bims-mideyd Biomed News
on Mitochondrial dysfunction in eye diseases
Issue of 2023–02–26
six papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington
  1. Effect of palmitoylethanolamide on degeneration of a human-derived retinal pigment epithelial cell induced by all-trans retinal.
  2. TRAP1 Is Expressed in Human Retinal Pigment Epithelial Cells and Is Required to Maintain their Energetic Status.
  3. The Anti-Aging Hormone Klotho Promotes Retinal Pigment Epithelium Cell Viability and Metabolism by Activating the AMPK/PGC-1α Pathway.
  4. Changes in the Expression Profile of Pyroptosis-Related Genes in Senescent Retinal Pigment Epithelial Cells after Lutein Treatment.
  5. Metabolic Imaging and Molecular Biology Reveal the Interplay between Lipid Metabolism and DHA-Induced Modulation of Redox Homeostasis in RPE Cells.
  6. Protein-Mediated Carotenoid Delivery Suppresses the Photoinducible Oxidation of Lipofuscin in Retinal Pigment Epithelial Cells.
  1. Int J Ophthalmol. 2023 ;16(2): 191-200
    Effect of palmitoylethanolamide on degeneration of a human-derived retinal pigment epithelial cell induced by all-trans retinal.
    Yun Han, Kun-Huan Yang, Dan-Xue He, Chao-Feng Yu, Lei Tao, Chun-Yan Liao, Bin-Xiang Cai, Zu-Guo Liu, Yan Qiu, Ya-Lin Wu.
       AIM: To study the effect of palmitoylethanolamide (PEA) on apoptosis of retinal pigment epithelial (RPE) cells induced by all-trans retinal (atRAL) and to explore the possible molecular mechanism.
    METHODS: CellTiter 96® Aqueous One Solution Cell Proliferation Assay (MTS) was used to detect the effect of PEA on human-derived retinal epithelial cells (ARPE-19) viability induced by atRAL. A Leica DMi8 inverted microscope was used to observe cell morphology. Reactive oxygen species (ROS) production was evaluated with 2',7'-dichlorodihydrof-luorescein diacetate (H2DCFDA) staining and fluorescence microscopy. Expression of c-Jun N-terminal kinase (JNK), phosphorylated JNK (p-JNK), c-Jun, phosphorylated c-Jun (p-c-Jun), Bak, cleaved caspase-3, C/EBP homologous protein (CHOP), and binding (Bip) protein levels were tested by Western blot. Abca4 -/- Rdh8 -/- mice, mouse models of atRAL clearance defects which displays some symbolic characteristics of dry age-related macular degeneration (AMD) and Stargardt disease (STGD1). In the animal models, PEA was injected intraperitoneally. The full-field electroretinogram was used to detect visual function under scotopic conditions traced from mice. Optical coherence tomography showed reconstitution or thickening of the retinal pigment epithelium layer. Effect of PEA on fundus injury induced by light in Abca4-/-Rdh8-/- mice was observed by fundus photography.
    RESULTS: PEA ameliorated ARPE-19 cells apoptosis and inhibited ROS (including mitochondrial ROS) production induced by atRAL. PEA improved the retinal functional, prohibited both RPE and photoreceptor from death, ameliorates light-induced fundus impairment in Abca4 -/- Rdh8 -/- mice. In vitro and in vivo, PEA inhibited JNK, p-JNK, c-Jun, p-c-Jun, Bak, cleaved caspase-3, CHOP, and Bip protein levels induced by all-trans retinal in ARPE-19 cells.
    CONCLUSION: PEA has effect on treating RPE cells apoptosis in retinopathy caused by atRAL accumulation. PEA is a potential treatment strategy for dry AMD and STGD1. The molecular mechanism is affecting the ROS-JNK-CHOP signaling pathway partly.
    Keywords:  ARPE-19; all-trans retinal; apoptosis; fundus; palmitoethanolamide
    DOI:  https://doi.org/10.18240/ijo.2023.02.04
  2. Antioxidants (Basel). 2023 Feb 04. pii: 381. [Epub ahead of print]12(2):
    TRAP1 Is Expressed in Human Retinal Pigment Epithelial Cells and Is Required to Maintain their Energetic Status.
    Inês Ramos Rego, Daniela Silvério, Maria Isabel Eufrásio, Sandra Sofia Pinhanços, Bruna Lopes da Costa, José Teixeira, Hugo Fernandes, Yang Kong, Yao Li, Stephen H Tsang, Paulo J Oliveira, Rosa Fernandes, Peter M J Quinn, Paulo Fernando Santos, António Francisco Ambrósio, Celso Henrique Alves.
