scholarly journals Tunicamycin-Induced ER Stress is Accompanied with Oxidative Stress via Abrogation of Sulfur Amino Acids Metabolism in the Liver

2018 ◽  
Vol 19 (12) ◽  
pp. 4114 ◽  
Author(s):  
Sou Kim ◽  
Do-young Kwon ◽  
Jae-Hwan Kwak ◽  
Seunghyun Lee ◽  
Yun-Hee Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Amino Acids ◽  
Er Stress ◽  
Hepg2 Cells ◽  
Liver Lipid ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Sulfur Amino Acids ◽  
Alcoholic Fatty Liver ◽  
Endogenous Antioxidant

Endoplasmic reticulum (ER) stress is involved in non-alcoholic fatty liver disease (NAFLD), but the relationship between oxidative stress, another well-known risk factor of NAFLD, and ER stress has yet to be elucidated. In this study, we treated mice with tunicamycin (TM) (2 mg/kg body weight) for 48 h to induce ER stress in the liver and examined the metabolic pathway that synthesizes the endogenous antioxidant, glutathione (GSH). Tunicamycin (TM) treatment significantly increased mRNA levels of CHOP and GRP78, and induced lipid accumulation in the liver. Lipid peroxidation in the liver tissue also increased from TM treatment (CON vs. TM; 3.0 ± 1.8 vs. 11.1 ± 0.8 nmol MDA/g liver, p < 0.001), which reflects an imbalance between the generation of reactive substances and antioxidant capacity. To examine the involvement of GSH synthetic pathway, we determined the metabolomic changes of sulfur amino acids in the liver. TM significantly decreased hepatic S-adenosylmethionine concentration in the methionine cycle. The levels of cysteine in the liver were increased, while taurine concentration was maintained and GSH levels profoundly decreased (CON vs. TM; 8.7 ± 1.5 vs. 5.4 ± 0.9 µmol GSH/g liver, p < 0.001). These results suggest that abnormal cysteine metabolism by TM treatment resulted in a decrease in GSH, followed by an increase in oxidative stress in the liver. In HepG2 cells, decreased GSH levels were examined by TM treatment in a dose dependent manner. Furthermore, pretreatment with TM in HepG2 cells potentiated oxidative cell death, by exacerbating the effects of tert-butyl hydroperoxide. In conclusion, TM-induced ER stress was accompanied by oxidative stress by reducing the GSH synthesis, which made the liver more susceptible to oxidative stress.

Toxicity of Zirconia oxide Nanoparticles: Liver Biodistribution and Liver Damages

2020 ◽  
Author(s):  
Ting Sun ◽  
Lingling Ou ◽  
Xiaozhen Zhan ◽  
Wenxin Zhao ◽  
Rui Huang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signaling Pathway ◽  
Hepg2 Cells ◽  
Large Scale ◽  
Inflammatory Responses ◽  
Scale Production ◽  
Dependent Manner ◽  
Alcoholic Fatty Liver ◽  
Toxicological Effects

Abstract Background: Zirconia nanoparticles (ZrO2-NPs) have been increasingly used in industrial, biomedical and dental materials. However, the scientific basis for the toxicological effects of ZrO2-NPs is poorly elucidated, and the understanding of the underlying mechanism is still limited. Results: The hepatic biodistribution and toxicological effects of ZrO2-NPs after intravenous administration (20mg/kg bw) in vivo and the toxicological mechanism toward hepatocytes in vitro were investigated. The liver showed continuous ZrO2-NP accumulations liver over a 28-d period. Moreover, ZrO2-NPs induced oxidative stress and increased inflammatory responses and functional injury in the liver. Hepasteatosis and cell death were observed in histopathological and immunohistochemical studies. RNA-seq identified the main pathways involved in the metabolism, cellular process, and human diseases. The RT-qPCR analysis results showed that ZrO2-NP exposure caused the upregulation of P53, Foxo1, Gadd45g, P21, Caspase3, and PPARα and the downregulation of Igfbp2 and Akt in the liver in response to the ZrO2-NP treatment. Meanwhile, the results of the in vitro studies demonstrated that ZrO2-NPs exposure resulted in cytotoxicity in Hepg2 cells in a dose- and time-dependent manner. ZrO2-NPs were proven to induce oxidative stress, lipid accumulation, cell cycle arrest and cell apoptosis to Hepg2 cells. Western-blot analysis further proved the depression of Igfbp2, activation of Akt-mediated signaling pathway and P53-mediated signaling pathway for Hepg2 cells exposure to ZrO2-NPs. Conclusions: This study proves that ZrO2-NPs have negative impacts on the liver and exhibit potential risks for non-alcoholic fatty liver disease (NAFLD). There is potential concern over ZrO2-NPs' hepatoxicity in biomedical applications and occupational exposure through large-scale production.

