Inhibition Of Stress Research Articles

C/EBPα alleviates hepatic ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress via HDAC1-mediated deacetylation of ATF4.

Hepatic ischemia-reperfusion (IR) injury is a complex systemic process causing a series clinical problem. C/EBPα is a key transcription factor for hepatocyte function, but its role and mechanism in regulating hepatic IR injury are largely unknown. Occluding portal vein and hepatic artery was used to establish a mouse model of hepatic IR injury. C/EBPα expression was decreased in IR-injured liver compared with the sham, accompanied by increased contents of serum alanine transaminase(ALT), aspartate transaminase(AST),high mobility group box-1, and proportion of hepatic cells. Oxygen and glucose deprivation/recovery (OGD/R) was used to establish a cellular hepatic IR model in WRL-68 hepatocytes in vitro, and C/EBPα was overexpressed in the hepatocytes to evaluate its effect on hepatic IR injury. OGD/R promoted oxidative stress, cell apoptosis and endoplasmic reticulum (ER) stress in hepatocytes, which was reversed by C/EBPα overexpression. Then, we found that C/EBPα promoted histone deacetylase 1 (HDAC1) transcription through binding to HDAC1 promoter. Moreover, HDAC1 deacetylated the activating transcription factor 4 (ATF4), a key positive regulator of ERstress. Trichostatin-A(an HDAC inhibitor) or ATF4 overexpression reversed the improvement of C/EBPα on OGD/R-induced ER stress and hepatocyte dysfunction. 4-Phenylbutyric acid(an endoplasmic reticulum stress inhibitor) also reversed the hepatic IR injury induced by ATF4 overexpression. Finally, lentivirus-mediated C/EBPα overexpression vector was applied to administrate hepatic IR mice, and the results showed that C/EBPα overexpression ameliorated IR-inducedhepatic injury, manifesting with reduced ALT/AST, oxidative stress and ER stress. Altogether, our findings suggested that C/EBPα ameliorated hepatic IR injury by inhibiting ER stress via HDAC1-mediated deacetylation of ATF4 promoter.

Role of autophagy in betaine-promoted hepatoprotection against non-alcoholic fatty liver disease in mice

Betaine, a compound found in plants and sea foods, is known to be beneficial against non-alcoholic fatty liver disease (NAFLD), but its hepatoprotective and anti-steatogenic mechanisms have been not fully understood. In the present study, we investigated the mechanisms underlying betaine-mediated alleviation of NAFLD induced by a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) in mice, with special focus on the contribution of betaine-stimulated autophagy to NAFLD prevention. Male ICR mice were fed a CDAHFD with or without betaine (0.2–1% in drinking water) for 1 week. Betaine ameliorated the CDAHFD-induced fatty liver by restoring sulfur amino acid (SAA)-related metabolites, such as S-adenosylmethionine and homocysteine, and the phosphorylation of AMPK and ACC. In addition, it reduced the CDAHFD-induced ER stress (BiP, ATF6, and CHOP) and apoptosis (Bax, cleaved caspase-3, and cleaved PARP); however, it induced autophagy (LC3II/I and p62) which was downregulated by CDAHFD. To determine the role of autophagy in the improvement of NAFLD, chloroquine (CQ), an autophagy inhibitor, was injected into the mice fed a CDAHFD and betaine (0.5 % in drinking water). CQ did not affect SAA metabolism but reduced the beneficial effects of betaine as shown by the increases of hepatic lipids, ER stress, and apoptosis. Notably, the betaine-induced improvements in lipid metabolism determined by protein levels of p-AMPK, p-ACC, PPARα, and ACS1, were reversed by CQ. Thus, the results of this study suggest that the activation of autophagy is an important upstream mechanism for the inhibition of steatosis, ER stress, and apoptosis by betaine in NAFLD.

