KEAP1-NRF2 interaction-was applied, and changes in oxidative stress, lipid peroxidation (C11-BODIPY staining), iron metabolism, and inflammatory pathways were evaluated.

RESULTS

Patients with schizophrenia exhibited underexpression of KEAP1, a key regulator of ferroptosis, along with elevated intracellular Fe2⁺ levels and increased MDA concentrations, indicating enhanced lipid peroxidation and oxidative stress. Reduced GPX4 activity and GSH levels were also observed, suggesting an increased susceptibility to ferroptosis. To further explore this, cINs derived from hiPSCs of patients with schizophrenia were studied. These cells showed decreased KEAP1 expression. Overexpression of KEAP1 in cINs led to a reduction in intracellular Fe2⁺ concentrations and oxidative damage, highlighting KEAP1's regulatory role in ferroptosis. In addition, treatment with KI696 induced significant alterations in pathways related to oxidative stress, iron metabolism, antioxidant defenses, and inflammation.

CONCLUSION

Our findings indicate that the KEAP1-NRF2/HO-1 pathway contributes to ferroptosis and neuronal injury in schizophrenia.

Sirtuin 1 Suppresses Hydrogen Peroxide-Induced Senescence and Promotes Viability and Migration in Lens Epithelial Cells by Inhibiting Forkhead Box Protein O1/Toll-Like Receptor 4 Pathway

Age-related cataracts (ARCs) are associated with increased oxidative stress and cellular senescence. Our objective is to investigate the function of Sirtuin 1 (SIRT1) within ARCs. In ARCs tissues and H2O2-treated lens epithelial cells (LECs), the expression levels of SIRT1 were examined. Senescence-associated β-galactosidase (SA-β-gal) staining was employed to evaluate cellular senescence. The Cell Counting Kit-8 assay was employed to measure viability. A wound healing assay was performed to assess migratory capacity in LECs. Oxidative stress-related indicators were determined by enzyme-linked immunosorbent assay kits. Additionally, the Coxpresdb and GeneCards databases were utilized to identify downstream pathways of SIRT1 in ARCs. The expression levels of protein and mRNA were detected using western blot and real-time quantitative polymerase chain reaction, respectively. The expression of SIRT1 was downregulated in ARCs tissues with an increase in reactive oxygen species. In H2O2-induced LECs, SIRT1 was downregulated and its overexpression inhibited oxidative stress and cellular senescence while promoting viability and migration. Furthermore, FoxO1/TLR4 pathway was screened out as the key pathway of SIRT1, which was activated in H2O2-induced LECs senescence. Overexpression of SIRT1 suppressed FoxO1/TLR4 pathway. Further research demonstrated that the activation of FoxO1/TLR4 pathway reversed the inhibitory role of SIRT1 in oxidative stress-induced cellular senescence and the promotion effect of SIRT1 on viability and migration in H2O2-induced LECs. SIRT1 inhibits oxidative stress-induced cellular senescence and promotes the viability and migration in H2O2-induced LECs via suppressing FoxO1/TLR4 pathway.

Slit2 Promotes H2O2-Induced Lens Epithelial Cells Oxidative Damage and Age-Related Cataract

PURPOSE

To analyze the role of Slit2 in lens epithelial cell oxidative damage and its underlying mechanism.

METHODS

Human lens epithelial cells (SRA01/04 cells) and rat transparent lens were cultured with H2O2 to establish cell oxidative stress models and rat cataract models. Immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot assays were employed to detect Slit2 levels within age-related cataracts(ARC) lens anterior capsule samples, rat cataract models, and cell oxidative stress models. In this study, qRT-PCR and Western blot assays were performed to derermine E-cadherin, N-cadherin, occludens1(ZO-1), α-SMA(α‑smooth muscle actin), Bcl-2, Bax, p-AKT, and AKT levels. In addition, Flow cytometry were performed to examine reactive oxygen species (ROS) and cell apoptosis. Cell viability, invasion, and migration were detected by CCK8, Transwell, and Wound healing.

RESULTS

Increased expression of Slit2 was found in ARC lens anterior capsule samples, H2O2-induced rat cataract models, and Human lens epithelial cells (HLECs) oxidative stress models. H2O2 significantly increased cell apoptosis and ROS generation, also accelerating cell migration, invasion, and epithelial-mesenchymal transition (EMT). In addition, H2O2 treatment repressed AKT phosphorylation and cell viability. Knock-down of Slit2 promoted cell viability and AKT phosphorylation levels, as well as repressed cell invasion, migration, apoptosis, ROS production and EMT.

CONCLUSION

Slit2 promoted lens epithelial cells oxidative stress damage via the AKT signalling pathways, providing a novel insight in ARC treatment.

The Occurrence of Senescence in the Arteriovenous Fistula in the Rat

Key Points

The rat arteriovenous fistula (AVF) model exhibits marked upregulation of p16Ink4a and p21Cip1 and multiple markers of senescence. Fisetin, an established vasoprotective senolytic agent, when administered for 3 weeks, increases AVF blood flow and AVF outward remodeling. Heme is shown to be a novel prosenescence metabolite, and when chronically administered, it decreases AVF blood flow.

Background

Maturational failure of dialysis arteriovenous fistulas (AVFs) not uncommonly occurs and is of considerable and timely importance. Our prior studies demonstrate that senescence, a phenotypic process that promotes vascular and other diseases, occurs in the murine AVF. In this study, we examined whether senescence also occurs in the rat AVF model and the effect of compounds that inhibit or accelerate senescence.