scholarly journals Aqueous Extract of Pepino Leaves Ameliorates Palmitic Acid-Induced Hepatocellular Lipotoxicity via Inhibition of Endoplasmic Reticulum Stress and Apoptosis

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 903
Author(s):  
Jen-Ying Hsu ◽  
Hui-Hsuan Lin ◽  
Charng-Cherng Chyau ◽  
Zhi-Hong Wang ◽  
Jing-Hsien Chen
Keyword(s):  
Fatty Acid ◽  
Palmitic Acid ◽  
Er Stress ◽  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Target Genes ◽  
Liver Lipid ◽  
Antioxidant Response ◽  
Long Chain Fatty Acid ◽  
Nrf2 Expression

Saturated fatty acid is one of the important nutrients, but contributes to lipotoxicity in the liver, causing hepatic steatosis. Aqueous pepino leaf extract (AEPL) in the previous study revealed alleviated liver lipid accumulation in metabolic syndrome mice. The study aimed to investigate the mechanism of AEPL on saturated long-chain fatty acid-induced lipotoxicity in HepG2 cells. Moreover, the phytochemical composition of AEPL was identified in the present study. HepG2 cells treated with palmitic acid (PA) were used for exploring the effect of AEPL on lipid accumulation, apoptosis, ER stress, and antioxidant response. The chemical composition of AEPL was analyzed by HPLC-ESI-MS/MS. AEPL treatment reduced PA-induced ROS production and lipid accumulation. Further molecular results revealed that AEPL restored cytochrome c in mitochondria and decreased caspase 3 activity to cease apoptosis. In addition, AEPL in PA-stressed HepG2 cells significantly reduced the ER stress and suppressed SREBP-1 activation for decreasing lipogenesis. For defending PA-induced oxidative stress, AEPL promoted Nrf2 expression and its target genes, SOD1 and GPX3, expressions. The present study suggested that AEPL protected from PA-induced lipotoxicity through reducing ER stress, increasing antioxidant ability, and inhibiting apoptosis. The efficacy of AEPL on lipotoxicity was probably concerned with kaempferol and isorhamnetin derived compounds.

PERK mediates oxidative stress and adipogenesis in Graves’ orbitopathy pathogenesis

2021 ◽  
Author(s):  
JaeSang Ko ◽  
Ji-Young Kim ◽  
Min Kyung Chae ◽  
Eun Jig Lee ◽  
Jin Sook Yoon
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Er Stress ◽  
Adipogenic Differentiation ◽  
Ros Generation ◽  
Mrna Levels ◽  
Graves Orbitopathy ◽  
Orbital Fibroblasts