A forebrain-hypothalamic ER stress driven circuit mediates hepatic steatosis during obesity

ObjectiveNon-alcoholic fatty liver disease (NAFLD) affects 1 in 3 adults and contributes to advanced liver injury and cardiometabolic disease. While recent evidence points to involvement of the brain in NAFLD, the downstream neural circuits and neuronal molecular mechanisms involved in this response, remain unclear. Here, we investigated the role of a unique forebrain-hypothalamic circuit in NAFLD. MethodsChemogenetic activation and inhibition of circumventricular subfornical organ (SFO) neurons that project to the paraventricular nucleus of the hypothalamus (PVN; SFO→PVN) in mice were used to study the role of SFO→PVN signaling in NAFLD. Novel scanning electron microscopy techniques, histological approaches, molecular biology techniques, and viral methodologies were further used to delineate the role of endoplasmic reticulum (ER) stress within this circuit in driving NAFLD. ResultsIn lean animals, acute chemogenetic activation of SFO→PVN neurons was sufficient to cause hepatic steatosis in a liver sympathetic nerve dependent manner. Conversely, inhibition of this forebrain-hypothalamic circuit rescued obesity-associated NAFLD. Furthermore, dietary NAFLD is associated with marked ER ultrastructural alterations and ER stress in the PVN, which was blunted following reductions in excitatory signaling from the SFO. Finally, selective inhibition of PVN ER stress reduced hepatic steatosis during obesity. ConclusionsCollectively, these findings characterize a previously unrecognized forebrain-hypothalamic-ER stress circuit that is involved in hepatic steatosis, which may point to future therapeutic strategies for NAFLD.

Nitric oxide-induced endoplasmic reticulum stress of Schistosoma japonicum inhibits the worm development in rats

Schistosomiasis, caused by Schistosoma spp., is a zoonotic parasitic disease affecting human health. Rattus norvegicus (rats) are a non-permissive host of Schistosoma, in which the worms cannot mature and cause typical egg granuloma. We previously demonstrated that inherent high levels of nitric oxide (NO), produced by inducible NO synthase (iNOS), is a key molecule in blocking the development of S. japonicum in rats. To further explore the mechanism of NO inhibiting S. japonicum development in rats, we performed S-nitrosocysteine proteomics of S. japonicum collected from infected rats and mice. The results suggested that S. japonicum in rats may have undergone endoplasmic reticulum (ER) stress. Interestingly, we found that the ER of S. japonicum in rats showed marked damage, while the ER of the worm in iNOS−/− rats and mice were relatively normal. Moreover, the expression of ER stress markers in S. japonicum from WT rats was significantly increased, compared with S. japonicum from iNOS−/− rats and mice. Using the NO donor sodium nitroprusside in vitro, we demonstrated that NO could induce ER stress in S. japonicum in a dose-dependent manner, and the NO-induced ER stress in S. japonicum could be inhibited by ER stress inhibitor 4-Phenyl butyric acid. We further verified that inhibiting ER stress of S. japonicum in rats promoted parasite development and survival. Furthermore, we demonstrated that NO-induced ER stress of S. japonicum was related to the efflux of Ca2+ from ER and the impairment of mitochondrial function. Collectively, these findings show that high levels of NO in rats could induce ER stress in S. japonicum by promoting the efflux of Ca2+ from ER and damaging the mitochondrial function, which block the worm development. Thus, this study further clarifies the mechanism of anti-schistosome in rats and provides potential strategies for drug development against schistosomiasis and other parasitosis.

Portulaca Oleracea L. (Purslane) Extract Protects Endothelial Function by Reducing Endoplasmic Reticulum Stress and Oxidative Stress through AMPK Activation in Diabetic Obese Mice.

