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Sample records for reticulum stress regulators

  1. Endoplasmic Reticulum Stress Regulates Adipocyte Resistin Expression

    PubMed Central

    Lefterova, Martina I.; Mullican, Shannon E.; Tomaru, Takuya; Qatanani, Mohammed; Schupp, Michael; Lazar, Mitchell A.

    2009-01-01

    OBJECTIVE Resistin is a secreted polypeptide that impairs glucose metabolism and, in rodents, is derived exclusively from adipocytes. In murine obesity, resistin circulates at elevated levels but its gene expression in adipose tissue is paradoxically reduced. The mechanism behind the downregulation of resistin mRNA is poorly understood. We investigated whether endoplasmic reticulum (ER) stress, which is characteristic of obese adipose tissue, regulates resistin expression in cultured mouse adipocytes. RESEARCH DESIGN AND METHODS The effects of endoplasmic stress inducers on resistin mRNA and secreted protein levels were examined in differentiated 3T3-L1 adipocytes, focusing on the expression and genomic binding of transcriptional regulators of resistin. The association between downregulated resistin mRNA and induction of ER stress was also investigated in the adipose tissue of mice fed a high-fat diet. RESULTS ER stress reduced resistin mRNA in 3T3-L1 adipocytes in a time- and dose-dependent manner. The effects of ER stress were transcriptional because of downregulation of CAAT/enhancer binding protein-α and peroxisome proliferator–activated receptor-γ transcriptional activators and upregulation of the transcriptional repressor CAAT/enhancer binding protein homologous protein-10 (CHOP10). Resistin protein was also substantially downregulated, showing a close correspondence with mRNA levels in 3T3-L1 adipocytes as well as in the fat pads of obese mice. CONCLUSIONS ER stress is a potent regulator of resistin, suggesting that ER stress may underlie the local downregulation of resistin mRNA and protein in fat in murine obesity. The paradoxical increase in plasma may be because of various systemic abnormalities associated with obesity and insulin resistance. PMID:19491212

  2. Endoplasmic reticulum: ER stress regulates mitochondrial bioenergetics

    PubMed Central

    Bravo, Roberto; Gutierrez, Tomás; Paredes, Felipe; Gatica, Damián; Rodriguez, Andrea E.; Pedrozo, Zully; Chiong, Mario; Parra, Valentina; Quest, Andrew F.G.; Rothermel, Beverly A.; Lavandero, Sergio

    2014-01-01

    Endoplasmic reticulum (ER) stress activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. The molecular mechanisms responsible for execution of the cell death program are relatively well characterized, but the metabolic events taking place during the adaptive phase of ER stress remain largely undefined. Here we discuss emerging evidence regarding the metabolic changes that occur during the onset of ER stress and how ER influences mitochondrial function through mechanisms involving calcium transfer, thereby facilitating cellular adaptation. Finally, we highlight how dysregulation of ER–mitochondrial calcium homeostasis during prolonged ER stress is emerging as a novel mechanism implicated in the onset of metabolic disorders. PMID:22064245

  3. Endoplasmic reticulum stress regulates rat mandibular cartilage thinning under compressive mechanical stress.

    PubMed

    Li, Huang; Zhang, Xiang-Yu; Wu, Tuo-Jiang; Cheng, Wei; Liu, Xin; Jiang, Ting-Ting; Wen, Juan; Li, Jie; Ma, Qiao-Ling; Hua, Zi-Chun

    2013-06-21

    Compressive mechanical stress-induced cartilage thinning has been characterized as a key step in the progression of temporomandibular joint diseases, such as osteoarthritis. However, the regulatory mechanisms underlying this loss have not been thoroughly studied. Here, we used an established animal model for loading compressive mechanical stress to induce cartilage thinning in vivo. The mechanically stressed mandibular chondrocytes were then isolated to screen potential candidates using a proteomics approach. A total of 28 proteins were identified that were directly or indirectly associated with endoplasmic reticulum stress, including protein disulfide-isomerase, calreticulin, translationally controlled tumor protein, and peptidyl-prolyl cis/trans-isomerase protein. The altered expression of these candidates was validated at both the mRNA and protein levels. The induction of endoplasmic reticulum stress by mechanical stress loading was confirmed by the activation of endoplasmic reticulum stress markers, the elevation of the cytoplasmic Ca(2+) level, and the expansion of endoplasmic reticulum membranes. More importantly, the use of a selective inhibitor to block endoplasmic reticulum stress in vivo reduced the apoptosis observed at the early stages of mechanical stress loading and inhibited the proliferation observed at the later stages of mechanical stress loading. Accordingly, the use of the inhibitor significantly restored cartilage thinning. Taken together, these results demonstrated that endoplasmic reticulum stress is significantly activated in mechanical stress-induced mandibular cartilage thinning and, more importantly, that endoplasmic reticulum stress inhibition alleviates this loss, suggesting a novel pharmaceutical strategy for the treatment of mechanical stress-induced temporomandibular joint diseases.

  4. Drosophila melanogaster activating transcription factor 4 regulates glycolysis during endoplasmic reticulum stress.

    PubMed

    Lee, Ji Eun; Oney, McKenna; Frizzell, Kimberly; Phadnis, Nitin; Hollien, Julie

    2015-02-13

    Endoplasmic reticulum (ER) stress results from an imbalance between the load of proteins entering the secretory pathway and the ability of the ER to fold and process them. The response to ER stress is mediated by a collection of signaling pathways termed the unfolded protein response, which plays important roles in development and disease. Here we show that in Drosophila melanogaster S2 cells, ER stress induces a coordinated change in the expression of genes involved in carbon metabolism. Genes encoding enzymes that carry out glycolysis were up-regulated, whereas genes encoding proteins in the tricarboxylic acid cycle and respiratory chain complexes were down-regulated. The unfolded protein response transcription factor Atf4 was necessary for the up-regulation of glycolytic enzymes and Lactate dehydrogenase (Ldh). Furthermore, Atf4 binding motifs in promoters for these genes could partially account for their regulation during ER stress. Finally, flies up-regulated Ldh and produced more lactate when subjected to ER stress. Together, these results suggest that Atf4 mediates a shift from a metabolism based on oxidative phosphorylation to one more heavily reliant on glycolysis, reminiscent of aerobic glycolysis or the Warburg effect observed in cancer and other proliferative cells.

  5. Lyn kinase represses mucus hypersecretion by regulating IL-13-induced endoplasmic reticulum stress in asthma.

    PubMed

    Wang, Xing; Yang, Xiaoqiong; Li, Yin; Wang, Xiaoyun; Zhang, Yun; Dai, Xi; Niu, Bin; Wu, Juan; Yuan, Xiefang; Xiong, Anjie; Liu, Zhigang; Zhong, Nanshan; Wu, Min; Li, Guoping

    2017-02-01

    In asthma, mucus hypersecretion is thought to be a prominent pathological feature associated with widespread mucus plugging. However, the current treatments for mucus hypersecretion are often ineffective or temporary. The potential therapeutic targets of mucus hypersecretion in asthma remain unknown. Here, we show that Lyn is a central effector of endoplasmic reticulum stress (ER stress) and mucous hypersecretion in asthma. In Lyn-transgenic mice (Lyn-TG) and wild-type (WT) C57BL/6J mice exposed to ovalbumin (OVA), Lyn overexpression attenuates mucus hypersecretion and ER stress. Interleukin 13 (IL-13) induced MUC5AC expression by enhancing ER stress in vitro. Lyn serves as a negative regulator of IL-13-induced ER stress and MUC5AC expression. We further find that an inhibitor of ER stress, which is likely involved in the PI3K p85α/Akt pathway and NFκB activity, blocked MUC5AC expression in Lyn-knockdown cells. Furthermore, PI3K/Akt signaling is required for IL-13-induced ER stress and MUC5AC expression in airway epithelial cells. The ER stress regulation of MUC5AC expression depends on NFκB in Lyn-knockdown airway epithelial cells. Our studies indicate not only a concept of mucus hypersecretion in asthma that involves Lyn kinase but also an important therapeutic candidate for asthma.

