Procyanidin B2 Alleviates Palmitic Acid-Induced Injury in HepG2 Cells via Endoplasmic Reticulum Stress Pathway

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome featuring ectopic lipid accumulation in hepatocytes. NAFLD has been a severe threat to humans with a global prevalence of over 25% yet no approved drugs for the treatment to date. Previous studies showed that procyanidin B2 (PCB2), an active ingredient from herbal cinnamon, has an excellent hepatoprotective effect; however, the mechanism remains inconclusive. The present study aimed to investigate the protective effect and underlying mechanism of PCB2 on PA-induced cellular injury in human hepatoma HepG2 cells. Our results showed that PA-induced oxidative stress, calcium disequilibrium, and subsequent endoplasmic reticulum stress (ERS) mediated cellular injury, with elevated protein levels of GRP78, GRP94, CHOP, and hyperphosphorylation of PERK and IRE1α as well as the increased ratio of Bax/Bcl-2, which was restored by PCB2 in a concentration-dependent manner, proving the excellent antiapoptosis effect. In addition, 4-phenylbutyric acid (4-PBA), the ER stress inhibitor, increased cell viability and decreased protein levels of GRP78 and CHOP, which is similar to PCB2, and thapsigargin (TG), the ER stress agonist, exhibited conversely meanwhile partly counteracted the hepatic protection of PCB2. What is more, upregulated protein expression of p-IKKα/β, p-NF-κB p65, NLRP3, cleaved caspase 1, and mature IL-1β occurred in HepG2 cells in response to PA stress while rescued with the PCB2 intervention. In conclusion, our study demonstrated that PA induces ERS in HepG2 cells and subsequently activates downstream NLRP3 inflammasome-mediated cellular injury, while PCB2 inhibits NLRP3/caspase 1/IL-1β pathway, inflammation, and apoptosis with the presence of ERS, thereby promoting cell survival, which may provide pharmacological evidence for clinical approaches on NAFLD.

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Polyhexamethyleneguanidine Phosphate-Induced Cytotoxicity in Liver Cells Is Alleviated by Tauroursodeoxycholic Acid (TUDCA) via a Reduction in Endoplasmic Reticulum Stress

Cells ◽

10.3390/cells8091023 ◽

2019 ◽

Vol 8 (9) ◽

pp. 1023 ◽

Cited By ~ 3

Author(s):

Sou Hyun Kim ◽

Doyoung Kwon ◽

Seunghyun Lee ◽

Sung Hwan Ki ◽

Hye Gwang Jeong ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Er Stress ◽

Hepg2 Cells ◽

Apoptotic Cell ◽

Liver Cells ◽

Dependent Manner ◽

Apoptotic Pathway ◽

Tauroursodeoxycholic Acid ◽

Chemical Chaperone

Polyhexamethyleneguanidine phosphate (PHMG-P) is a widely used polymeric antimicrobial agent known to induce significant pulmonary toxicity. Several studies have reported that the liver also can be a target organ of polyhexamethyleneguanidine (PHMG) toxicity, but the exact effect of this compound on liver cells is not well understood. To identify the mechanism of PHMG hepatotoxicity, HepG2 cells were exposed to PHMG-P for 72 h. The cell viability was significantly decreased by PHMG-P in a time- and concentration-dependent manner. The mitochondrial membrane potential was markedly reduced by PHMG-P and the apoptotic signaling cascade was activated. The increases observed in C/EBP homologous protein (CHOP), p-IRE, and p-JNK levels in PHMG-P-treated cells indicated the induction of endoplasmic reticulum stress. To verify the role of ER stress in PHMG-P-induced cytotoxicity, HepG2 cells were pretreated with the chemical chaperone, tauroursodeoxycholic acid (TUDCA) and then co-treated with TUDCA and PHMG-P for 24 h. Interestingly, TUDCA inhibited PHMG-P-induced ER stress and cytotoxicity in a dose-dependent manner. The apoptotic cell death and mitochondrial depolarization were also prevented by TUDCA. The proteins involved in the apoptotic pathway were all normalized to their control levels in TUDCA-treated cells. In conclusion, the results suggest that PHMG-P induced significant cytotoxicity in liver cells and ER stress-mediated apoptosis, which may be an important mechanism mediating this hepatotoxicity.

