bims-mideyd 2025-11-23 papers

Am J Physiol Cell Physiol. 2025 Nov 17.

Role of Kir7.1 K+ channel in retinal pigment epithelium probed in a Kir7.1-M125R-expressing mutant mouse.

Erwin Vera, Juan Carlos Henao, L Pablo Cid, Francisco V Sepúlveda, Isabel Cornejo.

Eye disease-associated K+ channel Kir7.1 is highly expressed together with the Na+-K+ pump at the apical membrane of retinal pigment epithelial cells (RPE) which line the subretinal space (SRS). SRS K+ concentration ([K+]SRS) decreases from ~5 to 2 mM upon light stimulation. Kir7.1 is crucial in its buffering, with failure thought to be causal in visual disease mutations of its gene. The unusual inverse relation to [K+]o of its conductance, deemed essential for [K+]SRS buffering, relies on non-conserved outer pore methionine-125. We now probe the role of Kir7.1 in the visual process by generating Kir7.1-M125R mutant mice with the channel predicted to lack [K+]SRS buffering ability. RPE cell electrical properties and mouse electroretinograms (ERG) are assessed. Membrane potential of RPE cells was found to be dominated by K+, but while conductance decreased with increasing [K+]o in control cells, the reverse was true for cells of Kir7.1-M125R-expressing mice. ERG of mutant animals revealed a larger c-wave than in controls, consistent with the relative K+ permeabilities of the RPE. In contrast, there was no difference between the a- and b-waves of Kir7.1-M125R and control mice, suggesting normal functioning of photoreceptors and bipolar cells, and therefore retinal processing of the light signal. If, as predicted, [K+]SRS buffering is altered in mutant animals, this does not affect the retinal processing of the light signal. Other consequences of Kir7.1 malfunction, such as proposed function in photoreceptor outer segment recycling, must be involved in originating the disease phenotype associated with mutations in its gene.

Keywords: Photoreceptors; Potassium buffering

DOI: https://doi.org/10.1152/ajpcell.00690.2025

bioRxiv. 2025 Oct 05. pii: 2025.10.03.680301. [Epub ahead of print]

Modeling MEK inhibitor-Associated Retinopathy in vitro using human induced pluripotent stem cell-derived retinal pigment epithelial cells.

Lola P Lozano, Madeleine Jennisch, Renato Jensen, Jason A Ratcliff, Luke A Wiley, Brynnon Harman, Megan J Riker, Allison T Wright, Bradley A Erickson, H Culver Boldt, Timothy M Boyce, Robert F Mullins, Elaine M Binkley, Budd A Tucker.

Pharmacologic inhibitors of MEK are important anti-cancer drugs but can result in MEK inhibitor-Associated Retinopathy (MEKAR) in which vision is lost due to serous retinal detachments that form via an unknown mechanism. We hypothesized that the cause of this side effect is drug-induced dysfunction of retinal pigment epithelial (RPE) cells. To test this hypothesis, we used human induced pluripotent stem cell-derived RPE cells. We treated mature, hiPSC-derived RPE cells with selumetinib and measured impacts on RPE-specific function, structure, and gene expression. Selumetinib increases the ability of hiPSC-derived RPE to internalize bovine rod outer segments (1.9 vs 3.0, p=0.0024). It also decreases expression of aquaporin 1 during the first 10 days of treatment (2.7 vs 1.1, p=0.0015). It has no effect on the ability of hiPSC-derived RPE to maintain membrane integrity. Selumetinib alters gene expression of hiPSC-derived RPE, with significant changes in genes involved in transport of ions and small molecules regulating cell volume and lysosomal acidification. Selumetinib may lead to subretinal fluid accumulation by both increasing secretions into this space and decreasing outflow.

DOI: https://doi.org/10.1101/2025.10.03.680301

Sci Rep. 2025 Nov 18. 15(1): 40349

Extracellular matrix stiffness modulates angiogenic properties of the retinal pigment epithelium.

Lasse Wolfram, Melanie Schwämmle, Clara Gimpel, David A Merle, Jiaqi Tang, Simon J Clark, Daniel Böhringer, Günther Schlunck.

Physiological and pathological processes, such as aging and basal deposit aggregation in degenerative retinal diseases like age-related macular degeneration (AMD), alter the mechanical properties of Bruch's membrane (BrM). These mechanical changes in the extracellular matrix (ECM) significantly affect retinal pigment epithelial (RPE) cells, influencing their morphology, transcriptome and angiogenic behavior. ARPE-19 cells were cultured on hydrogels of physiological stiffness (30 and 80 kPa) and on conventional tissue culture plastic (TCP) for comparison. Gene expression was analyzed by droplet digital PCR (ddPCR), while protein-level changes were examined using immunofluorescence (IF), Western blotting (WB) and enzyme-linked immunosorbent assays (ELISA). Stiffness-dependent modulation of endothelial cells by RPE-conditioned media was investigated using in vitro angiogenesis assays. RPE cells cultured on softer substrates exhibited enhanced angiogenic properties, including increased expression of CD44 and vascular endothelial growth factor (VEGF). In contrast, stiffer substrates promoted antiangiogenic responses, associated with altered distribution of thrombospondin 1 (THBS1). These findings underscore the importance of ECM mechanics in modulating angiogenic signaling and highlight their potential relevance in retinal pathologies such as AMD. Local disruptions in adhesion or mechanical cues, potentially caused by basal deposits, may contribute to proangiogenic behavior even in the context of globally increased tissue stiffness with age.