  6. Sphingosine-1-phosphate Phosphatase 2 Regulates Pancreatic Islet β-Cell Endoplasmic Reticulum Stress and Proliferation.

    PubMed

    Taguchi, Yoshimitsu; Allende, Maria L; Mizukami, Hiroki; Cook, Emily K; Gavrilova, Oksana; Tuymetova, Galina; Clarke, Benjamin A; Chen, Weiping; Olivera, Ana; Proia, Richard L

    2016-06-03

    Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite that regulates basic cell functions through metabolic and signaling pathways. Intracellular metabolism of S1P is controlled, in part, by two homologous S1P phosphatases (SPPases), 1 and 2, which are encoded by the Sgpp1 and Sgpp2 genes, respectively. SPPase activity is needed for efficient recycling of sphingosine into the sphingolipid synthesis pathway. SPPase 1 is important for skin homeostasis, but little is known about the functional role of SPPase 2. To identify the functions of SPPase 2 in vivo, we studied mice with the Sgpp2 gene deleted. In contrast to Sgpp1(-/-) mice, Sgpp2(-/-) mice had normal skin and were viable into adulthood. Unexpectedly, WT mice expressed Sgpp2 mRNA at high levels in pancreatic islets when compared with other tissues. Sgpp2(-/-) mice had normal pancreatic islet size; however, they exhibited defective adaptive β-cell proliferation that was demonstrated after treatment with either a high-fat diet or the β-cell-specific toxin, streptozotocin. Importantly, β-cells from untreated Sgpp2(-/-) mice showed significantly increased expression of proteins characteristic of the endoplasmic reticulum stress response compared with β-cells from WT mice, indicating a basal islet defect. Our results show that Sgpp2 deletion causes β-cell endoplasmic reticulum stress, which is a known cause of β-cell dysfunction, and reveal a juncture in the sphingolipid recycling pathway that could impact the development of diabetes.

  7. Identification of a Novel Endoplasmic Reticulum Stress Response Element Regulated by XBP1*

    PubMed Central

    Misiewicz, Michael; Déry, Marc-André; Foveau, Bénédicte; Jodoin, Julie; Ruths, Derek; LeBlanc, Andréa C.

    2013-01-01

    Understanding the regulatory mechanisms mediating PRNP gene expression is highly relevant to elucidating normal cellular prion protein (PrP) function(s) and the transmissibility of prion protein neurodegenerative diseases. Here, luciferase reporter assays showed that an endoplasmic reticulum stress element (ERSE)-like element, CCAAT-N26-CCACG in the human PRNP promoter, is regulated by ER stress and X-box-binding protein 1 (XBP1) but not by activating transcription factor 6 α (ATF6α). Bioinformatics identified the ERSE-26 motif in 37 other human genes in the absence of canonical ERSE sites except for three genes. Several of these genes are associated with a synaptic function or are involved in oxidative stress. Brefeldin A, tunicamycin, and thapsigargin ER stressors induced gene expression of PRNP and four randomly chosen ERSE-26-containing genes, ERLEC1, GADD45B, SESN2, and SLC38A5, in primary human neuron cultures or in the breast carcinoma MCF-7 cell line, although the level of the response depends on the gene analyzed, the genetic background of the cells, the cell type, and the ER stressor. Overexpression of XBP1 increased, whereas siRNA knockdown of XBP1 considerably reduced, PRNP and ERLEC1 mRNA levels in MCF-7 cells. Taken together, these results identify a novel ER stress regulator, which implicates the ER stress response in previously unrecognized cellular functions. PMID:23737521

  8. Regulation of mitochondrial function and endoplasmic reticulum stress by nitric oxide in pluripotent stem cells

    PubMed Central

    Caballano-Infantes, Estefania; Terron-Bautista, José; Beltrán-Povea, Amparo; Cahuana, Gladys M; Soria, Bernat; Nabil, Hajji; Bedoya, Francisco J; Tejedo, Juan R

    2017-01-01

    Mitochondrial dysfunction and endoplasmic reticulum stress (ERS) are global processes that are interrelated and regulated by several stress factors. Nitric oxide (NO) is a multifunctional biomolecule with many varieties of physiological and pathological functions, such as the regulation of cytochrome c inhibition and activation of the immune response, ERS and DNA damage; these actions are dose-dependent. It has been reported that in embryonic stem cells, NO has a dual role, controlling differentiation, survival and pluripotency, but the molecular mechanisms by which it modulates these functions are not yet known. Low levels of NO maintain pluripotency and induce mitochondrial biogenesis. It is well established that NO disrupts the mitochondrial respiratory chain and causes changes in mitochondrial Ca2+ flux that induce ERS. Thus, at high concentrations, NO becomes a potential differentiation agent due to the relationship between ERS and the unfolded protein response in many differentiated cell lines. Nevertheless, many studies have demonstrated the need for physiological levels of NO for a proper ERS response. In this review, we stress the importance of the relationships between NO levels, ERS and mitochondrial dysfunction that control stem cell fate as a new approach to possible cell therapy strategies. PMID:28289506

  9. Endoplasmic reticulum stress regulates inflammation and insulin resistance in skeletal muscle from pregnant women.

    PubMed

    Liong, Stella; Lappas, Martha

    2016-04-15

    Sterile inflammation and infection are key mediators of inflammation and peripheral insulin resistance associated with gestational diabetes mellitus (GDM). Studies have shown endoplasmic reticulum (ER) stress to induce inflammation and insulin resistance associated with obesity and type 2 diabetes, however is paucity of studies investigating the effects of ER stress in skeletal muscle on inflammation and insulin resistance associated with GDM. ER stress proteins IRE1α, GRP78 and XBP-1s were upregulated in skeletal muscle of obese pregnant women, whereas IRE1α was increased in GDM women. Suppression of ER stress, using ER stress inhibitor tauroursodeoxycholic acid (TUDCA) or siRNA knockdown of IRE1α and GRP78, significantly downregulated LPS-, poly(I:C)- or IL-1β-induced production of IL-6, IL-8, IL-1β and MCP-1. Furthermore, LPS-, poly(I:C)- or TNF-α-induced insulin resistance was improved following suppression of ER stress, by increasing insulin-stimulated phosphorylation of IR-β, IRS-1, GLUT-4 expression and glucose uptake. In summary, our inducible obesity and GDM-like models suggests that the development of GDM may be involved in activating ER stress-induced inflammation and insulin resistance in human skeletal muscle.

  10. Endoplasmic reticulum stress-regulated CXCR3 pathway mediates inflammation and neuronal injury in acute glaucoma.

    PubMed

    Ha, Y; Liu, H; Xu, Z; Yokota, H; Narayanan, S P; Lemtalsi, T; Smith, S B; Caldwell, R W; Caldwell, R B; Zhang, W

    2015-10-08

    Acute glaucoma is a leading cause of irreversible blindness in East Asia. The mechanisms underlying retinal neuronal injury induced by a sudden rise in intraocular pressure (IOP) remain obscure. Here we demonstrate that the activation of CXCL10/CXCR3 axis, which mediates the recruitment and activation of inflammatory cells, has a critical role in a mouse model of acute glaucoma. The mRNA and protein expression levels of CXCL10 and CXCR3 were significantly increased after IOP-induced retinal ischemia. Blockade of the CXCR3 pathway by deleting CXCR3 gene significantly attenuated ischemic injury-induced upregulation of inflammatory molecules (interleukin-1β and E-selectin), inhibited the recruitment of microglia/monocyte to the superficial retina, reduced peroxynitrite formation, and prevented the loss of neurons within the ganglion cell layer. In contrast, intravitreal delivery of CXCL10 increased leukocyte recruitment and retinal cell apoptosis. Inhibition of endoplasmic reticulum (ER) stress with chemical chaperones partially blocked ischemic injury-induced CXCL10 upregulation, whereas induction of ER stress with tunicamycin enhanced CXCL10 expression in retina and primary retinal ganglion cells. Interestingly, deleting CXCR3 attenuated ER stress-induced retinal cell death. In conclusion, these results indicate that ER stress-medicated activation of CXCL10/CXCR3 pathway has an important role in retinal inflammation and neuronal injury after high IOP-induced ischemia.