      Age-related macular degeneration (AMD) is the leading cause of severe vision loss and blindness in elderly people worldwide. The damage to the retinal pigment epithelium (RPE) triggered by oxidative stress plays a central role in the onset and progression of AMD and results from the excessive accumulation of reactive oxygen species (ROS) produced mainly by mitochondria. Tumor necrosis factor receptor-associated protein 1 (TRAP1) is a mitochondrial molecular chaperone that contributes to the maintenance of mitochondrial integrity by decreasing the production and accumulation of ROS. The present study aimed to evaluate the presence and the role of TRAP1 in the RPE. Here, we report that TRAP1 is expressed in human adult retinal pigment epithelial cells and is located mainly in the mitochondria. Exposure of RPE cells to hydrogen peroxide decreases the levels of TRAP1. Furthermore, TRAP1 silencing increases intracellular ROS production and decreases mitochondrial respiratory capacity without affecting cell proliferation. Together, these findings offer novel insights into TRAP1 functions in RPE cells, opening possibilities to develop new treatment options for AMD.
    Keywords:  age-related macular degeneration (AMD); mitochondria; oxidative stress; retinal pigment epithelium (RPE); tumor necrosis factor receptor-associated protein 1 (TRAP1)
    DOI:  https://doi.org/10.3390/antiox12020381
  3. Antioxidants (Basel). 2023 Feb 05. pii: 385. [Epub ahead of print]12(2):
    The Anti-Aging Hormone Klotho Promotes Retinal Pigment Epithelium Cell Viability and Metabolism by Activating the AMPK/PGC-1α Pathway.
    Shuyan Zhou, Jacob Hum, Kaan Taskintuna, Stephanie Olaya, Jeremy Steinman, Junfeng Ma, Nady Golestaneh.
      Initially discovered by Makuto Kuro-o in 1997, Klotho is a putative aging-suppressor gene when overexpressed and accelerates aging when deleted in mice. Previously, we showed that α-Klotho regulates retinal pigment epithelium (RPE) functions and protects against oxidative stress. However, the mechanisms by which Klotho influences RPE and retinal homeostasis remain elusive. Here, by performing a series of in vitro and in vivo experiments, we demonstrate that Klotho regulates cell viability under oxidative stress, mitochondrial gene expression and activity by inducing the phosphorylation of AMPK and p38MAPK, which in turn phosphorylate and activate CREB and ATF2, respectively, triggering PGC-1α transcription. The inhibition of Klotho in human RPE cells using CRISPR-Cas9 gene editing confirmed that a lack of Klotho negatively affects RPE functions, including mitochondrial activity and cell viability. Proteomic analyses showed that myelin sheath and mitochondrial-related proteins are downregulated in the RPE/retina of Kl-/- compared to WT mice, further supporting our biochemical observations. We conclude that Klotho acts upstream of the AMPK/PGC-1α pathway and regulates RPE/retinal resistance to oxidative stress, mitochondrial function, and gene and protein expressions. Thus, KL decline during aging could negatively impact retinal health, inducing age-related retinal degeneration.
    Keywords:  AMD; AMPK; Klotho; PGC-1a; aging; retina; retinal pigment epithelium
    DOI:  https://doi.org/10.3390/antiox12020385
  4. Curr Issues Mol Biol. 2023 Feb 09. 45(2): 1500-1518
    Changes in the Expression Profile of Pyroptosis-Related Genes in Senescent Retinal Pigment Epithelial Cells after Lutein Treatment.
    Barbara Strzalka-Mrozik, Marcel Madej, Natalia Kurowska, Celina Kruszniewska-Rajs, Magdalena Kimsa-Dudek, Jolanta Adamska, Joanna Magdalena Gola.
      Retinal pigment epithelium (RPE) is a specialized structure essential for proper vision, which is constantly exposed to oxidative damage. With aging, this damage accumulates within the RPE cells, causing various diseases, including age-related macular degeneration (AMD). Numerous antioxidant substances are used to prevent this process in humans, including lutein. This study aims to determine the differences in the expression patterns of pyroptosis genes in senescent human retinal pigment epithelial cell line ARPE-19 exposed to lutein. Changes in the expression of pyroptosis-related genes were assessed by oligonucleotide microarrays, and the results were validated by real-time RT-qPCR. The microarray analysis showed seven transcripts were differentially expressed both in the H2O2-treated cells versus the controls and in the lutein/H2O2-treated cells compared to the H2O2-treated cells (FC > 2.0). Depending on the used lutein, H2O2, or co-treatment of ARPE-19 cells, statistically significant differences in the expression of TXNIP, CXCL8, BAX, and CASP1 genes were confirmed by the RT-qPCR (p < 0.05). A STRING database analysis showed that the proteins encoded by the analyzed genes form a strong interaction network (p < 0.001). These data indicate that lutein modulates the expression level of pyroptosis-related genes, which may be useful for the development of new methods preventing pyroptosis pathway activation in the future.