We examined endoplasmic reticulum (ER) stress-related gene expression in orbital tissues from patients with Graves’ orbitopathy (GO) and the effects of silencing protein kinase RNA-like endoplasmic reticulum kinase (PERK) in primary orbital fibroblast cultures to demonstrate the therapeutic potential of PERK-modulating agents in GO management. The expression of ER stress related genes in orbital tissue harvested from individuals with or without GO was studied using real-time polymerase chain reaction. The role of PERK in GO pathogenesis was examined through small-interfering RNA (siRNA)-mediated silencing in cultured primary orbital fibroblasts. Intracellular reactive oxygen species (ROS) levels induced in response to cigarette smoke extract (CSE) or hydrogen peroxide were measured using 5-(and 6)-carboxy-20,70-dichlorodihydrofluorescein diacetate staining and flow cytometry. Cells were stained with Oil Red O, and adipogenesis-related transcription factor expression was evaluated through western blotting after adipogenic differentiation. PERK, activating transcription factor 4 (ATF4), and CCAAT-enhancer-binding protein (C/EBP)-homologous protein(CHOP)mRNA levels were significantly higher in GO orbital tissues than in non-GO orbital tissues. PERK silencing inhibited CSE- or hydrogen peroxide-induced ROS generation. After adipogenic differentiation, GO orbital fibroblasts revealed decreased lipid droplets and downregulation of C/EBPα, C/EBPβ, and peroxisome proliferator-activator gamma (PPARγ) in PERK siRNA-transfected cells. The orbital tissues of patients with GO were exposed to chronic ER stress and subsequently exhibited enhanced unfolded protein response (especially through the PERK pathway). PERK silencing reduced oxidative stress and adipogenesis in GO orbital fibroblasts in vitro. Our results imply that PERK-modulating agents can potentially be used to manage GO.

scholarly journals Human Proximal Tubule Epithelial Cells (HK-2) as a Sensitive In Vitro System for Ochratoxin A Induced Oxidative Stress

Toxins ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 787
Author(s):  
Enrique García-Pérez ◽  
Dojin Ryu ◽  
Hwa-Young Kim ◽  
Hae Dun Kim ◽  
Hyun Jung Lee
Keyword(s):  
Oxidative Stress ◽  
Ochratoxin A ◽  
Cell Lines ◽  
Time Dependent ◽  
Mrna Levels ◽  
Dependent Manner ◽  
In Vitro System ◽  
Glutathione Peroxidase 1 ◽  
Glucose 6 Phosphate Dehydrogenase

Ochratoxin A (OTA) is a mycotoxin that is potentially carcinogenic to humans. Although its mechanism remains unclear, oxidative stress has been recognized as a plausible cause for the potent renal carcinogenicity observed in experimental animals. The effect of OTA on oxidative stress parameters in two cell lines of LLC-PK1 and HK-2 derived from the kidneys of pig and human, respectively, were investigated and compared. We found that the cytotoxicity of OTA on LLC-PK1 and HK-2 cells was dose- and time-dependent in both cell lines. Furthermore, increased intracellular reactive oxygen species (ROS) induced by OTA in both cell lines were observed in a time-dependent manner. Glutathione (GSH) was depleted by OTA at >48 h in HK-2 but not in LLC-PK1 cells. While the mRNA levels of glucose-6-phosphate dehydrogenase (G6PD) and glutathione peroxidase 1 (GPX1) in LLC-PK1 were down-regulated by 0.67- and 0.66-fold, respectively, those of catalase (CAT), glutathione reductase (GSR), and superoxide dismutase 1 (SOD) in HK-2 were up-regulated by 2.20-, 2.24-, and 2.75-fold, respectively, after 72 h exposure to OTA. Based on these results, we conclude that HK-2 cells are more sensitive to OTA-mediated toxicity than LLC-PK1, and OTA can cause a significant oxidative stress in HK-2 as indicated by changes in the parameter evaluated.