  11. RIPK1 regulates survival of human melanoma cells upon endoplasmic reticulum stress through autophagy.

    PubMed

    Luan, Qi; Jin, Lei; Jiang, Chen Chen; Tay, Kwang Hong; Lai, Fritz; Liu, Xiao Ying; Liu, Yi Lun; Guo, Su Tang; Li, Chun Ying; Yan, Xu Guang; Tseng, Hsin-Yi; Zhang, Xu Dong

    2015-01-01

    Although RIPK1 (receptor [TNFRSF]-interacting protein kinase 1) is emerging as a critical determinant of cell fate in response to cellular stress resulting from activation of death receptors and DNA damage, its potential role in cell response to endoplasmic reticulum (ER) stress remains undefined. Here we report that RIPK1 functions as an important prosurvival mechanism in melanoma cells undergoing pharmacological ER stress induced by tunicamycin (TM) or thapsigargin (TG) through activation of autophagy. While treatment with TM or TG upregulated RIPK1 and triggered autophagy in melanoma cells, knockdown of RIPK1 inhibited autophagy and rendered the cells sensitive to killing by TM or TG, recapitulating the effect of inhibition of autophagy. Consistently, overexpression of RIPK1 enhanced induction of autophagy and conferred resistance of melanoma cells to TM- or TG-induced cell death. Activation of MAPK8/JNK1 or MAPK9/JNK2, which phosphorylated BCL2L11/BIM leading to its dissociation from BECN1/Beclin 1, was involved in TM- or TG-induced, RIPK1-mediated activation of autophagy; whereas, activation of the transcription factor HSF1 (heat shock factor protein 1) downstream of the ERN1/IRE1-XBP1 axis of the unfolded protein response was responsible for the increase in RIPK1 in melanoma cells undergoing pharmacological ER stress. Collectively, these results identify upregulation of RIPK1 as an important resistance mechanism of melanoma cells to TM- or TG-induced ER stress by protecting against cell death through activation of autophagy, and suggest that targeting the autophagy-activating mechanism of RIPK1 may be a useful strategy to enhance sensitivity of melanoma cells to therapeutic agents that induce ER stress.

  12. The obesity-induced transcriptional regulator TRIP-Br2 mediates visceral fat endoplasmic reticulum stress-induced inflammation

    PubMed Central

    Qiang, Guifen; Kong, Hyerim Whang; Fang, Difeng; McCann, Maximilian; Yang, Xiuying; Du, Guanhua; Blüher, Matthias; Zhu, Jinfang; Liew, Chong Wee

    2016-01-01

    The intimate link between location of fat accumulation and metabolic disease risk and depot-specific differences is well established, but how these differences between depots are regulated at the molecular level remains largely unclear. Here we show that TRIP-Br2 mediates endoplasmic reticulum (ER) stress-induced inflammatory responses in visceral fat. Using in vitro, ex vivo and in vivo approaches, we demonstrate that obesity-induced circulating factors upregulate TRIP-Br2 specifically in visceral fat via the ER stress pathway. We find that ablation of TRIP-Br2 ameliorates both chemical and physiological ER stress-induced inflammatory and acute phase response in adipocytes, leading to lower circulating levels of inflammatory cytokines. Using promoter assays, as well as molecular and pharmacological experiments, we show that the transcription factor GATA3 is responsible for the ER stress-induced TRIP-Br2 expression in visceral fat. Taken together, our study identifies molecular regulators of inflammatory response in visceral fat that—given that these pathways are conserved in humans—might serve as potential therapeutic targets in obesity. PMID:27109496

  13. Folate Protects Hepatocytes of Hyperhomocysteinemia Mice from Apoptosis via Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)-activated Endoplasmic Reticulum Stress.

    PubMed

    Yang, Anning; Sun, Yue; Mao, Caiyan; Yang, Songhao; Huang, Min; Deng, Mei; Ding, Ning; Yang, Xiaoling; Zhang, Minghao; Jin, Shaoju; Jiang, Yideng; Huang, Ying

    2017-02-23

    Folate deficiency is a known risk factor for liver injury; however, the underlying mechanism remains unclear. In this study, we employed a high homocysteine-induced liver injury model of Apolipoprotein E-deficient (ApoE(-/-) ) mice fed high-methionine diet and found that high homocysteine induced endoplasmic reticulum (ER) stress and liver cell apoptosis by downregulation of cystic fibrosis transmembrane conductance regulator (CFTR) expression; observations that were attenuated with supplementation of dietary folate. The regulation on CFTR expression was mediated by CFTR promoter methylation and trimethylation of lysine 27 on histone H3 (H3K27me3). Mechanistically, folate inhibited homocysteine-induced CFTR promoter methylation and H3K27me3, which resulted in upregulation of CFTR expression, and reduced ER stress and liver cell apoptosis. Further study showed that folate inhibited the expression of DNA methyltransferase 1 and enhancer of zeste homolog 2, downregulated the cellular concentrations of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) and upregulated the SAM/SAH ratio, leading to the inhibition of Hcy-induced DNA hypermethylation and H3K27me3 in CFTR promoter. In conclusion, our results provide insight into the protective role of folate in homocysteine-induced ER stress and liver cell apoptosis through the regulation of CFTR expression. This article is protected by copyright. All rights reserved.

  14. Transcription Factor CREB3L1 Regulates Endoplasmic Reticulum Stress Response Genes in the Osmotically Challenged Rat Hypothalamus

    PubMed Central

    Greenwood, Mingkwan; Greenwood, Michael Paul; Paton, Julian F. R.; Murphy, David

    2015-01-01

    Arginine vasopressin (AVP) is synthesised in magnocellular neurons (MCNs) of supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus. In response to the hyperosmotic stressors of dehydration (complete fluid deprivation, DH) or salt loading (drinking 2% salt solution, SL), AVP synthesis increases in MCNs, which over-burdens the protein folding machinery in the endoplasmic reticulum (ER). ER stress and the unfolded protein response (UPR) are signaling pathways that improve ER function in response to the accumulation of misfold/unfold protein. We asked whether an ER stress response was activated in the SON and PVN of DH and SL rats. We observed increased mRNA expression for the immunoglobulin heavy chain binding protein (BiP), activating transcription factor 4 (Atf4), C/EBP-homologous protein (Chop), and cAMP responsive element binding protein 3 like 1 (Creb3l1) in both SON and PVN of DH and SL rats. Although we found no changes in the splicing pattern of X box-binding protein 1 (Xbp1), an increase in the level of the unspliced form of Xbp1 (Xbp1U) was observed in DH and SL rats. CREB3L1, a novel ER stress inducer, has been shown to be activated by ER stress to regulate the expression of target genes. We have previously shown that CREB3L1 is a transcriptional regulator of the AVP gene; however, a role for CREB3L1 in the response to ER stress has yet to be investigated in MCNs. Here, we used lentiviral vectors to introduce a dominant negative form of CREB3L1 (CREB3L1DN) in the rat SON. Expression of CREB3L1DN in the SON decreased Chop and Xbp1U mRNA levels, but not BiP and Atf4 transcript expression. CREB3L1 is thus implicated as a transcriptional mediator of the ER stress response in the osmotically stimulated SON. PMID:25915053