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Endoplasmic Reticulum Stress Is Involved in Baicalin Protection on Chondrocytes From Patients With Osteoarthritis

Dose-Response ◽

10.1177/1559325818810636 ◽

2018 ◽

Vol 16 (4) ◽

pp. 155932581881063 ◽

Cited By ~ 1

Author(s):

Jiangang Cao ◽

Yu Zhang ◽

Tianyi Wang ◽

Bo Li

Keyword(s):

Oxidative Stress ◽

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Cell Viability ◽

Er Stress ◽

Messenger Rna ◽

Cell Counting ◽

Protective Effects ◽

Gene Expressions ◽

Protein Levels

Osteoarthritis (OA) affects elderly population worldwide and endoplasmic reticulum (ER) stress is known to be positively correlated with OA development. Previous reports prove the cytoprotective effects of baicalin on chondrocytes, whereas the mechanisms are hardly reported. Hence, we aimed to investigate the links between OA, ER stress, and baicalin. Chondrocytes from patients with OA were subjected to H2O2 treatment with or without baicalin pretreatment, and cell viability was assessed via Cell Counting Kit-8. Messenger RNA (mRNA) amounts of apoptosis-related genes (Bax, Bcl-2, and Caspase-3), extracellular matrix (ECM)-related genes (Collange I, Collange II, Aggrecan, and Sox9) and ER stress hallmarks (binding immunoglobulin protein [BiP] C/EBP homologous protein [CHOP]) were evaluated via quantitative real-time PCR. Bax, Bcl-2, BiP, and CHOP protein levels were analyzed via Western blot. Baicalin suppressed the changes in cell viability and apoptosis-related gene expressions caused by H2O2. Reactive oxygen species and glutathione/oxidized glutathione assay showed that H2O2 enhanced oxidative stress. Baicalin suppressed H2O2-induced downregulation of mRNA expression of ECM-related genes. Moreover, baicalin reduced H2O2-stimulated increase in oxidative stress and the expression of ER stress hallmarks. Endoplasmic reticulum stress inducer abolished the protective activities, whereas ER stress inhibitor did not exhibit extra protective effects. Baicalin pretreatment protected patient-derived chondrocytes from H2O2 through ER stress inhibition.

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Lipid-Induced Endoplasmic Reticulum Stress in Liver Cells Results in Two Distinct Outcomes: Adaptation with Enhanced Insulin Signaling or Insulin Resistance

Endocrinology ◽

10.1210/en.2011-1881 ◽

2012 ◽

Vol 153 (5) ◽

pp. 2164-2177 ◽

Cited By ~ 49

Author(s):

Caroline S. Achard ◽

D. Ross Laybutt

Keyword(s):

Insulin Resistance ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Insulin Signaling ◽

Hepg2 Cells ◽

Glycogen Synthesis ◽

Liver Cells ◽

Dependent Manner ◽

Akt Phosphorylation ◽

High Level

Chronically elevated fatty acids contribute to insulin resistance through poorly defined mechanisms. Endoplasmic reticulum (ER) stress and the subsequent unfolded protein response (UPR) have been implicated in lipid-induced insulin resistance. However, the UPR is also a fundamental mechanism required for cell adaptation and survival. We aimed to distinguish the adaptive and deleterious effects of lipid-induced ER stress on hepatic insulin action. Exposure of human hepatoma HepG2 cells or mouse primary hepatocytes to the saturated fatty acid palmitate enhanced ER stress in a dose-dependent manner. Strikingly, exposure of HepG2 cells to prolonged mild ER stress activation induced by low levels of thapsigargin, tunicamycin, or palmitate augmented insulin-stimulated Akt phosphorylation. This chronic mild ER stress subsequently attenuated the acute stress response to high-level palmitate challenge. In contrast, exposure of HepG2 cells or hepatocytes to severe ER stress induced by high levels of palmitate was associated with reduced insulin-stimulated Akt phosphorylation and glycogen synthesis, as well as increased expression of glucose-6-phosphatase. Attenuation of ER stress using chemical chaperones (trimethylamine N-oxide or tauroursodeoxycholic acid) partially protected against the lipid-induced changes in insulin signaling. These findings in liver cells suggest that mild ER stress associated with chronic low-level palmitate exposure induces an adaptive UPR that enhances insulin signaling and protects against the effects of high-level palmitate. However, in the absence of chronic adaptation, severe ER stress induced by high-level palmitate exposure induces deleterious UPR signaling that contributes to insulin resistance and metabolic dysregulation.