Portulaca oleracea L. (purslane) is a food and a traditional drug worldwide. It exhibits anti-inflammatory, anti-oxidative, anti-tumor, and anti-diabetic bioactivities; but its activity on diabetic-associated endothelial dysfunction is unknown. This study aimed to investigate the effect of purslane on endothelial function and the underlying mechanisms. Male C57BL/6 mice had 14-week ad libitum access to a high-fat rodent diet containing 60% kcal% fat to induce obesity and diabetes whereas purslane extract (200 mg/kg/day) was administered during the last 4 weeks via intragastric gavage. Primary rat aortic endothelial cells and isolated mouse aortas were cultured with a risk factor, high glucose or tunicamycin, together with purslane extract. By ESI-QTOF-MS/MS, flavonoids and their glycoside products were identified in the purslane extract. Exposure to high glucose or tunicamycin impaired acetylcholine-induced endothelium-dependent relaxations in aortas and induced endoplasmic reticulum (ER) stress and oxidative stress with the downregulation of 5' AMP-activated protein kinase (AMPK)/ endothelial nitric oxide synthase (eNOS) signaling. Co-incubation with purslane significantly ameliorated these impairments. The effects of purslane were abolished by Compound C (AMPK inhibitor). Four-week purslane treatment ameliorated aortic relaxations, ER stress, and oxidative stress in diabetic obese mice. This study supported that purslane protected endothelial function, and inhibited ER stress and oxidative stress in vasculature through AMPK/eNOS activation, revealing its therapeutic potential against vascular complications in diabetes.

Artichoke (Cynara scolymus L.) water extract alleviates palmitate-induced insulin resistance in HepG2 hepatocytes via the activation of IRS1/PI3K/AKT/FoxO1 and GSK-3β signaling pathway

BackgroundArtichoke (Cynara scolymus L.) is a typical element of a traditional Mediterranean diet and has potential health advantages for insulin resistance (IR) and type 2 diabetes mellitus (T2DM). This study aims to evaluate the effect and underlying mechanism of artichoke water extract (AWE) on palmitate (PA)-induced IR in human hepatocellular carcinoma (HepG2) cells.MethodsThe effect of AWE on cell viability was determined using CCK8 assay. Cellular glucose uptake, glucose consumption, glucose production, and glycogen content were assessed after AWE treatment. The gene expression and protein levels were examined by real-time polymerase chain reaction (qRT-PCR) and western blotting.ResultsThe results showed that AWE dose-dependently increased cell viability in IR HepG2 cells (P < 0.01). AWE treatment significantly promoted glucose uptake and consumption, decreased glucose production, and increased the cellular glycogen content in IR HepG2 cells (P < 0.01). Mechanistically, AWE elevated the phosphorylation and total protein levels of major insulin signaling molecules in IR HepG2 cells, which resulted in a decrease in the expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) and the inhibition of glycogen synthase (GS) phosphorylation in IR HepG2 cells. Furthermore, the protective effect of AWE on IR HepG2 cells might be ascribed to the inhibition of the endoplasmic reticulum (ER) stress.ConclusionWe conclude that AWE may improve glucose metabolism by regulating IRS1/PI3K/AKT/FoxO1 and GSK-3β signaling associated with the inhibition of ER stress in IR HepG2 cells induced by PA.

Detrimental Role of CXCR3 in α-Naphthylisothiocyanate- and Triptolide-Induced Cholestatic Liver Injury.

The chemokine receptor CXCR3 is functionally pleiotropic, not only recruiting immune cells to the inflamed liver but also mediating the pathological process of cholestatic liver injury (CLI). However, the mechanism of its involvement in the CLI remains unclear. Both alpha-naphthylisothiocyanate (ANIT) and triptolide are hepatotoxicants that induce CLI by bile acid (BA) dysregulation, inflammation, and endoplasmic reticulum (ER)/oxidative stress. Through molecular docking, CXCR3 is a potential target of ANIT and triptolide. Therefore, this study aimed to investigate the role of CXCR3 in ANIT- and triptolide-induced CLI and to explore the underlying mechanisms. Wild-type mice and CXCR3-deficient mice were administered with ANIT or triptolide to compare CLI, BA profile, hepatic recruitment of IFN-γ/IL-4/IL-17+CD4+T cells, IFN-γ/IL-4/IL-17+iNKT cells and IFN-γ/IL-4+NK cells, and the expression of ER/oxidative stress pathway. The results showed that CXCR3 deficiency ameliorated ANIT- and triptolide-induced CLI. CXCR3 deficiency alleviated ANIT-induced dysregulated BA metabolism, which decreased the recruitment of IFN-γ+NK cells and IL-4+NK cells to the liver and inhibited ER stress. After triptolide administration, CXCR3 deficiency ameliorated dysregulation of BA metabolism, which reduced the migration of IL-4+iNKT cells and IL-17+iNKT cells and reduced oxidative stress through inhibition of Egr1 expression and AKT phosphorylation. Our findings suggest a detrimental role of CXCR3 in ANIT- and triptolide-induced CLI, providing a promising therapeutic target and introducing novel mechanisms for understanding cholestatic liver diseases.