  15. Endoplasmic Reticulum Stress and Ethanol Neurotoxicity.

    PubMed

    Yang, Fanmuyi; Luo, Jia

    2015-10-14

    Ethanol abuse affects virtually all organ systems and the central nervous system (CNS) is particularly vulnerable to excessive ethanol exposure. Ethanol exposure causes profound damages to both the adult and developing brain. Prenatal ethanol exposure induces fetal alcohol spectrum disorders (FASD) which is associated with mental retardation and other behavioral deficits. A number of potential mechanisms have been proposed for ethanol-induced brain damage; these include the promotion of neuroinflammation, interference with signaling by neurotrophic factors, induction of oxidative stress, modulation of retinoid acid signaling, and thiamine deficiency. The endoplasmic reticulum (ER) regulates posttranslational protein processing and transport. The accumulation of unfolded or misfolded proteins in the ER lumen triggers ER stress and induces unfolded protein response (UPR) which are mediated by three transmembrane ER signaling proteins: pancreatic endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), and activating transcription factor 6 (ATF6). UPR is initiated to protect cells from overwhelming ER protein loading. However, sustained ER stress may result in cell death. ER stress has been implied in various CNS injuries, including brain ischemia, traumatic brain injury, and aging-associated neurodegeneration, such as Alzheimer's disease (AD), Huntington's disease (HD), Amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). However, effects of ethanol on ER stress in the CNS receive less attention. In this review, we discuss recent progress in the study of ER stress in ethanol-induced neurotoxicity. We also examine the potential mechanisms underlying ethanol-mediated ER stress and the interaction among ER stress, oxidative stress and autophagy in the context of ethanol neurotoxicity.

  16. PLIN2 is a Key Regulator of the Unfolded Protein Response and Endoplasmic Reticulum Stress Resolution in Pancreatic β Cells

    PubMed Central

    Chen, Elaine; Tsai, Tsung Huang; Li, Lan; Saha, Pradip; Chan, Lawrence; Chang, Benny Hung-Junn

    2017-01-01

    Progressive pancreatic β cell failure underlies the transition of impaired glucose tolerance to overt diabetes; endoplasmic reticulum (ER) stress expedites β cell failure in this situation. ER stress can be elicited by lipotoxicity and an increased demand for insulin in diabetes. We previously reported that the lipid droplet protein perilipin 2 (PLIN2) modulates lipid homeostasis in the liver. Here, we show that PLIN2 modulates the unfolded protein response (UPR) and ER stress in pancreatic β cells. PLIN2 expression goes up when β cells are exposed to a lipid load or to chemical ER stress inducers. Downregulation of PLIN2 ameliorates the effects of fatty acid- and chemical-induced ER stress, whereas PLIN2 overexpression exacerbates them. Diabetic Akita mice, which carry a heterozygous C96Y Ins2 mutation, exhibit elevated PLIN2 expression and ER stress in their β cells. Genetic ablation of Plin2 in Akita mice leads to mitigation of ER stress, forestalling β cell apoptosis, partially restoring β cell mass, and ameliorating diabetes. Mechanistic experiments showed that PLIN2 downregulation is associated with enhanced autophagic flux and accelerated ER stress resolution. In sum, we have identified a crucial role for PLIN2 in modulating autophagy, ER stress resolution, and β cell apoptosis and survival. PMID:28102311

  17. Selenoprotein R Protects Human Lens Epithelial Cells against D-Galactose-Induced Apoptosis by Regulating Oxidative Stress and Endoplasmic Reticulum Stress.

    PubMed

    Dai, Jie; Liu, Hongmei; Zhou, Jun; Huang, Kaixun

    2016-02-10

    Selenium is an essential micronutrient for humans. Much of selenium's beneficial influence on health is attributed to its presence within 25 selenoproteins. Selenoprotein R (SelR), known as methionine sulfoxide reductase B1 (MsrB1), is a selenium-dependent enzyme that, like other Msrs, is required for lens cell viability. In order to investigate the roles of SelR in protecting human lens epithelial (hLE) cells against damage, the influences of SelR gene knockdown on d-galactose-induced apoptosis in hLE cells were studied. The results showed that both d-galactose and SelR gene knockdown by siRNA independently induced oxidative stress. When SelR-gene-silenced hLE cells were exposed to d-galactose, glucose-regulated protein 78 (GRP78) protein level was further increased, mitochondrial membrane potential was significantly decreased and accompanied by a release of mitochondrial cytochrome c. At the same time, the apoptosis cells percentage and the caspase-3 activity were visibly elevated in hLE cells. These results suggested that SelR might protect hLE cell mitochondria and mitigating apoptosis in hLE cells against oxidative stress and endoplasmic reticulum (ER) stress induced by d-galactose, implying that selenium as a micronutrient may play important roles in hLE cells.

  18. Selenoprotein R Protects Human Lens Epithelial Cells against d-Galactose-Induced Apoptosis by Regulating Oxidative Stress and Endoplasmic Reticulum Stress

    PubMed Central

    Dai, Jie; Liu, Hongmei; Zhou, Jun; Huang, Kaixun

    2016-01-01

    Selenium is an essential micronutrient for humans. Much of selenium’s beneficial influence on health is attributed to its presence within 25 selenoproteins. Selenoprotein R (SelR), known as methionine sulfoxide reductase B1 (MsrB1), is a selenium-dependent enzyme that, like other Msrs, is required for lens cell viability. In order to investigate the roles of SelR in protecting human lens epithelial (hLE) cells against damage, the influences of SelR gene knockdown on d-galactose-induced apoptosis in hLE cells were studied. The results showed that both d-galactose and SelR gene knockdown by siRNA independently induced oxidative stress. When SelR-gene-silenced hLE cells were exposed to d-galactose, glucose-regulated protein 78 (GRP78) protein level was further increased, mitochondrial membrane potential was significantly decreased and accompanied by a release of mitochondrial cytochrome c. At the same time, the apoptosis cells percentage and the caspase-3 activity were visibly elevated in hLE cells. These results suggested that SelR might protect hLE cell mitochondria and mitigating apoptosis in hLE cells against oxidative stress and endoplasmic reticulum (ER) stress induced by d-galactose, implying that selenium as a micronutrient may play important roles in hLE cells. PMID:26875981

  19. Albumin overload down-regulates integrin-β1 through reactive oxygen species-endoplasmic reticulum stress pathway in podocytes.

    PubMed

    Cheng, Yu-Chi; Chen, Chien-An; Chang, Jer-Ming; Chen, Hung-Chun

    2015-08-01

    Proteinuria is a major hallmark of glomerular nephropathy and endoplasmic reticulum (ER) stress plays an important role in glomerular nephropathy. The protein levels of integrin-β1 in podocytes are found to be negative correlation with amount of proteinuria. This study investigated whether urinary protein, particularly albumin, induced ER stress that consequently reduced integrin-β1 expression. All experiments were performed using primary cultured rat podocyte. Protein and mRNA expression were measured by western blotting and semiquantified reverse transcriptase polymerase chain reaction. Albumin uptake was found at 1 h after albumin addition. Albumin reduced precursor and mature forms of integrin-β1, but did not change mRNA levels of integrin-β1. Albumin induced reactive oxygen species (ROS) generation and ER stress. Antioxidant (N-acetylcysteine) suppressed albumin-induced ER stress and decrements in precursor and mature forms of integrin-β1. Then, ER stress inhibitors (4-phenylbutyrate and salubrinal) also inhibited albumin-induced decrements in precursor and mature forms of integrin-β1. The potent ER stress inducers (thapsigargin and tunicamycin) directly decreased precursor and mature forms of integrin-β1 and led appearance of unglycosylated core protein of integrin-β1. Our results show that in proteinuric disease, albumin decreases precursor and mature forms of integrin-β1 through ROS-ER stress pathway in podocytes.

