bims-mideyd 2026-05-03 papers

Cells. 2026 Apr 19. pii: 725. [Epub ahead of print]15(8):

Retinal Pigment Epithelium Ageing: Cellular and Molecular Mechanisms of Long-Term Homeostasis and Age-Related Dysfunction.

Yijing Yang, Pei Liu, Jiangwei Li, Ying Deng, Li Xiao, Qinghua Peng, Jun Peng.

The retinal pigment epithelium (RPE) is a long-lived, highly polarised epithelial monolayer that performs essential functions in retinal homeostasis, including outer blood-retina barrier maintenance, visual cycle activity, metabolic exchange, phagocytic clearance of photoreceptor outer segments, and regulation of oxidative and immune balance. Because RPE cells persist for decades under conditions of sustained oxidative, metabolic, and phagocytic stress, this tissue provides a valuable model for examining how long-lived post-mitotic cells preserve function over time and how age-related dysfunction emerges when that balance weakens. Although much of the current literature on RPE ageing has been shaped by age-related macular degeneration (AMD), age-dependent change in the RPE should not be understood solely as a preclinical stage of disease. Rather, the ageing RPE offers a broader framework for studying cellular maintenance under chronic physiological load. In this review, we synthesise current evidence on RPE ageing across four interrelated domains: structural remodelling, mitochondrial and metabolic imbalance, proteostatic and lysosomal burden, and chronic inflammatory dysregulation. Across these processes, ageing in the RPE is expressed less as widespread cell loss than as progressive decline in cellular organisation, buffering capacity, and functional precision. Structural irregularity, altered mitochondrial regulation, incomplete degradative clearance, and persistent low-grade inflammatory signalling together reduce the ability of the RPE to maintain long-term homeostasis and increase vulnerability to age-related retinal dysfunction. We further argue that ageing in the RPE is best understood not as abrupt failure of isolated pathways, but as gradual loss of system coherence among interacting homeostatic systems that remain active while operating under increasing constraint. This view helps integrate diverse cellular and molecular findings and highlights the RPE as an informative model for understanding ageing in long-lived post-mitotic tissues.

Keywords: age-related retinal dysfunction; ageing; cellular homeostasis; inflammation; long-lived cells; mitochondrial dysfunction; proteostasis; retinal pigment epithelium

DOI: https://doi.org/10.3390/cells15080725

Free Radic Res. 2026 Apr 29. 1-19

Proteomic insights into nepetin-mediated protection against oxidative stress in ARPE-19 cells.

Xi Chen, Peng Hao, Ping Lu, Ruifang Han, Zhixin Jiang, Li Jiang, Liming Wang, Zunfeng Liu, Xuan Li.

Oxidative stress is one of the crucial factors associated with the pathogenesis of age-related macular degeneration (AMD), particularly the degeneration of retinal pigment epithelium (RPE) cells. In this study, we identified nepetin, a natural flavonoid compound, as a potential inhibitor of hydrogen peroxide (H2O2)-induced ARPE-19 cell death. Pretreatment of nepetin significantly reduced intracellular generation of reactive oxygen species (ROS). Quantitative proteomics was applied to explore the underlying molecular response, revealing that 77 proteins were up-regulated, and 198 proteins were down-regulated significantly after nepetin treatment. Gene ontology (GO) analysis and the protein-protein interaction (PPI) network analysis showed that heme oxygenase 1 (HO-1), Kelch-like ECH-associated protein 1 (KEAP1), Sequestosome 1 (SQSTM1)/p62, and glucose-regulated protein 78 (GRP78) were associated with nepetin-mediated antioxidative responses. Western blotting confirmed the altered expression of these key proteins, with HO-1, p62, and GRP78 being upregulated and KEAP1 being downregulated. Immunofluorescence further showed nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, suggesting the involvement of Nrf2-related antioxidant signaling in nepetin-treated ARPE-19 cells. Although direct causal interactions were not established, the proteomic and bioinformatic analyses provide correlative and suggestive evidence that nepetin modulates key proteins within the oxidative stress response network. Based on our previous research and the current study, nepetin exhibits both anti-inflammatory and antioxidative properties in RPE cells, and may have potential implications for the prophylaxis and treatment of AMD, particularly dry AMD.