    Keywords:  expression; genes; lutein; oligonucleotide microarray; oxidative stress; pyroptosis; real-time RT-qPCR; senescent retinal pigment epithelial cells
    DOI:  https://doi.org/10.3390/cimb45020097
  5. Antioxidants (Basel). 2023 Jan 31. pii: 339. [Epub ahead of print]12(2):
    Metabolic Imaging and Molecular Biology Reveal the Interplay between Lipid Metabolism and DHA-Induced Modulation of Redox Homeostasis in RPE Cells.
    Giada Bianchetti, Maria Elisabetta Clementi, Beatrice Sampaolese, Cassandra Serantoni, Alessio Abeltino, Marco De Spirito, Shlomo Sasson, Giuseppe Maulucci.
      Diabetes-induced oxidative stress induces the development of vascular complications, which are significant causes of morbidity and mortality in diabetic patients. Among these, diabetic retinopathy (DR) is often caused by functional changes in the blood-retinal barrier (BRB) due to harmful oxidative stress events in lipids, proteins, and DNA. Docosahexaenoic acid (DHA) has a potential therapeutic effect against hyperglycemia-induced oxidative damage and apoptotic pathways in the main constituents of BRB, retinal pigment epithelium cells (ARPE-19). Effective antioxidant response elicited by DHA is driven by the activation of the Nrf2/Nqo1 signaling cascade, which leads to the formation of NADH, a reductive agent found in the cytoplasm. Nrf2 also induces the expression of genes encoding enzymes involved in lipid metabolism. This study, therefore, aims at investigating the modulation of lipid metabolism induced by high-glucose (HG) on ARPE-19 cells through the integration of metabolic imaging and molecular biology to provide a comprehensive functional and molecular characterization of the mechanisms activated in the disease, as well the therapeutic role of DHA. This study shows that HG augments RPE metabolic processes by enhancing lipid metabolism, from fatty acid uptake and turnover to lipid biosynthesis and β-oxidation. DHA exerts its beneficial effect by ameliorating lipid metabolism and reducing the increased ROS production under HG conditions. This investigation may provide novel insight for formulating novel treatments for DR by targeting lipid metabolism pathways.
    Keywords:  blood-retinal barrier; diabetic retinopathy; docosahexaenoic acid (DHA); human retinal pigment epithelium cells (ARPE-19); lipid metabolism; metabolic imaging; oxidative stress; retinal diseases; β-oxidation
    DOI:  https://doi.org/10.3390/antiox12020339
  6. Antioxidants (Basel). 2023 Feb 08. pii: 413. [Epub ahead of print]12(2):
    Protein-Mediated Carotenoid Delivery Suppresses the Photoinducible Oxidation of Lipofuscin in Retinal Pigment Epithelial Cells.
    Alexey N Semenov, Eugene G Maksimov, Anastasia M Moysenovich, Marina A Yakovleva, Georgy V Tsoraev, Alla A Ramonova, Evgeny A Shirshin, Nikolai N Sluchanko, Tatiana B Feldman, Andrew B Rubin, Mikhail P Kirpichnikov, Mikhail A Ostrovsky.
      Lipofuscin of retinal pigment epithelium (RPE) cells is a complex heterogeneous system of chromophores which accumulates as granules during the cell's lifespan. Lipofuscin serves as a source of various cytotoxic effects linked with oxidative stress. Several age-related eye diseases such as macular degeneration of the retina, as well as some severe inherited eye pathologies, are accompanied by a significant increase in lipofuscin granule concentration. The accumulation of carotenoids in the RPE could provide an effective antioxidant protection against lipofuscin cytotoxic manifestations. Given the highly lipophilic nature of carotenoids, their targeted delivery to the vulnerable tissues can potentially be assisted by special proteins. In this study, we demonstrate how protein-mediated delivery of zeaxanthin using water-soluble Bombyx mori carotenoid-binding protein (BmCBP-ZEA) suppresses the photoinducible oxidative stress in RPE cells caused by irradiation of lipofuscin with intense white light. We implemented fluorescence lifetime imaging of the RPE cell culture ARPE-19 fed with lipofuscin granules and then irradiated by white light with and without the addition of BmCBP-ZEA. We demonstrate that after irradiation the mean fluorescence lifetime of lipofuscin significantly increases, while the presence of BmCBP-ZEA at 200 nM concentration suppresses the increase in the average lifetime of lipofuscin fluorescence, indicating an approx. 35% inhibition of the oxidative stress. This phenomenon serves as indirect yet important evidence of the efficiency of the protein-mediated carotenoid delivery into pigment epithelium cells.
    Keywords:  FLIM; bisretinoid fluorophores; bisretinoid oxidation and degradation products; carotenoid-binding protein; lipofuscin; retinal pigment epithelium; zeaxanthin delivery
    DOI:  https://doi.org/10.3390/antiox12020413
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