  20. PACE4 regulates apoptosis in human prostate cancer cells via endoplasmic reticulum stress and mitochondrial signaling pathways

    PubMed Central

    Yao, Zhiyong; Sun, Bin; Hong, Quan; Yan, Jingmin; Mu, Dawei; Li, Jianye; Sheng, Haibo; Guo, Heqing

    2015-01-01

    Background PACE4 is a proprotein convertase capable of processing numerous substrates involved in tumor growth, invasion, and metastasis. However, the precise role of PACE4 during prostate cancer cell apoptosis has not been reported. Methods In the present study, human prostate cancer cell lines DU145, LNCaP, and PC3 were transfected with PACE4 small interfering (si)RNA to investigate the underlying mechanisms of apoptosis. Results We revealed that PACE4 siRNA exhibited antitumor activity by inducing apoptosis, as determined by Cell Counting Kit-8 (CCK-8), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltet-razolium bromide (MTT) assay, cell cycle analysis, Hoechst staining, caspase-3/7 activity, and western blot analysis. In addition, PACE4 siRNA significantly increased the ratio of Bax/Bcl-2, which led to the release of cytochrome c. Moreover, PACE4 siRNA also induced endoplasmic reticulum stress by increasing the expression of GRP78, GRP94, p-PERK, and p-eIF2α. The ratio of Bax/Bcl-2 and GRP78 were also increased in PACE4 gene knockdown prostate cancer cells compared with the control cells. Conclusion These data demonstrate that PACE4 siRNA may exert its antitumor activity through mitochondrial and endoplasmic reticulum stress signaling pathways, indicating it may be a novel therapeutic target for prostate cancer. PMID:26604689

  1. Membrane hyperpolarization induced by endoplasmic reticulum stress facilitates ca(2+) influx to regulate cell cycle progression in brain capillary endothelial cells.

    PubMed

    Kito, Hiroaki; Yamamura, Hisao; Suzuki, Yoshiaki; Ohya, Susumu; Asai, Kiyofumi; Imaizumi, Yuji

    2014-01-01

    Upregulation of the Kir2.1 channel during endoplasmic reticulum (ER) stress in t-BBEC117, an immortalized bovine brain endothelial cell line, caused a sustained increase in intracellular Ca(2+) concentration ([Ca(2+)]i) and a facilitation of cell death. Expressions of Ca(2+) influx channels (TRPC, Orai1, STIM1) were unchanged by ER stress. The ER stress-induced [Ca(2+)]i increase was mainly attributed to the deeper resting membrane potential due to Kir2.1 upregulation. ER stress arrested at the G2/M phase and it was attenuated by an inhibitor of Kir2.1. These results indicate that Kir2.1 upregulation by ER stress facilitates cell death via regulation of cell cycle progression in t-BBEC117.

  2. SIRT1 attenuates palmitate-induced endoplasmic reticulum stress and insulin resistance in HepG2 cells via induction of oxygen-regulated protein 150

    USGS Publications Warehouse

    Jung, T.W.; Lee, K.T.; Lee, M.W.; Ka, K.H.

    2012-01-01

    Endoplasmic reticulum (ER) stress has been implicated in the pathology of type 2 diabetes mellitus (T2DM). Although SIRT1 has a therapeutic effect on T2DM, the mechanisms by which SIRT1 ameliorates insulin resistance (IR) remain unclear. In this study, we investigated the impact of SIRT1 on palmitate-induced ER stress in HepG2 cells and its underlying signal pathway. Treatment with resveratrol, a SIRT1 activator significantly inhibited palmitate-induced ER stress, leading to the protection against palmitate-induced ER stress and insulin resistance. Resveratrol and SIRT1 overexpression induced the expression of oxygen-regulated protein (ORP) 150 in HepG2 cells. Forkhead box O1 (FOXO1) was involved in the regulation of ORP150 expression because suppression of FOXO1 inhibited the induction of ORP150 by SIRT1. Our results indicate a novel mechanism by which SIRT1 regulates ER stress by overexpression of ORP150, and suggest that SIRT1 ameliorates palmitate-induced insulin resistance in HepG2 cells via regulation of ER stress.

  3. Regulation of calnexin sub-cellular localization modulates endoplasmic reticulum stress-induced apoptosis in MCF-7 cells.

    PubMed

    Delom, Frédéric; Fessart, Delphine; Chevet, Eric

    2007-02-01

    The endoplasmic reticulum (ER) is the cellular compartment where proteins enter the secretory pathway, undergo post-translational modifications and acquire a correct conformation. If these functions are chronically altered, specific ER stress signals are triggered to promote cell death through the intrinsic apoptotic pathway. Here, we show that tunicamycin causes significant alteration of calnexin sub-cellular distribution in MCF-7 cells. Interestingly, this correlates with the absence of both tunicamycin-induced calnexin phosphorylation as well as tunicamycin-induced cell death. Under these conditions, calnexin-associated Bap31, an ER integral membrane protein, is subjected to a caspase-8 cleavage pattern within a specific sub-compartment of the ER. These results suggest that MCF-7 resistance to ER stress-induced apoptosis is partially mediated by the expression level of calnexin which in turn controls its sub-cellular localization, and its association with Bap31. These data may delineate a resistance mechanism to the ER stress-induced intrinsic apoptotic pathway.

  4. Icariin displays anticancer activity against human esophageal cancer cells via regulating endoplasmic reticulum stress-mediated apoptotic signaling

    PubMed Central

    Fan, Chongxi; Yang, Yang; Liu, Yong; Jiang, Shuai; Di, Shouyin; Hu, Wei; Ma, Zhiqiang; Li, Tian; Zhu, Yifang; Xin, Zhenlong; Wu, Guiling; Han, Jing; Li, Xiaofei; Yan, Xiaolong

    2016-01-01

    In this study, we investigated the antitumor activity of icariin (ICA) in human esophageal squamous cell carcinoma (ESCC) in vitro and in vivo and explored the role of endoplasmic reticulum stress (ERS) signaling in this activity. ICA treatment resulted in a dose- and time-dependent decrease in the viability of human EC109 and TE1 ESCCs. Additionally, ICA exhibited strong antitumor activity, as evidenced by reductions in cell migration, adhesion, and intracellular glutathione (GSH) levels and by increases in the EC109 and TE1 cell apoptotic index, Caspase 9 activity, reactive oxygen species (ROS) level, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Furthermore, ICA treatments upregulated the levels of ERS-related molecules (p-PERK, GRP78, ATF4, p-eIF2α, and CHOP) and a pro-apoptotic protein (PUMA) and simultaneously downregulated an anti-apoptotic protein (Bcl2) in the two ESCC cell lines. The downregulation of ERS signaling using eIF2α siRNA desensitized EC109 and TE1 cells to ICA treatment, and the upregulation of ERS signaling using thapsigargin sensitized EC109 and TE1 cells to ICA treatment. In summary, ERS activation may represent a mechanism of action for the anticancer activity of ICA in ESCCs, and the activation of ERS signaling may represent a novel therapeutic intervention for human esophageal cancer. PMID:26892033

  5. A Molecular Web: Endoplasmic Reticulum Stress, Inflammation, and Oxidative Stress

    PubMed Central

    Chaudhari, Namrata; Talwar, Priti; Parimisetty, Avinash; Lefebvre d’Hellencourt, Christian; Ravanan, Palaniyandi

    2014-01-01

    Execution of fundamental cellular functions demands regulated protein folding homeostasis. Endoplasmic reticulum (ER) is an active organelle existing to implement this function by folding and modifying secretory and membrane proteins. Loss of protein folding homeostasis is central to various diseases and budding evidences suggest ER stress as being a major contributor in the development or pathology of a diseased state besides other cellular stresses. The trigger for diseases may be diverse but, inflammation and/or ER stress may be basic mechanisms increasing the severity or complicating the condition of the disease. Chronic ER stress and activation of the unfolded-protein response (UPR) through endogenous or exogenous insults may result in impaired calcium and redox homeostasis, oxidative stress via protein overload thereby also influencing vital mitochondrial functions. Calcium released from the ER augments the production of mitochondrial Reactive Oxygen Species (ROS). Toxic accumulation of ROS within ER and mitochondria disturbs fundamental organelle functions. Sustained ER stress is known to potentially elicit inflammatory responses via UPR pathways. Additionally, ROS generated through inflammation or mitochondrial dysfunction could accelerate ER malfunction. Dysfunctional UPR pathways have been associated with a wide range of diseases including several neurodegenerative diseases, stroke, metabolic disorders, cancer, inflammatory disease, diabetes mellitus, cardiovascular disease, and others. In this review, we have discussed the UPR signaling pathways, and networking between ER stress-induced inflammatory pathways, oxidative stress, and mitochondrial signaling events, which further induce or exacerbate ER stress. PMID:25120434