Impact of endoplasmic reticulum stress on chondrocyte apoptosis in rat model of DDH.

Developmental dysplasia of the hip (DDH) is a developmental disorder characterized by acetabular dysplasia leading to early osteoarthritis. This study examines the role of endoplasmic reticulum stress (ERS) in chondrocyte apoptosis and cartilage degeneration within a DDH model. In the rat model of DDH, created using a swaddling technique, significant deformities in the femoral head and acetabulum were observed, alongside an upregulation of matrix metalloproteinase-13 in acetabular cartilage. We also noted increased levels of apoptosis and ERS-related factors in the acetabular cartilage of DDH models. Additionally, rat chondrocytes exposed to high-magnitude cyclic tensile strain (CTS, 1 Hz, 10% equibiaxial strain) in vitro exhibited elevated ERS and increased apoptosis. Importantly, treatment with the ERS inhibitor 4-phenylbutyric acid effectively suppressed apoptosis induced by CTS in chondrocytes. Our findings suggest that ERS contributes to the upregulation of apoptosis-related factors in chondrocytes within the DDH model, indicating the potential of ERS modulation as a therapeutic approach for DDH-related cartilage degeneration.

Inositol hexaphosphate enhances chemotherapy by reversing senescence induced by persistently activated PERK and diphthamide modification of eEF2

Oxaliplatin is an important initial chemotherapy benefiting advanced-stage colorectal cancer patients. Frustratingly, acquired oxaliplatin resistance always occurs after sequential chemotherapy with diverse antineoplastic drugs. Therefore, an exploration of the mechanism of oxaliplatin resistance formation in-depth is urgently needed. We generated oxaliplatin-resistant colorectal cancer models by four representative compounds, and RNA-seq revealed that oxaliplatin resistance was mainly the result of cells’ response to stimulus. Moreover, we proved persistent stimulus-induced endoplasmic reticulum stress (ERs) and associated cellular senescence were the core causes of oxaliplatin resistance. In addition, we screened diverse phytochemicals for ER inhibitors in silico, identifying inositol hexaphosphate (IP6), whose strong binding was confirmed by surface plasmon resonance. Finally, we confirmed the ability of IP6 to reverse colorectal cancer chemoresistance and investigated the mechanism of IP6 in the inhibition of diphthamide modification of eukaryotic elongation factor 2 (eEF2) and PERK activation. Our study demonstrated that oxaliplatin resistance contributed to cell senescence induced by persistently activated PERK and diphthamide modification of eEF2 levels, which were specifically reversed by combination therapy with IP6.

202 Endoplasmic reticulum stress inhibitor supports in vitro growth and maturation of bovine oocytes

202 Endoplasmic reticulum stress inhibitor supports in vitro growth and maturation of bovine oocytes

PDCD4 silencing alleviates KA‑induced neurotoxicity of HT22 cells by inhibiting endoplasmic reticulum stress via blocking the MAPK/NF‑κB signaling pathway.