Effect of fluoride on PERK-Nrf2 signaling pathway in mouse ameloblasts

2019 ◽  
Vol 38 (7) ◽  
pp. 833-845
Author(s):  
X Zhou ◽  
Z Chen ◽  
W Zhong ◽  
R Yu ◽  
L He
Keyword(s):  
Oxidative Stress ◽  
Er Stress ◽  
Signaling Pathway ◽  
Nuclear Import ◽  
Target Genes ◽  
Dental Fluorosis ◽  
Related Factor ◽  
Dependent Manner ◽  
Nrf2 Signaling Pathway ◽  
Glutamylcysteine Synthetase

In the development of dental fluorosis, oxidative stress is considered as the key mechanism. Endoplasmic reticulum (ER) stress can induce oxidative stress and activate the important antioxidative factor nuclear factor erythroid 2-related factor 2 (Nrf2) in a PKR-like ER kinase (PERK)-dependent manner, but combining ER stress and oxidative stress, the role of PERK-Nrf2 signaling pathway involved in fluoride-regulated ameloblasts is not fully defined. Here, we studied the effect of fluoride on PERK-Nrf2 signaling pathway in mouse ameloblasts. We found that low-dose and continuous fluoride exposure increased binding immunoglobulin protein expression and activated PERK–activating transcription factor 4 signaling pathway. Meanwhile, the expression of Nrf2 and its target genes (glutamylcysteine synthetase and glutathione S-transferase-P1) enhanced following ER stress. Tunicamycin increased the expression of PERK, leading to Nrf2 nuclear import, and tauroursodeoxycholate suppressed Nrf2 activation through PERK during ER stress, indicating that PERK activation is required for Nrf2 nuclear entry. Furthermore, tert-butylhydroquinone triggered the overexpression of Nrf2 to reduce ER stress, but luteolin inhibited Nrf2 nuclear localization to elevate ER stress. In summary, this study proved that fluoride under certain dose can induce ER stress and promote Nrf2 nuclear import via PERK activation and suggested that antioxidation mechanism mediated by PERK-Nrf2 can alleviate fluoride-induced ER stress effectively.

Vinpocetine protects liver against ischemia–reperfusion injury

2013 ◽  
Vol 91 (12) ◽  
pp. 1064-1070 ◽  
Author(s):  
Hala Fahmy Zaki ◽  
Rania Mohsen Abdelsalam
Keyword(s):  
Oxidative Stress ◽  
Inflammatory Cytokines ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Liver Lipid ◽  
Cerebrovascular Disorders ◽  
Cellular Damage ◽  
Dependent Manner ◽  
Oxidative Stress Biomarkers ◽  
Serum Transaminases

Hepatic ischemia–reperfusion (IR) injury is a clinical problem that leads to cellular damage and organ dysfunction mediated mainly via production of reactive oxygen species and inflammatory cytokines. Vinpocetine has long been used in cerebrovascular disorders. This study aimed to explore the protective effect of vinpocetine in IR injury to the liver. Ischemia was induced in rats by clamping the common hepatic artery and portal vein for 30 min followed by 30 min of reperfusion. Serum transaminases and liver lactate dehydrogenase (LDH) activities, liver inflammatory cytokines, oxidative stress biomarkers, and liver histopathology were assessed. IR resulted in marked histopathology changes in liver tissues coupled with elevations in serum transaminases and liver LDH activities. IR also increased the production of liver lipid peroxides, nitric oxide, and inflammatory cytokines interleukin-1β and interleukin-6, in parallel with a reduction in reduced glutathione and interleukin-10 in the liver. Pretreatment with vinpocetine protected against liver IR-induced injury, in a dose-dependent manner, as evidenced by the attenuation of oxidative stress as well as inflammatory and liver injury biomarkers. The effects of vinpocetine were comparable with that of curcumin, a natural antioxidant, and could be attributed to its antioxidant and anti-inflammatory properties.

scholarly journals An Antioxidant Phytotherapy to Rescue Neuronal Oxidative Stress

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Zhihong Lin ◽  
Danni Zhu ◽  
Yongqing Yan ◽  
Boyang Yu ◽  
Qiujuan Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Aqueous Extract ◽  
Ischemia Reperfusion ◽  
Brain Infarction ◽  
Reaction System ◽  
Artery Occlusion ◽  
Dependent Manner ◽  
Endogenous Antioxidant