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Ghrelin Alleviates Endoplasmic Reticulum Stress in MC3T3E1 Cells by Inhibiting AMPK Phosphorylation

Oxidative Medicine and Cellular Longevity ◽

10.1155/2021/9940355 ◽

2021 ◽

Vol 2021 ◽

pp. 1-14

Author(s):

Xue Lv ◽

Qianping Zhang ◽

Bingfei Cheng ◽

Ying Xin ◽

Jun Wang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Energy Homeostasis ◽

Marker Genes ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Expression Of Genes ◽

Species Production ◽

Related Proteins

Ghrelin is a gastric endocrine peptide that has been found to be involved in the process of energy homeostasis and bone physiology in recent years. To explore the effects of ghrelin on endoplasmic reticulum stress (ERS) in MC3T3E1 cells and its possible mechanism, an ERS model was induced by tunicamycin (TM) in the osteoblast line MC3T3E1. TM at 1.5 μg/mL was selected as the experimental concentration found by CCK8 assay. Through the determination of apoptosis, reactive oxygen species production, and endoplasmic reticulum stress-related gene expression, we found that ERS induced by TM can be relieved by ghrelin in a concentration-dependent manner ( P < 0.001 ). Compared with the TM group, ghrelin reduced the expression of ERS-related marker genes induced by TM. Compared with the GSK621 + TM group without ghrelin pretreatment, the mRNA expression of genes in the ghrelin pretreatment group decreased significantly ( P < 0.001 ). The results of protein analysis showed that the levels of BIP, p-AMPK, and cleaved-caspase3 in the TM group increased significantly, while the levels decreased after ghrelin pretreatment. In group GSK621 + TM compared with group GSK621 + ghrelin+TM, ghrelin pretreatment significantly reduced the level of p-AMPK, which is consistent with the trend of the ERS-related proteins BIP and cleaved-caspase3. In conclusion, ghrelin alleviates the ERS induced by TM in a concentration-dependent manner and may or at least partly alleviate the apoptosis induced by ERS in MC3T3E1 cells by inhibiting the phosphorylation of AMPK.

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Exogenous acylated ghrelin promotes but un-acylated ghrelin prevents hepatic steatosis by modulating peripheral insulin resistance and hepatic oxidative and endoplasmic reticulum stress

Journal of Contemporary Medical Sciences ◽

10.22317/jcms.v7i3.998 ◽

2021 ◽

Vol 7 (3) ◽

Keyword(s):

Insulin Resistance ◽

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Er Stress ◽

Hepatic Steatosis ◽

Fatty Acid Synthase ◽

Lipid Synthesis ◽

Acylated Ghrelin ◽

Mrna Levels ◽

Protein Levels

Objectives: This study tested the effects of acylated (AG and un-acylated ghrelin (UAG) on hepatic lipid synthesis and insulin resistance (IR) from prospective to their effect on endoplasmic reticulum stress and investigated the possible underlying mechanisms. Methods: Healthy rats were divided as 4 groups (n=12/each) as control, control + AG, control + UAG, and control + AG + UAG (1:1). GA or UAG were given subcutaneously (200 ng/kg/each) for 8 weeks. Results: AG increased fasting levels of glucose and insulin resistance, increased hepatic glucose production, and impaired glucose and insulin tolerance. Besides, it increased serum levels of free fatty acids (FFAs), enhanced serum and hepatic levels of triglycerides and cholesterol, and increased lipid deposition in the livers of rats. Concomitantly, it stimulated the mRNA levels of SREBP1/2, fatty acid synthase, and protein levels of all arms of ER stress including Xbp-1, CHOP, ATF-6, and p-eIF2α, thus activating lipid synthesis and ER stress. It also reduced protein levels of p-IRS (Tyr612), p-Akt (Ser307), and increased levels of ROS, TNF-α, IL-6, and protein levels of cleaved caspase-12, p-IRS (Ser307), and p-JNK (The183/Tyr186) in rats’ livers. Administration of UAG alone or in combination with AG produced contradictory effects. However, both AG and UAG significantly increased mRNA levels of AMPK and PPARα suggesting FAs oxidation. Conclusion: AG induces hepatic steatosis and suppresses hepatic insulin signaling mainly by inducing peripheral IR that is associated with hepatic oxidative stress, inflammation, and ER stress. However, UAG alone or in combination exerts opposite effects.

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A Dipeptidyl Peptidase IV Inhibitory Peptide Relieves Palmitic Acid-Induced Endoplasmic Reticulum Stress in HepG2 Cells Independently of Inhibiting Dipeptidyl Peptidase IV Activity

Food & Function ◽

10.1039/d1fo02283k ◽

2021 ◽

Author(s):

Ritian Jin ◽

Haowei Ren ◽

Minhe Liao ◽

Jiaqi Shang ◽

Dangfeng Wang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Palmitic Acid ◽

Er Stress ◽

Hepg2 Cells ◽

Dipeptidyl Peptidase ◽

Dipeptidyl Peptidase Iv ◽

Inhibitory Peptide ◽

Dpp Iv

The peptide VLATSGPG (VLA) is known to inhibit dipeptidyl peptidase IV (DPP-IV), although its mechanism in relieving endoplasmic reticulum (ER) stress is unclear. In this study, we found that treating...