Human programmed cell death 4 (PDCD4) has been reported to participate in multiple neurological diseases. However, the role of PDCD4 in epilepsy, as well as its underlying mechanism, remains unclear. To induce excitotoxicity, 100 µM kainic acid (KA) was applied for the stimulation of HT22 cells for 12 h. Initially, the mRNA and protein expression levels of PDCD4 were evaluated using reverse transcription-quantitative PCR and western blotting. A lactate dehydrogenase assay was performed to detect cell injury. Cell apoptosis was assessed using flow cytometry and western blotting was performed to determine the expression levels of apoptosis-related proteins. Oxidative stress was detected using dichlorodihydrofluorescein diacetate staining, and malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) assay kits. Furthermore, the expression levels of MAPK/NF-κB signaling-related proteins and endoplasmic reticulum (ER) stress-related proteins C/EBP homologous protein, glucose-regulated protein 78, activating transcription factor 4 and phosphorylated-eukaryotic initiation factor-2α were assessed by western blotting. It was revealed that PDCD4 expression was markedly elevated in KA-induced HT22 cells, whereas PDCD4 silencing alleviated KA-induced neurotoxicity of HT22 cells by alleviating cell injury and inhibiting apoptosis. In addition, PDCD4 silencing reduced the levels of reactive oxygen species and MDA, but elevated those of SOD and GSH-Px. PDCD4 silencing also suppressed ER stress by blocking the MAPK/NF-κB signaling pathway. By contrast, the MAPK agonist phorbol myristate acetate reversed the effects of PDCD4 silencing on KA-induced neurotoxicity and oxidative stress in HT22 cells. In conclusion, PDCD4 silencing alleviated KA-induced neurotoxicity and oxidative stress in HT22 cells by suppressing ER stress through the inhibition of the MAPK/NF-κB signaling pathway, which may provide novel insights into the treatment of epilepsy.

Capsaicin supplementation prevents western diet-induced hyperleptinemia by reducing endoplasmic reticulum stress in apolipoprotein E-deficient mice

Background: Endoplasmic reticulum (ER) stress implicated in leptin resistance in the diet-induced obesity, which can accelerate the development of atherosclerosis forms the background of this study.&#x0D; Objective: This study aimed to investigate the effect of capsaicin on hyperleptinema by inhibiting ER stress in apolipoprotein E-deficient (ApoE-/-) mice fed a western diet (WD).&#x0D; Design: ApoE -/- mice were assigned one of three experimental diets: WD (60% kcal from fat, n = 10), WD + 0.015% capsaicin (n = 10, w/w), and WD + 1% PBA (n = 10, w/w) for 12 weeks.&#x0D; Results: In metabolic parameters, supplementation of dietary capsaicin displayed marked reduction of body weight gain and adipose tissue weight, plasma leptin, total cholesterol, and hepatic triglyceride levels without change in the plasma insulin level compared with WD fed ApoE-/- mice after 12 weeks. Capsaicin supplementation also attenuated the protein expression of ER stress markers such as eukaryotic translational initiation factor 2α and C/EBP homology protein in the liver, as well as glucose-related protein 78 localization in the aorta, indicating that capsaicin inhibits diet-induced hyperleptinemia in part by regulating the protein expression involved in ER stress.&#x0D; Conclusion: Capsaicin, therefore, may have potential as a therapeutic agent for individuals with diet-induced hyperleptinemia

Dibromoacetonitrile induced autophagy by mediating the PERK signalling pathway and ROS interaction in HT22 cell

Dibromoacetonitrile (DBAN) is a high-risk haloacetonitrile (HAN) generated as a byproduct of chloramine disinfection in drinking water. DBAN-induced neurotoxicity in mouse hippocampal neuronal cells (HT22) and mammals was observed to be related to reactive oxygen species (ROS). ROS, endoplasmic reticulum stress (ERS) and autophagy play crucial roles in regulating a variety of cellular processes. However, whether ERS and autophagy are associated with HAN-responsive apoptosis remains unclear. This study indicated that DBAN (10 μM, 24 h) activated the ERS protein kinase like endoplasmic reticulum kinase (PERK) signaling pathway. The ERS inhibitor 4-phenylbutyric acid (4-PBA) reversed DBAN-inhibited cell viability and alleviated DBAN-induced apoptosis in HT22 cell, indicating that activation of the ERS PERK pathway mediates DBAN induced cytotoxicity. Moreover, DBAN activated autophagy. The autophagy inhibitor 3-methyladenine(3-MA) reversed DBAN-inhibited cell viability and alleviated DBAN-induced apoptosis in HT22 cell, suggesting that autophagy activation mediates DBAN-induced cell toxicity. Notably, the results showed that 4-PBA inhibited DBAN-activated autophagy, demonstrating that ERS–PERK promotes DBAN-induced cellular autophagy. Pretreatment with antioxidant N-acetylcysteine (NAC) inhibited the increase in ROS production and the activation of ERS, and protected cells from toxicity. Furthermore, 4-PBA pretreatment reduced the increase in ROS production, indicating that the ROS and PERK promote each other and form a positive feedback loop. ROS also promoted DBAN-induced autophagy. In summary, our findings indicate that DBAN induced autophagy by mediating the PERK signalling pathway and ROS interaction, leading to HT22 cell damage. Accordingly, targeting these pathogenic mechanisms may provide a potential target and theoretical basis for preventing and improving HAN-induced neurotoxicity.