Oxidative stress is involved in the pathogenesis of ischemic neuronal injury. A Chinese herbal formula composed ofPoria cocos(Chinese name:Fu Ling),Atractylodes macrocephala(Chinese name:Bai Zhu) andAngelica sinensis(Chinese names:Danggui, Dong quai, Donggui; Korean name:Danggwi) (FBD), has been proved to be beneficial in the treatment of cerebral ischemia/reperfusion (I/R).This study was carried out to evaluate the protective effect of FBD against neuronal oxidative stressin vivoandin vitro. Rat I/R were established by middle cerebral artery occlusion (MCAO) for 1 h, followed by 24 h reperfusion. MCAO led to significant depletion in superoxide dismutase and glutathione and rise in lipid peroxidation (LPO) and nitric oxide in brain. The neurological deficit and brain infarction were also significantly elevated by MCAO as compared with sham-operated group. All the brain oxidative stress and damage were significantly attenuated by 7 days pretreatment with the aqueous extract of FBD (250 mg kg−1, p.o.). Moreover, cerebrospinal fluid sampled from FBD-pretreated rats protected PC12 cells against oxidative insult induced by 0.2 mM hydrogen peroxide, in a concentration and time-dependent manner (IC5010.6%, ET501.2 h). However, aqueous extract of FBD just slightly scavenged superoxide anion radical generated in xanthine–xanthine oxidase system (IC502.4 mg ml−1) and hydroxyl radical generated in Fenton reaction system (IC503.6 mg ml−1). In conclusion, FBD was a distinct antioxidant phytotherapy to rescue neuronal oxidative stress, through blocking LPO, restoring endogenous antioxidant system, but not scavenging free radicals.

scholarly journals Meroterpenoid-Rich Fraction of the Ethanolic Extract from Sargassum serratifolium Suppressed Oxidative Stress Induced by Tert-Butyl Hydroperoxide in HepG2 Cells

Marine Drugs ◽  
2018 ◽  
Vol 16 (10) ◽  
pp. 374 ◽  
Author(s):  
Sujin Lim ◽  
Misung Kwon ◽  
Eun-Ji Joung ◽  
Taisun Shin ◽  
Chul-Woong Oh ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hepg2 Cells ◽  
Ethanolic Extract ◽  
Glutathione Depletion ◽  
Heme Oxygenase 1 ◽  
Dependent Manner ◽  
Butyl Hydroperoxide ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide ◽  
Sargassum Serratifolium

Sargassum species have been reported to be a source of phytochemicals, with a wide range of biological activities. In this study, we evaluated the hepatoprotective effect of a meroterpenoid-rich fraction of the ethanolic extract from Sargassum serratifolium (MES) against tert-butyl hydroperoxide (t-BHP)-treated HepG2 cells. Treatment with MES recovered the cell viability from the t-BHP-induced oxidative damage in a dose-dependent manner. It suppressed the reactive oxygen species production, lipid peroxidation, and glutathione depletion in the t-BHP-treated HepG2 cells. The activity of the antioxidants induced by t-BHP, including superoxide dismutase (SOD) and catalase, was reduced by the MES treatment. Moreover, it increased the nuclear translocation of nuclear factor erythroid 2-related factor 2, leading to the enhanced activity of glutathione S transferase, and the increased production of heme oxygenase-1 and NAD(P)H:quinine oxidoreductase 1 in t-BHP-treated HepG2 cells. These results demonstrate that the antioxidant activity of MES substituted the activity of the SOD and catalase, and induced the production of detoxifying enzymes, indicating that MES might be used as a hepatoprotectant against t-BHP-induced oxidative stress.

scholarly journals Phloretin ameliorates hepatic steatosis through regulation of lipogenesis and Sirt1/AMPK signaling in obese mice

