bims-mideyd 2023-01-15 papers

bims-mideyd

Biomed News

on Mitochondrial dysfunction in eye diseases

Issue of 2023–01–15
seven papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

NLRX1 increases human retinal pigment epithelial autophagy and reduces H2O2-induced oxidative stress and inflammation by suppressing FUNDC1 phosphorylation and NLRP3 activation.
Retinal Pigment Epithelium Transplantation: Past, Present, and Future.
Oxidative Stress and Lipid Accumulation Augments Cell Death in LDLR-Deficient RPE Cells and Ldlr-/- Mice.
ER stress-associated transcription factor CREB3 is essential for normal Ca2+, ATP, and ROS homeostasis.
Mitochondria-associated endoplasmic reticulum membranes dysfunction contributes to PARP-1-dependent cell death under oxidative stress in retinal precursor cells.
MiR-302a Regenerates Human Corneal Endothelial Cells against IFN-γ-Induced Cell Death.
Mitochondrial ROS induced by ML385, an Nrf2 inhibitor aggravates the ferroptosis induced by RSL3 in human lung epithelial BEAS-2B cells.

Allergol Immunopathol (Madr). 2023 ;51(1): 177-186

NLRX1 increases human retinal pigment epithelial autophagy and reduces H2O2-induced oxidative stress and inflammation by suppressing FUNDC1 phosphorylation and NLRP3 activation.

Qian Wang, Fengying He, Liping Wu.

   BACKGROUND: Age-related macular degeneration (AMD) is a leading cause of impaired vision as well as some earlier effects, such as reading and face recognition. Oxidative damage and inflammation of retinal pigment epithelial (RPE) cells are major causes of AMD. Additionally, autophagy in RPE cells can lead to cellular homeostasis under oxidative stress. Nucleotide-binding oligomerization domain (NOD)-like receptor X1 (NLRX1) is a mysterious modulator of the immune system function which inhibits inflammatory response, attenuates reactive oxygen species (ROS) production, and regulates autophagy. This study attempted to explore the role of NLRX1 in oxidative stress, inflammation, and autophagy in AMD.
METHODS: An in vitro model of AMD was built in human retinal pigment epithelial cell line 19 (ARPE-19) treated with H2O2. The cell viability, NLRX1 expressions, levels of superoxide dismutase (SOD), glutathione (GHS), and ROS, concentrations of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, and monocyte chemoattractant protein-1 (MCP-1), expressions of NLRX1, p62, LC3-II/LC3-I, FUNDC1, and NOD-like receptor protein 3 (NLRP3) inflammasome were expounded by cell counting kit-8, colorimetric, enzyme-linked immunosorbent serologic assay (ELISA), and Western blot assay.
RESULTS: H2O2 treatment notably reduced the relative protein expression of NLRX1. Meanwhile, H2O2 incubation decreased cell viability, diminished SOD and GSH concentrations, accompanied with the increased level of ROS, enhanced IL-1β, TNF-α, IL-6, and MCP-1 concentrations, and aggrandized the relative protein expression of p62 with reduced LC3-II/LC3-I ratio. Moreover, these results were further promoted with knockdown of NLRX1 and reversed with overexpression. Mechanically, silencing of NLRX1 further observably enhanced the relative levels of -phosphorylated FUNDC1/FUNDC1, and NLRP3 inflammasome-related proteins, while overexpression of NLRX1 exhibited inverse results in the H2O2-induced ARPE-19 cells.
CONCLUSION: NLRX1 suppressed H2O2-induced oxidative stress and inflammation, and facilitated autophagy by suppressing FUNDC1 phosphorylation and NLRP3 activation in ARPE-19 cells.

Keywords:  FUNDC1; Inflammation; NLRP3 inflammasome; NLRX1; age-related macular degeneration; autophagy; oxidative stress

DOI:  https://doi.org/10.15586/aei.v51i1.766
J Ophthalmic Vis Res. 2022 Oct-Dec;17(4):17(4): 574-580

Retinal Pigment Epithelium Transplantation: Past, Present, and Future.

Ayyad Zartasht Khan, Tor Paaske Utheim, Jon Roger Eidet.

  Retinal pigment epithelium (RPE) is a monolayer of cells situated between photoreceptors and the underlying choroid. It is essential for normal retinal function. Damaged RPE is associated with diseases such as age-related macular degeneration, Stargardt's macular dystrophy, and retinitis pigmentosa. RPE cells can easily be visualized in vivo, sustainable in vitro, and differentiated from stem cells with a relatively straightforward protocol. Due to these properties and the clinical significance of this epithelium in various retinal diseases, RPE transplantation as a treatment modality has gained considerable interest in the last decade. This paper presents the main techniques for RPE transplantation and discusses recent clinically relevant publications.

Keywords:   Regenerative Medicine; Retinal Pigment Epithelium Transplantation; Tissue Engineering.; Vitreoretinal Surgery; Retinal Pigment Epithelium

DOI:  https://doi.org/10.18502/jovr.v17i4.12325
Cells. 2022 Dec 22. pii: 43. [Epub ahead of print]12(1):

Oxidative Stress and Lipid Accumulation Augments Cell Death in LDLR-Deficient RPE Cells and Ldlr-/- Mice.