IL-33/ST2L signaling alleviates diabetic nephropathy by regulating endoplasmic reticulum stress and apoptosis

ObjectiveDiabetic nephropathy (DN) is a serious chronic complication of diabetes mellitus (DM). Endoplasmic reticulum (ER) stress is an important factor in the regulation of pathological processes in DN, and excessive ER stress can lead to apoptosis. Although the IL-33/ST2 axis is known to be involved in diabetic kidney disease or related nephropathy, its role and molecular mechanisms remain poorly understood in terms of DN. The purpose of this study was to investigate the effects of IL-33/ST2 signaling on DN and to characterize the roles that ER stress and apoptosis play in DN.MethodsTo investigate this study, mice were randomly assigned into DN (induced by 0.1% STZ) and Control groups. Biochemical indices (FBG, BUN, UPR, UCE) were measured in serum and urine samples to reflect blood glucose and kidney damage. Quantitative real-time PCR, western blot, and immunofluorescence were used to assess gene and protein expression of the IL-33/ST2 axis and ER stress relative signaling molecule. Apoptosis was analyzed by flow cytometry.ResultsIL-33 levels are significantly increased in the kidneys of patients and mice with DN. Double immunofluorescence staining showed that IL-33 colocalized with CD31-positive endothelial cells. Treatment with IL-33 attenuated kidney injury in Streptozotocin (STZ)-treated mice. In vitro, we showed that IL-33 attenuated ER stress and apoptosis in glomerular endothelial cells. However, sST2 treatment significantly reversed these effects of IL-33.ConclusionTogether, these data suggest that IL-33/ST2 signaling mitigates STZ-induced renal damage, partly at least, by suppressing ER stress and apoptosis. Therefore, IL-33 may be an effective therapeutic target in DN.

Sestrin2 can alleviate endoplasmic reticulum stress to improve traumatic brain injury by activating AMPK/mTORC1 signaling pathway.

Traumatic brain injury (TBI), as a serious central nervous system disease, can result in severe neurological dysfunction or even disability and death of patients. The early and effective intervention of secondary brain injury can improve the prognosis of TBI. Endoplasmic reticulum (ER) stress is one of the main reasons to recover TBI. ER stress inhibition may be beneficial in treating TBI. Sestrin2 is a crucial regulator of ER stress, and its activation can significantly improve TBI. In this paper, we analyze the biological function of sestrin2, the latest findings on ER stress, and the relationship between ER stress and TBI. We elucidate the relationship of sestrin2 inhibiting ER stress via activating the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin complex 1 (MTORC1) signaling. Finally, we elaborate on the possible role of sestrin2 in TBI and explain how its activation potentially improves TBI.

Role of SYVN1 in the control of airway remodeling in asthma protection by promoting SIRT2 ubiquitination and degradation

BackgroundAsthma is a heterogenous disease that characterized by airway remodeling. SYVN1 (Synoviolin 1) acts as an E3 ligase to mediate the suppression of endoplasmic reticulum (ER) stress through ubiquitination and degradation. However, the role of SYVN1 in the pathogenesis of asthma is unclear.ResultsIn the present study, an ovalbumin (OVA)-induced murine model was used to evaluate the effect of SYVN1 on asthma. An increase in SYVN1 expression was observed in the lungs of mice after OVA induction. Overexpression of SYVN1 attenuated airway inflammation, goblet cell hyperplasia and collagen deposition induced by OVA. The increased ER stress-related proteins and altered epithelial-mesenchymal transition (EMT) markers were also inhibited by SYVN1 in vivo. Next, TGF-β1-induced bronchial epithelial cells (BEAS-2B) were used to induce EMT process in vitro. Results showed that TGF-β1 stimulation downregulated the expression of SYVN1, and SYVN1 overexpression prevented ER stress response and EMT process in TGF-β1-induced cells. In addition, we identified that SYVN1 bound to SIRT2 and promoted its ubiquitination and degradation. SIRT2 overexpression abrogated the protection of SYVN1 on ER stress and EMT in vitro.ConclusionsThese data suggest that SYVN1 suppresses ER stress through the ubiquitination and degradation of SIRT2 to block EMT process, thereby protecting against airway remodeling in asthma.