  6. Obesity and endoplasmic reticulum (ER) stresses

    PubMed Central

    Tripathi, Yamini B.; Pandey, Vivek

    2012-01-01

    In obesity, the adipose cells behave as inflammatory source and result to low grade inflammation. This systemic inflammation along with oxidative stress is a silent killer and damages other vital organs also. High metabolic process, induced due to high nutritional intake, results to endoplasmic reticulum (ER) stress and mitochondrial stress. This review describes the triggering factor and basic mechanism behind the obesity mediated these stresses in relation to inflammation. Efforts have been made to describe the effect-response cycle between adipocytes and non-adipocyte cells with reference to metabolic syndrome (MS). PMID:22891067

  7. Endoplasmic Reticulum Stress Response in Arabidopsis Roots

    PubMed Central

    Cho, Yueh; Kanehara, Kazue

    2017-01-01

    Roots are the frontier of plant body to perceive underground environmental change. Endoplasmic reticulum (ER) stress response represents circumvention of cellular stress caused by various environmental changes; however, a limited number of studies are available on the ER stress responses in roots. Here, we report the tunicamycin (TM) -induced ER stress response in Arabidopsis roots by monitoring expression patterns of immunoglobulin-binding protein 3 (BiP3), a representative marker for the response. Roots promptly responded to the TM-induced ER stress through the induction of similar sets of ER stress-responsive genes. However, not all cells responded uniformly to the TM-induced ER stress in roots, as BiP3 was highly expressed in root tips, an outer layer in elongation zone, and an inner layer in mature zone of roots. We suggest that ER stress response in roots has tissue specificity. PMID:28298914

  8. 2-DEOXY-GLUCOSE DOWN REGULATES ENDOTHELIAL AKT AND ERK VIA INTERFERENCE WITH N-LINKED GLYCOSYLATION, INDUCTION OF ENDOPLASMIC RETICULUM STRESS AND GSK-3β ACTIVATION

    PubMed Central

    Kovács, Krisztina; Decatur, Christina; Toro, Marcela; Pham, Dien G.; Liu, Huaping; Jing, Yuqi; Murray, Timothy G.; Lampidis, Theodore J.; Merchan, Jaime R.

    2015-01-01

    Interference with endothelial cell metabolism is a promising, yet unexploited strategy for angiogenesis inhibition. We reported that the glucose analog, 2-deoxy-D-Glucose (2-DG) inhibits angiogenesis at significantly lower concentrations than those required for tumor cytotoxicity. Here, we found that hypersensitivity to 2-DG in endothelial cells is not associated with enhanced drug uptake compared to tumor cells, but with time dependent, endothelial selective inhibition of Akt and Erk phosphorylation. Down regulation of these critical survival pathways is shown to be due to 2-DG’s interference with N-linked glycosylation, leading to alterations in VEGFR2 (and downstream signaling) as well as induction of endoplasmic reticulum (ER) stress, GSK-3β activation and apoptosis. In vivo, periocular administration of 2-DG in LHBETATAG mice was associated with significant reduction of newly formed (CD 105 +) tumor capillaries, ER stress (GRP 78 expression), and endothelial apoptosis (TUNEL). These findings uniquely link N-linked glycosylation inhibition, ER stress and Erk/Akt down regulation in endothelial cells, and provide a novel drug development strategy to overcome resistance mechanisms to currently available antiangiogenic agents. PMID:26637370

  9. Endoplasmic Reticulum Stress and Associated ROS

    PubMed Central

    Zeeshan, Hafiz Maher Ali; Lee, Geum Hwa; Kim, Hyung-Ryong; Chae, Han-Jung

    2016-01-01

    The endoplasmic reticulum (ER) is a fascinating network of tubules through which secretory and transmembrane proteins enter unfolded and exit as either folded or misfolded proteins, after which they are directed either toward other organelles or to degradation, respectively. The ER redox environment dictates the fate of entering proteins, and the level of redox signaling mediators modulates the level of reactive oxygen species (ROS). Accumulating evidence suggests the interrelation of ER stress and ROS with redox signaling mediators such as protein disulfide isomerase (PDI)-endoplasmic reticulum oxidoreductin (ERO)-1, glutathione (GSH)/glutathione disuphide (GSSG), NADPH oxidase 4 (Nox4), NADPH-P450 reductase (NPR), and calcium. Here, we reviewed persistent ER stress and protein misfolding-initiated ROS cascades and their significant roles in the pathogenesis of multiple human disorders, including neurodegenerative diseases, diabetes mellitus, atherosclerosis, inflammation, ischemia, and kidney and liver diseases. PMID:26950115

  10. Endoplasmic Reticulum (ER) Stress and Endocrine Disorders

    PubMed Central

    Ariyasu, Daisuke; Yoshida, Hiderou; Hasegawa, Yukihiro

    2017-01-01

    The endoplasmic reticulum (ER) is the organelle where secretory and membrane proteins are synthesized and folded. Unfolded proteins that are retained within the ER can cause ER stress. Eukaryotic cells have a defense system called the “unfolded protein response” (UPR), which protects cells from ER stress. Cells undergo apoptosis when ER stress exceeds the capacity of the UPR, which has been revealed to cause human diseases. Although neurodegenerative diseases are well-known ER stress-related diseases, it has been discovered that endocrine diseases are also related to ER stress. In this review, we focus on ER stress-related human endocrine disorders. In addition to diabetes mellitus, which is well characterized, several relatively rare genetic disorders such as familial neurohypophyseal diabetes insipidus (FNDI), Wolfram syndrome, and isolated growth hormone deficiency type II (IGHD2) are discussed in this article. PMID:28208663

  11. A LAPF/phafin1-like protein regulates TORC1 and lysosomal membrane permeabilization in response to endoplasmic reticulum membrane stress

    PubMed Central

    Kim, Adam; Cunningham, Kyle W.

    2015-01-01

    Lysosomal membrane permeabilization (LMP) is a poorly understood regulator of programmed cell death that involves leakage of luminal lysosomal or vacuolar hydrolases into the cytoplasm. In Saccharomyces cerevisiae, LMP can be induced by antifungals and endoplasmic reticulum stressors when calcineurin also has been inactivated. A genome-wide screen revealed Pib2, a relative of LAPF/phafin1 that regulates LMP in mammals, as a pro-LMP protein in yeast. Pib2 associated with vacuolar and endosomal limiting membranes in unstressed cells in a manner that depended on its FYVE domain and on phosphatidylinositol 3-phosphate (PI(3)P) biosynthesis. Genetic experiments suggest that Pib2 stimulates the activity of TORC1, a vacuole-associated protein kinase that is sensitive to rapamycin, in a pathway parallel to the Ragulator/EGO complex containing the GTPases Gtr1 and Gtr2. A hyperactivating mutation in the catalytic subunit of TORC1 restored LMP to the gtr1∆ and pib2∆ mutants and also prevented the synthetic lethality of the double mutants. These findings show novel roles of PI(3)P and Pib2 in the regulation of TORC1, which in turn promoted LMP and nonapoptotic death of stressed cells. Rapamycin prevented the death of the pathogenic yeast Candida albicans during exposure to fluconazole plus a calcineurin inhibitor, suggesting that TORC1 broadly promotes sensitivity to fungistats in yeasts. PMID:26510498

  12. Cardioprotective effects of Notoginsenoside R1 against ischemia/reperfusion injuries by regulating oxidative stress- and endoplasmic reticulum stress- related signaling pathways

    PubMed Central

    Yu, Yingli; Sun, Guibo; Luo, Yun; Wang, Min; Chen, Rongchang; Zhang, Jingyi; Ai, Qidi; Xing, Na; Sun, Xiaobo