Methods

The rat AVF was created in the femoral vessels by an end vein-side artery anastomosis. In the AVF, we assessed the expression of critical drivers of senescence, specifically, the cell cycle inhibitors p16Ink4a and p21Cip1, and such indices of a senescence phenotype as senescence-associated β -galactosidase (SA-β -gal) activity, SA-β -gal staining, and a senescence-associated secretory phenotype. We examined the effects of compounds that retard or accelerate senescence on AVF blood flow.

Results

The AVF evinced upregulation of p16Ink4a and p21Cip1 when assessed 3 days after AVF creation. The AVF also demonstrated increased SA-β -gal activity in the artery and vein; staining for SA-β -gal in the AVF artery, anastomosis, and vein; and a prominent senescence-associated secretory phenotype. Fisetin, an established senolytic that is protective in other models of vascular injury, when administered for 3 weeks, increased AVF blood flow and outward remodeling. Hemin, when administered for 3 weeks, decreased AVF blood flow. We demonstrate that hemin is a novel inducer of a senescence phenotype in endothelial cells, as reflected by several senescence indices. However, when administered relatively acutely (for 5 days), hemin increased AVF blood flow by heme oxygenase–dependent mechanisms because the latter was entirely prevented by a competitive inhibitor of heme oxygenase activity.

Conclusions

The rat AVF exhibits senescence within 3 days of its creation. Chronic administration of a senolytic compound (fisetin) increases AVF blood flow, whereas chronic administration of a prosenescence compound (hemin) decreases AVF blood flow.

METTL3-mediated m6A modification of SIRT1 mRNA affects the progression of diabetic cataracts through cellular autophagy and senescence

BACKGROUND

The increasing incidence of diabetes mellitus has established diabetic cataracts (DC) as a significant worldwide public health issue. The mechanisms underlying DC remain unknown, and effective prevention and treatment strategies are lacking. Accordingly, we aimed to explore the role and mechanism behind N6-methyladenosine (m6A) in DC progression.

METHODS

Methyltransferase-like 3 (METTL3), p21, Beclin1, LC3, and p62 expression levels were measured in human tissues. This study assessed total m6A levels and common m6A-regulated biomarkers in both in vitro and in vivo DC models. Autophagy flux was detected in vitro through Ad-mCherry-GFP-LC3B and Monodansylcadaverine (MDC) staining. Cellular senescence was assessed utilizing the senescence-associated β-galactosidase (SA-β-Gal) assay. Furthermore, the effect of METTL3 on SIRT1 mRNA modification was demonstrated, and its mechanism was elucidated using RT-qPCR, western blot, RNA stability assays, and RIP analysis.

RESULTS

METTL3, p21, and p62 expression levels were elevated in lens epithelial cells (LECs) from DC patients, while Beclin1 and LC3 levels were reduced. Silencing METTL3-mediated m6A modifications restored high-glucose-induced autophagy inhibition and prevented premature senescence in LECs. Notably, SIRT1720 and Metformin significantly enhanced autophagosome generation and delayed cellular senescence. The m6A-reading protein YTHDF2 bound to m6A modifications, and YTHDF2 silencing significantly reduced METTL3-mediated SIRT1 inactivation.

CONCLUSIONS

METTL3 induces senescence in DC by destabilizing SIRT1 mRNA in an m6A-YTHDF2-dependent manner. The METTL3-YTHDF2-SIRT1 axis is a key target and potential pathogenic mechanism in DC.

Clinical and genetic risk factors underlying severe consequence identified in 75 families with unilateral high myopia

BACKGROUNDS

Unilateral high myopia (uHM), commonly observed in patients with retinal diseases or only with high myopia, is frequently associated with amblyopia with poor prognosis. This study aims to reveal the clinical and genetic spectrum of uHM in a large Chinese cohort.

METHODS

A total of 75 probands with simplex uHM were included in our Pediatric and Genetic Eye Clinic. Patients with significant posterior anomalies other than myopic fundus changes were excluded. Variants were detected by exome sequencing and then analyzed through multiple-step bioinformatic and co-segregation analysis and finally confirmed by Sanger sequencing. Genetic findings were correlated with associated clinical data for analysis.

RESULTS

Among the 75 probands with a mean age of 6.21 ± 4.70 years at the presentation, myopic fundus of C1 and C2 was observed in 73 (97.3%) probands. Surprisingly, specific peripheral changes were identified in 63 eyes involving 36 (48.0%) probands after extensive examination, including peripheral retinal avascular zone (74.6%, 47/63 eyes), neovascularization (54.0%), fluorescein leakage (31.7%), peripheral pigmentary changes (31.7%), and others. Exome sequencing identified 21 potential pathogenic variants of 13 genes in 20 of 75 (26.7%) probands, including genes for Stickler syndrome (COL11A1 and COL2A1; 6/20), FEVR (FZD4, LRP5, and TSPAN12; 5/20), and others (FBN1, GPR179, ZEB2, PAX6, GPR143, OPN1LW, FRMD7, and CACNA1F; 9/20). For the peripheral retinal changes in the 20 probands, variants in Stickler syndrome-related genes were predominantly associated with retinal pigmentary changes, lattice degeneration, and retinal avascular region, while variants in genes related to FEVR were mainly associated with the avascular zone, neovascularization, and fluorescein leakage.

CONCLUSIONS

Genetic defects were identified in about one-fourth of simplex uHM patients in which significant consequences may be hidden under a classic myopic fundus in up to half. To our knowledge, this is the first systematic genetic study on simplex uHM to date. In addition to routine care of strabismus and amblyopia, careful examination of the peripheral retina and genetic screening is warranted for patients with uHM in order to identify signs of risk for retinal detachment and other complications and provide meaningful genetic counseling.