Parameswaran Gangadharan Sreekumar, Feng Su, Christine Spee, Eduardo Araujo, Steven Nusinowitz, Srinivasa T Reddy, Ram Kannan.

  Lipid peroxidation from oxidative stress is considered a major contributor to age-related macular degeneration (AMD). The retina is abundant with circulating low-density lipoproteins (LDL), which are taken up by LDL receptor (LDLR) in the RPE and Müller cells. The purpose of this study is to investigate the role of LDLR in the NaIO3-induced model of dry AMD. Confluent primary human RPE (hRPE) and LDLR-silenced ARPE-19 cells were stressed with 150 µM tert-butyl hydroperoxide (tBH) and caspase 3/7 activation was determined. WT and Ldlr-/- mice were administered NaIO3 (20 mg/kg) intravenously. On day 7, fundus imaging, OCT, ERG, and retinal thickness were measured. Histology, TUNEL, cleaved caspase 3 and lipid accumulation were assessed. Treatment of hRPE with tBH markedly decreased LDLR expression. Caspase 3/7 activation was significantly increased in LDLR-silenced ARPE-19 cells treated with tBH. In Ldlr-/- mice, NaIO3 administration resulted in significant (a) retinal thinning, (b) compromised photoreceptor function, (c) increased percentage of cleaved caspase 3 positive and apoptotic cells, and (d) increased lipid droplet accumulation in the RPE, Bruch membrane, choroid, and sclera, compared to WT mice. Our findings imply that LDLR loss leads to lipid accumulation and impaired retinal function, which may contribute to the development of AMD.

Keywords:  geographic atrophy; inflammation; low-density lipoprotein receptor; oxidative stress; retinal degeneration; retinal function; retinal pigment epithelium

DOI:  https://doi.org/10.3390/cells12010043
Mitochondrion. 2023 Jan 07. pii: S1567-7249(23)00001-6. [Epub ahead of print]

ER stress-associated transcription factor CREB3 is essential for normal Ca2+, ATP, and ROS homeostasis.

Brandon S Smith, Tristen Hewitt, Marica Bakovic, Ray Lu.

  In mammalian cells, mitochondrial respiration produces reactive oxygen species (ROS) such as superoxide (O2-), which is then converted by the SOD1 enzyme into hydrogen peroxide (H2O2), the predominant form of cytosolic ROS. ROS at high levels can be toxic, but below this threshold are important for physiological processes acting as a second messenger similar to Ca2+. Mitochondrial Ca2+ influx from the ER increases ATP and ROS production, while ATP and ROS can regulate Ca2+ homeostasis, leading to an intricate interplay between Ca2+, ROS, and ATP synthesis. The Unfolded Protein Response (UPR) proteins ATF6α and XBP1 contribute to protection from oxidative stress through upregulation of Sod1 and Catalase genes. Here, UPR-associated protein CREB3 is shown to play a role in balancing Ca2+, ROS, and ATP homeostasis. Creb3-deficient mouse embryonic fibroblast cells (MEF-/-) were susceptible to H2O2-induced oxidative stress while having a functioning antioxidant gene expression response compared to MEF+/+. MEF-/- cells also contained elevated basal cytosolic ROS levels, which was attributed to drastically increased basal mitochondrial respiration and spare respiratory capacity relative to MEF+/+. MEF-/- cells also showed an increase in endoplasmic reticulum Ca2+ release and mitochondrial Ca2+ levels hinting at a potential cause for MEF-/- cell mitochondrial dysfunction. These results suggest that CREB3 is essential for maintaining proper Ca2+, ATP, and ROS homeostasis in mammalian cells.

Keywords:  CREB3; Calcium; Cellular Respiration; Homeostasis; Mitochondria; Oxidative Stress; Reactive Oxygen Species

DOI:  https://doi.org/10.1016/j.mito.2023.01.001
J Biochem Mol Toxicol. 2023 Jan 13. e23303

Mitochondria-associated endoplasmic reticulum membranes dysfunction contributes to PARP-1-dependent cell death under oxidative stress in retinal precursor cells.

Yuting Yang, Jihong Wu, Wei Lu, Yiqin Dai, Youjia Zhang, Xinghuai Sun.