HFD-exacerbated Metabolic Side Effects of Olanzapine Are Suppressed by ER Stress Inhibitor.

Numerous schizophrenic patients are suffering from obesity primarily attributed to antipsychotic medication and poor dietary habits. This study investigated the progressive deterioration of olanzapine-induced metabolic disorders in the presence of a high-fat diet (HFD) and explored the involvement of endoplasmic reticulum (ER) stress. Female Sprague-Dawley rats fed on a standard chow diet or HFD were treated with olanzapine (3 mg/kg/day) and the ER stress inhibitor 4-phenylbutyric acid (4-PBA, 1 and 0.5 g/kg/day) for 8 days. Changes in body weight, food intake, and plasma lipids were assessed. Hepatic fat accumulation was evaluated using oil red O staining. Western blotting and immunofluorescence assays were employed to examine the expression of ER stress markers, NOD-like receptor pyrin domain-containing protein 3 (NLRP3), and proopiomelanocortin (POMC) in the hypothalamus or liver. Compared to olanzapine alone, olanzapine+HFD induced greater weight gain, increased hyperlipidemia, and enhanced hepatic fat accumulation (P<0.05). Co-treatment with 4-PBA exhibited a dose-dependent inhibition of these effects (P<0.05). Further mechanistic investigations revealed that olanzapine alone activated ER stress, upregulated NLRP3 expression in the hypothalamus and liver, and downregulated hypothalamic POMC expression. The HFD exacerbated these effects by 50%-100%. Moreover, co-administration of 4-PBA dose-dependently attenuated the olanzapine+HFD-induced alterations in ER stress, NLRP3, and POMC expression in the hypothalamus and liver (P<0.05). HFD worsened olanzapine-induced weight gain and lipid metabolic disorders, possibly through ER stress-POMC and ER stress-NLRP3 signaling. ER stress inhibitors could be effective in preventing olanzapine+HFD-induced metabolic disorders.

P53-Mediated Mitochondrial Translocation of EI24 Triggered by ER Stress Plays an Important Role in Arsenic-Induced Liver Damage via Activating Mitochondrial Apoptotic Pathway.

Chronic arsenic poisoning is a public health problem worldwide. In addition to skin lesions, the detrimental effect of arsenic poisoning on liver damage is one of the major issues. Our previous studies demonstrated that endoplasmic reticulum (ER) stress and p53 were associated with arsenic-induced liver damage. Literature has shown that EI24 is involved in hepatocyte hypertrophy; however, the underlying role and mechanism in arsenic-induced liver damage have not been fully elucidated. In this study, we explored the role of ER stress, p53, and EI24 as well as the regulatory relationship in arsenic poisoning populations and L-02 cells treated with distinct concentration NaAsO2 (2.5, 5, 10, and 20μM). Results showed that as with arsenic dose increment, expression levels of ER stress key proteins GRP78, ATF4, and CHOP were significantly enhanced. Additionally, p53 expression in nucleus, p53 phosphorylation at Ser15 and Ser1392, and p53 acetylation at lys382 were significantly increased in NaAsO2-treated L-02 cells. ER stress inhibitor 4-phenylbutyric acid (4-PBA) decreased the expression of p53 phosphorylation at Ser 392, p53 acetylation at lys382, and p53 expression in nucleus. Additionally, in 5μM NaAsO2 condition, p53 inhibitor pifithrin-α (PFT-α) aggravated 5μM NaAsO2-induced GRP78, ATF4, and CHOP expressions, cell apoptosis, and protein-SH consumption. But in 20μM NaAsO2 condition, PFT-α attenuated NaAsO2-induced cell apoptosis. Further results showed that 20μM NaAsO2 facilitated translocation of EI24 from ER to mitochondrion and interaction with VDAC2, leading to activate mitochondrial apoptotic pathway, but not observed in the 5-μM NaAsO2 group. Moreover, PFT-α and 4-PBA inhibited 20μM NaAsO2-induced EI24 expression in mitochondrion. Collectively, our results indicated that arsenic induced p53 activation via ER stress, under relatively low NaAsO2 concentration, NaAsO2-triggered p53 activation protected cells from apoptosis by alleviating ER stress. Another finding was that under relatively high NaAsO2 concentration, NaAsO2-activated p53 facilitated EI24 mitochondrial translocation and caused mitochondrial permeability increase, which represented a switch of p53 from a benefit role to pro-apoptosis function in NaAsO2-treated cells. The study contributed to in-depth understanding the mechanism of arsenic-induced liver damage and providing potential clues for following study.