Keywords: Age-related macular degeneration (AMD); Angiogenesis; Bruch’s membrane (BrM); Extracellular matrix (ECM); Retinal pigment epithelium (RPE); Tissue stiffness

DOI: https://doi.org/10.1038/s41598-025-27140-4

Exp Eye Res. 2025 Nov 19. pii: S0014-4835(25)00534-2. [Epub ahead of print] 110761

Dihydromyricetin Mitigates Oxidative Damage Induced by Mixed Phthalates via Nrf2 Activation in Experimental Models of Glaucoma.

Duncheng Xiao, Fan Yang, Mohan Li, Zhe Lu, Shouxin Xing, Song Wang, Tianchang Tao, Zhengxuan Jiang, Liming Tao.

PURPOSE: To evaluate the impact of combined Di(2-ethylhexyl) phthalate (DEHP) and Di-isodecyl phthalate (DiDP) exposure on retinal oxidative stress, and to assess the protective role of dihydromyricetin (DMY) via nuclear factor erythroid 2-related factor 2 (Nrf2) signaling.
METHODS: This study integrated epidemiological analysis from the National Health and Nutrition Examination Survey (NHANES) with in vitro and in vivo experiments. Generalized additive models and SHapley Additive exPlanations (SHAP) were used to assess the association between phthalate metabolites and glaucoma risk. Human primary retinal ganglion cells (RGCs) were exposed to DEHP/DiDP mixtures, and oxidative stress markers-reactive oxygen species (ROS), glutathione (GSH), and superoxide dismutase 1 (SOD1)-were measured. Nrf2 and mitogen-activated protein kinase (MAPK) pathway proteins were evaluated by Western blot. The effect of DMY was tested with and without the Nrf2 inhibitor ML385. Visual Evoked Potential (VEP) assessed retinal function in a mouse model of phthalate and ischemic injury.
RESULTS: DEHP and DiDP induced concentration-dependent cytotoxicity and oxidative stress by suppressing Nrf2/heme oxygenase-1 (HO-1) and activating MAPK signaling. DMY significantly restored antioxidant defenses and suppressed MAPK activation; these effects were abolished by Nrf2 inhibition. In vivo, DMY preserved visual evoked potential (VEP) responses, reflecting its protective effect on the optic nerve and post-retinal visual pathway. NHANES data supported a non-linear association between phthalate exposure and glaucoma risk.
CONCLUSIONS: DEHP and DiDP contribute to retinal neurodegeneration through oxidative stress and MAPK activation. DMY offers neuroprotection by activating Nrf2/HO-1 and suppressing MAPK signaling, suggesting therapeutic potential in environmentally induced glaucoma.

Keywords: Glaucoma; Neuroprotection; Oxidative Stress; Phthalate

DOI: https://doi.org/10.1016/j.exer.2025.110761

Front Cell Infect Microbiol. 2025 ;15 1691360

Modified Zhujing pill regulates RPE cholesterol metabolism and gut microbiota in an age-related macular degeneration mouse model.

Shuibin Cen, Shiqin Xie, Khalid S Ibrahim, Michal R Baran, Xing Li, James Reilly, Zhoujin Tan, Zhiming He, Xinhua Shu.

Background: Age-related macular degeneration (AMD) is a common retinal disorder, causing blindness in aged individuals. One of the traditional Chinese medicines, modified Zhujing pill (MZP), has been widely used to treat various ocular disorders, including AMD; however, its protective mechanisms remain elusive. In this study, we explored the functional role of MZP in high-fat-diet-fed mice, a commonly used model for AMD.
Methods: Compounds of MZP water extract were identified by high-performance liquid chromatography (HPLC)/mass spectrometry (MS)/MS. The mice were divided into three groups: group 1 mice fed with control diet (CD), group 2 mice fed with high-fat diet (HFD), and group 3 mice fed with HFD for 12 weeks; groups 1 and 2 were then treated with physiological saline, while group 3 was treated with MZP for 4 weeks. The cholesterol level and expression of cholesterol homeostasis-associated genes, antioxidant genes, and proinflammatory cytokines in mouse tissues were measured using biochemical approaches. Mouse cecum microbiota compositions and metabolic functions were analyzed using 16rRNA sequencing and bioinformatics approach.
Results: HFD-fed mice had high levels of cholesterol in the retinal pigment epithelial (RPE) cells, liver, and serum, a decreased expression of cholesterol homeostasis-associated genes and antioxidant genes in the RPE and liver, and an increased expression of proinflammatory cytokines. MZP treatment counteracted HFD-induced pathologic effects. Additionally, HFD altered cecum bacterial compositions and diversities associated with individual metabolic pathways. These metabolic pathways are involved in the biosynthesis of bacterial metabolites, mitochondrial function, oxidative stress, and inflammation. MZP reversed most of the changes back to control characteristics.
Conclusion: We postulate that the beneficial effects of MZP against AMD are possibly related to lowering the cholesterol level, suppressing oxidative stress and inflammation, and modulating gut microbiota and associated functions.

Keywords: age related macular degeneration; cholesterol; gut microbiota; inflammation; modified Zhujing pill; oxidative stress

DOI: https://doi.org/10.3389/fcimb.2025.1691360