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chian-Jiun Liou ◽  
Shu-Ju Wu ◽  
Szu-Chuan Shen ◽  
Li-Chen Chen ◽  
Ya-Ling Chen ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Fatty Acid ◽  
Hepatic Steatosis ◽  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Fatty Acid Synthase ◽  
Regulatory Element ◽  
Liver Lipid ◽  
Obese Mice ◽  
Alcoholic Fatty Liver

Abstract Background Phloretin is isolated from apple trees and could increase lipolysis in 3T3-L1 adipocytes. Previous studies have found that phloretin could prevent obesity in mice. In this study, we investigated whether phloretin ameliorates non-alcoholic fatty liver disease (NAFLD) in high-fat diet (HFD)-induced obese mice, and evaluated the regulation of lipid metabolism in hepatocytes. Methods HepG2 cells were treated with 0.5 mM oleic acid to induce lipid accumulation, and then treated with phloretin to evaluate the molecular mechanism of lipogenesis. In another experiment, male C57BL/6 mice were fed normal diet or HFD (60% fat, w/w) for 16 weeks. After the fourth week, mice were treated with or without phloretin by intraperitoneal injection for 12 weeks. Results Phloretin significantly reduced excessive lipid accumulation and decreased sterol regulatory element-binding protein 1c, blocking the expression of fatty acid synthase in oleic acid-induced HepG2 cells. Phloretin increased Sirt1, and phosphorylation of AMP activated protein kinase to suppress acetyl-CoA carboxylase expression, reducing fatty acid synthesis in hepatocytes. Phloretin also reduced body weight and fat weight compared to untreated HFD-fed mice. Phloretin also reduced liver weight and liver lipid accumulation and improved hepatocyte steatosis in obese mice. In liver tissue from obese mice, phloretin suppressed transcription factors of lipogenesis and fatty acid synthase, and increased lipolysis and fatty acid β-oxidation. Furthermore, phloretin regulated serum leptin, adiponectin, triglyceride, low-density lipoprotein, and free fatty acid levels in obese mice. Conclusions These findings suggest that phloretin improves hepatic steatosis by regulating lipogenesis and the Sirt-1/AMPK pathway in the liver.

scholarly journals S-Allyl Cysteine Alleviates Hydrogen Peroxide Induced Oxidative Injury and Apoptosis through Upregulation of Akt/Nrf-2/HO-1 Signaling Pathway in HepG2 Cells

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Chitra Basu ◽  
Runa Sur
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Oxidative Damage ◽  
Hepg2 Cells ◽  
Liver Diseases ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Dependent Manner ◽  
Cell Viability Assay

Hydrogen peroxide (H2O2) mediated oxidative stress leading to hepatocyte apoptosis plays a pivotal role in the pathophysiology of several chronic liver diseases. This study demonstrates that S-allyl cysteine (SAC) renders cytoprotective effects on H2O2 induced oxidative damage and apoptosis in HepG2 cells. Cell viability assay showed that SAC protected HepG2 cells from H2O2 induced cytotoxicity. Further, SAC treatment dose dependently inhibited H2O2 induced apoptosis via decreasing the Bax/Bcl-2 ratio, restoring mitochondrial membrane potential (∆Ψm), inhibiting mitochondrial cytochrome c release, and inhibiting proteolytic cleavage of caspase-3. SAC protected cells from H2O2 induced oxidative damage by inhibiting reactive oxygen species accumulation and lipid peroxidation. The mechanism underlying the antiapoptotic and antioxidative role of SAC is the induction of the heme oxygenase-1 (HO-1) gene in an NF-E2-related factor-2 (Nrf-2) and Akt dependent manner. Specifically SAC was found to induce the phosphorylation of Akt and enhance the nuclear localization of Nrf-2 in cells. Our results were further confirmed by specific HO-1 gene knockdown studies which clearly demonstrated that HO-1 induction indeed played a key role in SAC mediated inhibition of apoptosis and ROS production in HepG2 cells, thus suggesting a hepatoprotective role of SAC in combating oxidative stress mediated liver diseases.

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