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Different Induction Effects of Praziquantel Racemate and Enantiomers on the Enzyme CYP3A4 Mediated by Pregnane X Receptor and Its Variants

Current Drug Metabolism ◽

10.2174/1389200221999210104204057 ◽

2021 ◽

Vol 21 ◽

Author(s):

Ran Meng ◽

Xueli Zhang ◽

Haina Wang ◽

Danlu Zhang ◽

Xin Zhao

Keyword(s):

Hepg2 Cells ◽

Pregnane X Receptor ◽

Luciferase Reporter ◽

Dependent Manner ◽

Luciferase Reporter Gene ◽

Concentration Dependent Manner ◽

Protein Levels ◽

Mrna And Protein Expression ◽

Polymerase Chain ◽

Expression Plasmids

Background: Praziquantel (PZQ), which possesses an asymmetric center, is classified as a pyrazinoisoquinoline and has been the mainstay in the treatment of schistosomiasis since 1980. PZQ undergoes a pronounced first-pass metabolism in the liver through the CYP450 system which could be mediated by nuclear receptors. Objective: The purpose of this study was to investigate the possible different induction effects of CYP3A4 by PZQ racemate and enantiomers via the pregnane X receptor (PXR) and the effect of PXR polymorphism on the induction potency of PZQs. Methods: The dual-luciferase reporter gene systems constructed in HepG2 cells were used to measure the abilities of PZQs to induce CYP3A4 expression mediated by PXR. The mRNA and protein levels of CYP3A4 were evaluated by polymerase chain reaction (PCR) and western blotting, respectively. Results: In HepG2 cells transfected with PXRwt, PXR158, PXR163, PXR370 or PXR403 expression plasmids, PZQ racemate and its enantiomers up-regulated the luciferase activity in a concentration-dependent manner, while reaching saturation after transfected with PXR379 expression plasmids. The mRNA and protein expression of CYP3A4 was effectively activated in PXR-transfected HepG2 cells. The induction ability of CYP3A4 mediated by PXR activation by PZQ racemate and its enantiomers were statistically different between the same PXR group and different PXR groups. Conclusion: The enantioselective induction effects of PZQs on CYP3A4 were related to the enantioselective activations of PXR by PZQs and were influenced by the PXR gene polymorphism. These findings provide a basis for further understanding the enantiomeric metabolism and the variable efficacy of PZQs.

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Endoplasmic Reticulum Stress Promotes The Release of Exosomal PD-L1 From Head and Neck Cancer Cells and Facilitates M2 Macrophage Differentiation

10.21203/rs.3.rs-574378/v1 ◽

2021 ◽

Author(s):

Yi Yuan ◽

Pengfei Jiao ◽

Zeyu Wang ◽

Mengqi Chen ◽

Hongming Du ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Er Stress ◽

Immune Surveillance ◽

M2 Macrophage ◽

Macrophage Differentiation ◽

Poor Overall Survival ◽

Macrophage Polarisation ◽

Protein Levels

Abstract Background Endoplasmic reticulum stress (ER stress) fosters cancer cell escape from immune surveillance and upregulate PD-L1 expression, but the mechanisms remain unclear. Methods We analyzed protein levels by immunofluorescence and Western blotting, RNA levels by qRT-PCR. Exosomes were injected intravenously through the tail vein into 6-week-old nude mice once every other day for a total of 10 injections Results Expression of some ER stress markers, including GRP78 (glucose-regulated protein 78), ATF6 (activating transcription factor 6) and PERK (PKR-like endoplasmic reticulum kinase), was upregulated in OSCC tissues and correlated with poor overall survival. The level of ER stress-related proteins positively correlated with a cluster of PD-L1 expression and macrophage infiltration in OSCC tissues. PD-L1 expression in OSCC tissues was negatively correlated with cumulative survival. Incubation with Exo-ER upregulated PD-L1 levels in macrophages in vitro and vivo, and upregulation of PD-L1 promoted macrophage polarisation towards the M2 subtype. Conclusions ER stress induced exosome secretion by OSCC cells and PD-L1 expression in macrophages to promote M2 macrophage differentiation. A novel exosome-modulated mechanism was delineated for OSCCs-macropahge crosstalk that drove tumor growth and should be explored for its therapeutic utility.