    2016-01-01

    Background: Recent reports suggested the involvement of oxidative stress- and endoplasmic reticulum stress (ERS)-associated pathways in the progression of ischemia/reperfusion (I/R) injury. Notoginsenoside R1 (NGR1) is a novel saponin isolated from P. notoginseng, which has a history of prevention and treatment of cardiovascular diseases. Objective: We aimed to examine the cardioprotective effects of NGR1 on I/R-induced heart dysfunction ex vivo and in vitro. Methods: H9c2 cadiomyocytes were incubated with NGR1 for 24 h and exposed to hypoxia/reoxygenation. Isolated rat hearts were perfused by NGR1 for 15 min and then subjected to global ischemia/reperfusion. Hemodynamic parameters were monitored as left ventricular systolic pressure (LVSP), heart rate, and maximal rate of increase and decrease of left ventricular pressure (±dP/dt max/min). Results: NGR1 pretreatment prevents cell apoptosis and delays the onset of ERS by decreasing the protein expression levels of ERS-responsive proteins GRP78, P-PERK, ATF6, IRE, and inhibiting the expression of pro-apoptosis proteins CHOP, Caspase-12, and P-JNK. Besides, NGR1 scavenges free radical, and increases the activity of antioxidase. NGR1 inhibits Tunicamycin-induced cell death and cardic dysfunction. Conclusion: We elucidated the significant cardioprotective effects of NGR1 against I/R injuries, and demonstrated the involvement of oxidative stress and ERS in the protective effects of NGR1. PMID:26888485

  13. Placental endoplasmic reticulum stress negatively regulates transcription of placental growth factor via ATF4 and ATF6β: implications for the pathophysiology of human pregnancy complications.

    PubMed

    Mizuuchi, Masahito; Cindrova-Davies, Tereza; Olovsson, Matts; Charnock-Jones, D Stephen; Burton, Graham J; Yung, Hong Wa

    2016-03-01

    Low maternal circulating concentrations of placental growth factor (PlGF) are one of the hallmarks of human pregnancy complications, including fetal growth restriction (FGR) and early-onset pre-eclampsia (PE). Currently, PlGF is used clinically with other biomarkers to screen for high-risk cases, although the mechanisms underlying its regulation are largely unknown. Placental endoplasmic reticulum (ER) stress has recently been found to be elevated in cases of FGR, and to an even greater extent in early-onset PE complicated with FGR. ER stress activates the unfolded protein response (UPR); attenuation of protein translation and a reduction in cell growth and proliferation play crucial roles in the pathophysiology of these complications of pregnancy. In this study, we further identified that ER stress regulates release of PlGF. We first observed that down-regulation of PlGF protein was associated with nuclear localization of ATF4, ATF6α and ATF6β in the syncytiotrophoblast of placentae from PE patients. Transcript analysis showed a decrease of PlGF mRNA, and an increase from genes encoding those UPR transcription factors in placentae from cases of early-onset PE, but not of late-onset (>34 weeks) PE, compared to term controls. Further investigations indicated a strong correlation between ATF4 and PlGF mRNA levels only (r = - 0.73, p < 0.05). These results could be recapitulated in trophoblast-like cells exposed to chemical inducers of ER stress or hypoxia-reoxygenation. The stability of PlGF transcripts was unchanged. The use of small interfering RNA specific for transcription factors in the UPR pathways revealed that ATF4 and ATF6β, but not ATF6α, modulate PlGF transcription. To conclude, ATF4 and ATF6β act synergistically in the negative regulation of PlGF mRNA expression, resulting in reduced PlGF secretion by the trophoblast in response to stress. Therefore, these results further support the targeting of placental ER stress as a potential new therapeutic

  14. The asthma-associated ORMDL3 gene product regulates endoplasmic reticulum-mediated calcium signaling and cellular stress.

    PubMed

    Cantero-Recasens, Gerard; Fandos, César; Rubio-Moscardo, Fanny; Valverde, Miguel A; Vicente, Rubén

    2010-01-01

    Alterations of protein folding or Ca(2+) levels within the endoplasmic reticulum (ER) result in the unfolded-protein response (UPR), a process considered as an endogenous inducer of inflammation. Thereby, understanding how genetic factors modify UPR is particularly relevant in chronic inflammatory diseases such as asthma. Here we identified that ORMDL3, the only genetic risk factor recently associated to asthma in a genome wide study, alters ER-mediated Ca(2+) homeostasis and facilitates the UPR. Heterologous expression of human ER-resident transmembrane ORMDL3 protein increased resting cytosolic Ca(2+) levels and reduced ER-mediated Ca(2+) signaling, an effect reverted by co-expression with the sarco-endoplasmic reticulum Ca(2+) pump (SERCA). Increased ORMDL3 expression also promoted stronger activation of UPR transducing molecules and target genes while siRNA-mediated knock-down of endogenous ORMDL3 potentiated ER Ca(2+) release and attenuated the UPR. In conclusion, our findings are consistent with a model in which ORMDL3 binds and inhibits SERCA resulting in a reduced ER Ca(2+) concentration and increased UPR. Thus, we provide a first insight into the molecular mechanism explaining the association of ORMDL3 with proinflammatory diseases.

  15. An endoplasmic reticulum stress-regulated lncRNA hosting a microRNA megacluster induces early features of diabetic nephropathy.

    PubMed

    Kato, Mitsuo; Wang, Mei; Chen, Zhuo; Bhatt, Kirti; Oh, Hyung Jung; Lanting, Linda; Deshpande, Supriya; Jia, Ye; Lai, Jennifer Y C; O'Connor, Christopher L; Wu, YiFan; Hodgin, Jeffrey B; Nelson, Robert G; Bitzer, Markus; Natarajan, Rama

    2016-09-30

    It is important to find better treatments for diabetic nephropathy (DN), a debilitating renal complication. Targeting early features of DN, including renal extracellular matrix accumulation (ECM) and glomerular hypertrophy, can prevent disease progression. Here we show that a megacluster of nearly 40 microRNAs and their host long non-coding RNA transcript (lnc-MGC) are coordinately increased in the glomeruli of mouse models of DN, and mesangial cells treated with transforming growth factor-β1 (TGF- β1) or high glucose. Lnc-MGC is regulated by an endoplasmic reticulum (ER) stress-related transcription factor, CHOP. Cluster microRNAs and lnc-MGC are decreased in diabetic Chop(-/-) mice that showed protection from DN. Target genes of megacluster microRNAs have functions related to protein synthesis and ER stress. A chemically modified oligonucleotide targeting lnc-MGC inhibits cluster microRNAs, glomerular ECM and hypertrophy in diabetic mice. Relevance to human DN is also demonstrated. These results demonstrate the translational implications of targeting lnc-MGC for controlling DN progression.

  16. Endoplasmic reticulum stress: implications for inflammatory bowel disease pathogenesis

    PubMed Central

    Kaser, Arthur; Martínez-Naves, Eduardo; Blumberg, Richard S.