Keywords: Nrf2; RPE cells; nepetin; oxidative stress; proteomics

DOI: https://doi.org/10.1080/10715762.2026.2667438

Exp Cell Res. 2026 Apr 25. pii: S0014-4827(26)00163-1. [Epub ahead of print] 115046

Matrix Stiffness Disrupts Tight Junction Integrity in Retinal Pigment Epithelial Cells via YAP1-Mediated Autophagy Suppression.

Songtao Wang, Yu Zhang, Ning Yang, Jinrong Cui, Jinsong Zhao.

BACKGROUND: The extracellular matrix (ECM) of retinal pigment epithelial (RPE) cells undergoes progressive stiffening during aging and under pathological conditions. However, how such mechanical effects affect RPE cell function remain incompletely understood. This study aims to investigate the effect of stiffness of ECM on autophagy in RPE cells and its regulatory role on tight junctions.
METHODS: ARPE-19 cells were cultured on polyacrylamide hydrogel substrates with low (5 kPa) and high (40 kPa) stiffness. The expression and subcellular localization of tight junction proteins and autophagy-related markers were assessed by Western blotting, quantitative PCR, and immunofluorescence staining. Autophagy was pharmacologically modulated using the autophagy activator rapamycin and the inhibitor chloroquine to evaluate the effects of autophagy on tight junction integrity. In addition, knockdown of Yes-associated protein 1(YAP1) using shRNA to investigate its role in ECM stiffness-mediated regulation of autophagy and tight junction alterations.
RESULTS: Polyacrylamide hydrogel substrates with low stiffness (5 kPa) and high stiffness (40 kPa) had no significant effect on the growth or proliferation of ARPE-19 cells. High-stiffness substrates markedly suppressed autophagic activity in ARPE-19 cells and downregulated the expression of tight junction proteins zonula occludens-1 (ZO-1), Occludin, and Claudin-19, resulting in disruption of tight junction integrity. Pharmacological inhibition of autophagy further exacerbated tight junction damage, whereas autophagy activation partially reversed the tight junction impairment induced by high matrix stiffness. Moreover, knockdown of YAP1 substantially attenuated the inhibitory effects of high stiffness on autophagy and tight junction protein expression.
CONCLUSION: Increased ECM stiffness impairs tight junction integrity in ARPE-19 cells through a YAP1-mediated suppression of autophagy.

Keywords: autophagy; retinal pigment epithelial cell; tight junction; yes-associated protein 1

DOI: https://doi.org/10.1016/j.yexcr.2026.115046

bioRxiv. 2026 Apr 14. pii: 2026.04.11.717944. [Epub ahead of print]

Using Patient iPSC-derived Retinal Pigment Epithelial Cells to Evaluate Differential Susceptibility to MEK Inhibitor-Associated Retinopathy.

Lola P Lozano, Timothy M Boyce, Andrew P Groves, Henry L Keen, Culver Boldt, Robert F Mullins, Elaine M Binkley, Budd A Tucker.

Purpose: Compare the effect of MEK inhibition on iPSC-derived retinal pigmental epithelial (RPE) cells generated from a patient who developed MEK inhibitor-Associated Retinopathy (MEKAR) versus a patient who did not develop retinopathy.
Design: Case-control.
Subjects: Two female patients with Neurofibromatosis Type 1 who were treated with MEK inhibitors. One patient developed MEKAR, the other did not.
Methods: RPE were generated from human induced pluripotent stem cells (hiPSCs) from these two patients. These hiPSC-derived RPE were treated with selumetinib for 10 days.
Main Outcome Measures: Phagocytic activity and changes in gene expression.
Results: As previously reported, there was a significant increase in internalized rhodopsin in phagocytosis assays, yet this was only found in hiPSC-derived RPE from the patient who developed MEKAR. Selumetinib decreased expression of genes related to fluid transport and cell volume, including aquaporins and solute transporters. At baseline, cells from the patients without MEKAR had higher expression of these genes. Interestingly, selumetinib-induced changes in gene expression only reached statistical significance in cells from the patient who did not develop MEKAR, suggesting these changes may be a compensatory protective mechanism. Patients susceptible to forming MEKAR may have increased phagocytosis without a compensatory change in expression of genes related to fluid flux, thereby inhibiting their ability to transport fluid out of the subretinal space.
Conclusions: MEK inhibitor-Associated Retinopathy may only affect susceptible patients whose retinal pigment epithelium cannot sufficiently regulate expression of genes related to fluid transport and cell volume, altering the ability of these cells to properly function.

DOI: https://doi.org/10.64898/2026.04.11.717944