Inhibition of ubiquitin specific peptidase 14 (USP14) promotes ER-phagy by inducing ER stress in human hepatoma HepG2 cells

ABSTRACT Autophagy plays a critical role in regulating the quality and quantity of cellular compartments; however, the mechanisms governing endoplasmic reticulum (ER) autophagy (ER-phagy) are still largely undefined. In this study, we identified several inhibitors of USP14, a ubiquitin-specific protease, including IU1 and b-AP15, as novel ER-phagy inducers through chemical library screening. While USP14 is known to act as an ER stress inducer, its precise role in ER-phagy remains unclear. Our findings demonstrate that treatment with either IU1 or b-AP15 induces ER-phagy by increasing ER stress in HepG2 cells. Similarly, depletion of USP14 augments ER-phagy and the ER stress response. The blockage of autophagy using an ULK1 inhibitor, SBI0206965, impedes ER-phagy. Moreover, inhibition of ER stress with tauroursodeoxycholic acid reverses ER-phagy by alleviating ER stress in HepG2 cells. We also found that suppression of the stress kinase JNK inhibited ER-phagy in IU1-treated cells. In conclusion, the results of this study suggest that the inhibition of USP14 accelerates ER-phagy by enhancing ER stress and JNK activation in HepG2 cells.

Homer1 Protects against Retinal Ganglion Cell Pyroptosis by Inhibiting Endoplasmic Reticulum Stress-Associated TXNIP/NLRP3 Inflammasome Activation after Middle Cerebral Artery Occlusion-Induced Retinal Ischemia.

Retinal ischemia, after cerebral ischemia, is an easily overlooked pathophysiological problem in which inflammation is considered to play an important role. Pyroptosis is a kind of cell death pattern accompanied by inflammation. Homer scaffold protein 1 (Homer1) has anti-inflammation properties and protects against ischemic injury. However, little is known about pyroptosis following middle cerebral artery occlusion (MCAO)-induced retinal ischemia and the regulatory mechanisms involved by Homer1 for the development of pyroptosis. In the present study, retinal ischemic injury was induced in mice by permanent MCAO in vivo, and retinal ganglion cells (RGCs) were subjected to Oxygen and Glucose Deprivation (OGD) to establish an in vitro model. It was shown that TXNIP/NLRP3-mediated pyroptosis was located predominantly in RGCs, which gradually increased after retinal ischemia and peaked at 24 h after retinal ischemia. Interestingly, the RGCs pyroptosis occurred not only in the cell body but also in the axon. Notably, the occurrence of pyroptosis coincided with the change of Homer1 expression in the retina after retinal ischemia and Homer1 also co-localized with RGCs. It was demonstrated that overexpression of Homer1 not only alleviated RGCs pyroptosis and inhibited the release of pro-inflammatory factors but also led to the increase in phosphorylation of AMPK, inhibition of ER stress, and preservation of visual function after retinal ischemia. In conclusion, it was suggested that Homer1 may protect against MCAO-induced retinal ischemia and RGCs pyroptosis by inhibiting endoplasmic reticulum stress-associated TXNIP/NLRP3 inflammasome activation after MCAO-induced retinal ischemia.