  Persistent poly (ADP-ribose) polymerase 1 (PARP-1) activation has proven detrimental and can lead to PARP-1-dependent cell death. Mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) serve as essential hubs for many biological pathways, such as autophagy and mitochondria fission and fusion. This study aimed to alleviate the effects of hydrogen peroxide (H2 O2 )-induced persistent PARP-1 activation and MAM dysregulation by the usage of a PARP-1 inhibitor. Results showed that receptor-interacting protein kinase (RIPK) 1 inhibitor (necrostatin-1) and PARP-1 inhibitor (olaparib) protected retinal precursor cells from H2 O2 -induced death, while a pan-caspase inhibitor (Z-VAD-FMK) failed to protect R28 cells. Olaparib also alleviated H2 O2 -induced MAM dysregulation, as evidenced by decreased VDAC1/ITPR3 interactions and reduced mitochondrial membrane potential collapse. Additionally, olaparib also inhibited H2 O2 -induced autophagy. Inhibiting autophagic flux increased MAM signaling under both normal and oxidative conditions. Furthermore, H2 O2 treatment caused a reduction in the protein level of mitofusin-2 (MFN2) in a dose- and time-dependent manner. Mfn2 knockdown was found to further magnify MAM dysregulation and mitochondrial dysfunction under normal and oxidative conditions. Mfn2 overexpression surprisingly enhanced H2 O2 -induced MAM signaling and failed to rescue H2 O2 -induced mitochondrial dysfunction. These results indicate that MAMs probably serve as a membrane source for oxidative stress-associated autophagy. MAM dysregulation also contributed to H2 O2 -induced PARP-1-dependent cell death. However, more studies are required to decipher the link between the modulation of Mfn2 expression, changes in MAM integrity, and alterations in mitochondrial performances.

Keywords:  MAM; MFN2; Olaparib; PARP-1; hydrogen peroxide

DOI:  https://doi.org/10.1002/jbt.23303
Cells. 2022 Dec 22. pii: 36. [Epub ahead of print]12(1):

MiR-302a Regenerates Human Corneal Endothelial Cells against IFN-γ-Induced Cell Death.

Se-Hie Park, Jin-Sun Hwang, Sun-Hee Oh, Young-Joo Shin.

  Damage to human corneal endothelial cells (hCECs) leads to bullous keratopathy because these cells cannot be regenerated in vivo. In this study, we investigated the protective role of microRNA (miR)-302a against interferon-γ (IFN-γ)-induced senescence and cell death of hCECs. Cultured hCECs were transfected with miR-302a and treated with IFN-γ (20 ng/mL) to evaluate the protective effect of miR-302a on IFN-γ-induced cell death. Senescence was evaluated by the senescence-associated β-galactosidase (SA-β-gal) assay, and the secretion of senescence-associated secretory phenotype (SASP) factors was analyzed. Mitochondrial function and endoplasmic reticulum (ER) stress were assessed. We revealed that miR-302a enhanced the cell viability and proliferation of hCECs and that IFN-γ increased the cell size, the number of SA-β-gal-positive cells, and SASP factors, and arrested the cell cycle, which was eliminated by miR-302a. miR-302a ameliorated mitochondrial oxidative stress and ER stress levels which were induced by IFN-γ. IFN-γ decreased the mitochondrial membrane potential and promoted autophagy, which was eliminated by miR-302a. The in vivo study showed that regeneration of rat CECs was promoted in the miR-302a group by inhibiting IFN-γ and enhancing mitochondrial function. In conclusion, miR-302a eliminated IFN-γ-induced senescence and cellular damage by regulating the oxidative and ER stress, and promoting the proliferation of CECs. Therefore, miR-302a may be a therapeutic option to protect hCECs against IFN-γ-induced stress.

Keywords:  human corneal endothelial cells; interferon-γ; miR-302a; senescence

DOI:  https://doi.org/10.3390/cells12010036
Hum Exp Toxicol. 2023 Jan-Dec;42:42 9603271221149663

Mitochondrial ROS induced by ML385, an Nrf2 inhibitor aggravates the ferroptosis induced by RSL3 in human lung epithelial BEAS-2B cells.

Indra Putra Taufani, Jiro Hasegawa Situmorang, Rifki Febriansah, Sri Tasminatun, Sunarno Sunarno, Liang-Yo Yang, Yi-Ting Chiang, Chih-Yang Huang.

  Ferroptosis is a new type of cell death marked by iron and lipid ROS accumulation. GPX4 is one of the glutathione peroxidases known to regulate ferroptosis tightly. On the other hand, Nrf2 also plays a vital role in ferroptosis as it targets genes related to oxidant defense. Herein, we employed beas-2 human epithelial cells treated with a low concentration of RSL3 to induce ferroptosis. To study the protective role of Nrf2, we used ML385 as its specific inhibitor. A combination of ML385 and a low concentration of RSL3 synergistically induced more toxicity to RSL3. Furthermore, we found that mitochondrial ROS is elevated in ML385 and RSL3 combination group. In addition, Mito TEMPOL application successfully prevents the upregulation of mitochondrial ROS, lipid ROS, reduces the toxicity of RSL3, restores the antioxidant capacity of the cells, and mitochondrial functions reflected by mitochondrial membrane potential and mitochondrial oxidative phosphorylation system (OXPHOS) expression. Altogether, our study demonstrated that Nrf2 inhibition by ML385 induces more toxicity when combined with RSL3 through the elevation of mitochondrial ROS and disruption of mitochondrial function.

Keywords:  Ferroptosis; GPX4; Mito TEMPOL; Nrf2 inhibition; OXPHOS; RSL3; mitochondrial ROS

DOI:  https://doi.org/10.1177/09603271221149663