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Role of the Death Receptor and Endoplasmic Reticulum Stress Signaling Pathways in Polyphyllin I-Regulated Apoptosis of Human Hepatocellular Carcinoma HepG2 Cells

BioMed Research International ◽

10.1155/2018/5241941 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 7

Author(s):

Qihui Luo ◽

Dandan Yang ◽

Qi Qi ◽

Chao Huang ◽

Bing Chen ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Er Stress ◽

Signaling Pathways ◽

Hepg2 Cells ◽

Death Receptor ◽

Receptor Signaling ◽

Death Receptor Signaling

Polyphyllin has been reported to exhibit anticancer effects against various types of cancer via the proapoptotic signaling pathway. The aim of the present study was to investigate the role of the endoplasmic reticulum stress and death receptor signaling pathways in PPI-induced apoptosis of human hepatocellular carcinoma HepG2 cells. Analysis demonstrated that PPI could significantly inhibit the proliferation and induce apoptosis of HepG2 cells in a dose- and time-dependent manner. Investigation into the molecular mechanism of PPI indicated that PPI notably mediated ER stress activation via IRE-1 overexpression and activation of the caspase-12 to protect HepG2 cells against apoptosis. In addition, PPI markedly induced the expression of death receptors signaling pathways-associated factors, including tumor necrosis factor (TNF) receptor 1/TNF-αand FAS/FASL. Additionally, suppression of the death receptor signaling pathways with a caspase-8 inhibitor, Z-IETD-FMK, revealed an increase in the death rate and apoptotic rate of HepG2 cells. Collectively, the findings of the present study suggested that the ER stress and death receptor signaling pathways were associated with PPI-induced HepG2 cell apoptosis; however, endoplasmic reticulum stress may serve a protective role in this process. The combination of PPI and Z-IETD-FMK may activate necroptosis, which enhances apoptosis. Therefore, the results of the present study may improve understanding regarding the roles of signaling pathways in PPI regulated apoptosis and contribute to the development of novel therapies for the treatment of HCC.

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Contributions of TRPV1, endovanilloids, and endoplasmic reticulum stress in lung cell death in vitro and lung injury

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00231.2011 ◽

2012 ◽

Vol 302 (1) ◽

pp. L111-L119 ◽

Cited By ~ 28

Author(s):

Karen C. Thomas ◽

Jessica K. Roberts ◽

Cassandra E. Deering-Rice ◽

Erin G. Romero ◽

Randal O. Dull ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Lung Injury ◽

Endoplasmic Reticulum Stress ◽

Er Stress ◽

Dry Weight ◽

Lung Cells ◽

Transient Receptor Potential Vanilloid ◽

Dependent Manner ◽

Wild Type ◽

Gadd153 Expression

Endogenous agonists of transient receptor potential vanilloid-1 (TRPV1) (endovanilloids) are implicated as mediators of lung injury during inflammation. This study tested the hypothesis that endovanilloids produced following lipopolysaccharide (LPS) treatment activate TRPV1 and cause endoplasmic reticulum stress/GADD153 expression in lung cells, representing a mechanistic component of lung injury. The TRPV1 agonist nonivamide induced GADD153 expression and caused cytotoxicity in immortalized and primary human bronchial, bronchiolar/alveolar, and microvascular endothelial cells, proportional to TRPV1 mRNA expression. In CF-1 mice, Trpv1 mRNA was most abundant in the alveoli, and intratracheal nonivamide treatment promoted Gadd153 expression in the alveolar region. Treatment of CF-1 mice with LPS increased Gadd153 in the lung, lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, and lung wet-to-dry weight ratio. Cotreating mice with LPS and the TRPV1 antagonist LJO-328 reduced Gadd153 induction and LDH in BAL but did not inhibit increases in lung wet-to-dry ratio. In Trpv1−/− mice treated with LPS, Gadd153 induction and LDH in BAL were reduced relative to wild-type mice, and the wet-to-dry weight ratios of lungs from both wild-type and Trpv1−/− mice decreased. Organic extracts of blood collected from LPS-treated mice were more cytotoxic to TRPV1-overexpressing cells compared with BEAS-2B cells and extracts from control mice, however, most pure endovanilloids did not produce cytotoxicity in a characteristic TRPV1-dependent manner. Collectively, these data indicate a role for TRPV1, and endogenous TRPV1 agonists, in ER stress and cytotoxicity in lung cells but demonstrate that ER stress and cytotoxicity are not essential for pulmonary edema.

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