    2015-01-01

    Purpose of review To provide an overview of the emerging role of cellular stress responses in inflammatory bowel disease (IBD). Recent findings The unfolded protein response (UPR) is a primitive cellular pathway that is engaged when responding to endoplasmic reticulum stress and regulates autophagy. Highly secretory cells such as Paneth cells and goblet cells in the intestines are particularly susceptible to endoplasmic reticulum stress and are exceedingly dependent upon a properly functioning UPR to maintain cellular viability and homeostasis. Primary genetic abnormalities within the components of the UPR (e.g. XBP1, ARG2, ORMDL3), genes that encode proteins reliant upon a robust secretory pathway (e.g. MUC2, HLAB27) and environmental factors that create disturbances in the UPR (e.g. microbial products and inflammatory cytokines) are important factors in the primary development and/or perpetuation of intestinal inflammation. Summary Endoplasmic reticulum stress is an important new pathway involved in the development of intestinal inflammation associated with IBD and likely other intestinal inflammatory disorders. PMID:20495455

  17. Endoplasmic reticulum stress eIF2α–ATF4 pathway-mediated cyclooxygenase-2 induction regulates cadmium-induced autophagy in kidney

    PubMed Central

    Luo, B; Lin, Y; Jiang, S; Huang, L; Yao, H; Zhuang, Q; Zhao, R; Liu, H; He, C; Lin, Z

    2016-01-01

    The heavy metal cadmium (Cd) is nephrotoxic. Recent studies show that autophagy plays an essential role in Cd-induced kidney injury. However, the mechanisms of Cd-induced kidney injury accompanied by autophagy are still obscure. In the present study, we first confirmed that Cd induced kidney damage and dysfunction, along with autophagy, both in vivo and in vitro. Then, we observed that cyclooxygenase-2 (COX-2) and the eIF2α–ATF4 pathway of endoplasmic reticulum (ER) stress were induced by Cd in both kidney tissues and cultured cells. Further studies showed that inhibition of COX-2 with celecoxib or RNA interference (RNAi) inhibited the Cd-induced autophagy in kidney cells. In addition, blocking ER stress with 4-phenylbutyrate or RNAi partially counteracted COX-2 overexpression and autophagy induced by Cd, which suggested that ER stress was required for Cd-induced kidney autophagy. Significantly, our results showed that Cd activated ATF4 and induced its translocation to the nucleus. Knockdown of ATF4 inhibited Cd-induced COX-2 overexpression. While COX-2 overexpression is involved in renal dysfunction, there is no prior report on the role of COX-2 in autophagy regulation. The results of the current study suggest a novel molecular mechanism that the ER stress eIF2α–ATF4 pathway-mediated COX-2 overexpression contributes to Cd-induced kidney autophagy and injury. The present study implies that COX-2 may be a potential target for therapy against Cd-induced nephrotoxicity. PMID:27253415

  18. FPipTB, a benzimidazole derivative, induces chondrosarcoma cell apoptosis via endoplasmic reticulum stress and apoptosis signal-regulating kinase 1.

    PubMed

    Liu, Ju-Fang; Chang, Chih-Shiang; Fong, Yi-Chin; Kuo, Sheng-Chu; Tang, Chih-Hsin

    2012-04-01

    Chondrosarcoma is the second most common primary bone tumor and it responds poorly to both chemotherapy and radiation treatment. In this study, we investigated the anticancer effects of a new benzimidazole derivative, 2-(furanyl)-5-(piperidinyl)- (3,4,5-trimethoxybenzyl) benzimidazole (FPipTB) in human chondrosarcoma cells. FPipTB-induced apoptosis in human chondrosarcoma cell lines (JJ012 and SW1353) but not in primary chondrocytes. Furthermore, it triggered endoplasmic reticulum (ER) stress, which was characterized by changes in cytosolic calcium levels. Treatment of chondrosarcoma cells with FPipTB was associated with increased intracellular levels of ASK1, p38, p53, and Bax, followed by release of cytochrome c from mitochondria and activation of caspases. It is also known that ER stress activates apoptosis signal-regulating kinase 1 (ASK1), which mediates activation of JNK and p38 pathways. We also found that FPipTB-induced p38 and p53 phosphorylation and upregulated Bax expression. To study the mechanism of Bax upregulation, we determined that Bax promoter activity was increased in FPipTB-treated cells, leading to an increase in intracellular levels of Bax. In addition, cell treated with Ca(2+) chelator or p38 inhibitor showed reduced transcriptional activity. The results further suggest that FPipTB triggered ER stress, as indicated by changes in cytosolic calcium levels and activated the ASK1-MKK3/6-p38-p53-Bax pathway, causing chondrosarcoma cell death. Importantly, animal studies revealed a dramatic 40% reduction in tumor volume after 21 d of treatment. Thus, FPipTB may be a novel anticancer agent for the treatment of chondrosarcoma.

  19. Cantharidin Induced Oral Squamous Cell Carcinoma Cell Apoptosis via the JNK-Regulated Mitochondria and Endoplasmic Reticulum Stress-Related Signaling Pathways

    PubMed Central

    Su, Chin-Chuan; Lee, Kuan-I; Chen, Mu-Kuan; Kuo, Chun-Ying; Tang, Chih-Hsin; Liu, Shing Hwa

    2016-01-01

    Oral cancer is a subtype of head and neck cancer which represents 2.65% of all human malignancies. Most of oral cancer is histopathologically diagnosed as oral squamous cell carcinoma (OSCC). OSCC is characterized by a high degree of local invasion and a high rate of metastasis to the cervical lymph nodes. How to prevention and treatment of OSCC is important and imperative. Here, we investigated the therapeutic effect and molecular mechanism of cantharidin, an active compound isolated from blister beetles, on OSCC in vitro. Results showed that cantharidin significantly decreased cell viability in human tongue squamous carcinoma-derived SAS, CAL-27, and SCC-4 cell lines. The further mechanistic studies were carried out in SAS cells. Cantharidin also significantly increased apoptosis-related signals, including caspase-9, caspase-7 and caspase-3 proteins. Besides, cantharidin decreased mitochondrial transmembrane potential (MMP) and induced cytochrome c and apoptosis inducing factor (AIF) release. Cantharidin also increased Bax, Bid, and Bak protein expressions and decreased Bcl-2 protein expression. Cantharidin could also increase the endoplasmic reticulum (ER) stress signals, including the expressions of phosphorylated eIF-2α and CHOP, but not Grp78 and Grp94. Furthermore, cantharidin reduced pro-caspase-12 protein expression. In signals of mitogen-activated protein kinases, cantharidin increased the phosphorylation of JNK, but not ERK and p38. Transfection of shRNA-JNK to OSCC cells effectively reversed the cantharidin-induced cell apoptotic signals, including the mitochondrial and ER stress-related signaling molecules. Taken together, these findings suggest that cantharidin induces apoptosis in OSCC cells via the JNK-regulated mitochondria and ER stress-related signaling pathways. PMID:27930712

  20. Endoplasmic reticulum stress causes EBV lytic replication

    PubMed Central

    Taylor, Gwen Marie; Raghuwanshi, Sandeep K.; Rowe, David T.; Wadowsky, Robert M.

    2011-01-01

    Endoplasmic reticulum (ER) stress triggers a homeostatic cellular response in mammalian cells to ensure efficient folding, sorting, and processing of client proteins. In lytic-permissive lymphoblastoid cell lines (LCLs), pulse exposure to the chemical ER-stress inducer thapsigargin (TG) followed by recovery resulted in the activation of the EBV immediate-early (BRLF1, BZLF1), early (BMRF1), and late (gp350) genes, gp350 surface expression, and virus release. The protein phosphatase 1 a (PP1a)–specific phosphatase inhibitor Salubrinal (SAL) synergized with TG to induce EBV lytic genes; however, TG treatment alone was sufficient to activate EBV lytic replication. SAL showed ER-stress–dependent and –independent antiviral effects, preventing virus release in human LCLs and abrogating gp350 expression in 12-O-tetradecanoylphorbol-13-acetate (TPA)–treated B95-8 cells. TG resulted in sustained BCL6 but not BLIMP1 or CD138 expression, which is consistent with maintenance of a germinal center B-cell, rather than plasma-cell, phenotype. Microarray analysis identified candidate genes governing lytic replication in LCLs undergoing ER stress. PMID:21849482

  1. Stress Responses from the Endoplasmic Reticulum in Cancer

    PubMed Central

    Kato, Hironori; Nishitoh, Hideki

    2015-01-01

    The endoplasmic reticulum (ER) is a dynamic organelle that is essential for multiple cellular functions. During cellular stress conditions, including nutrient deprivation and dysregulation of protein synthesis, unfolded/misfolded proteins accumulate in the ER lumen, resulting in activation of the unfolded protein response (UPR). The UPR also contributes to the regulation of various intracellular signaling pathways such as calcium signaling and lipid signaling. More recently, the mitochondria-associated ER membrane (MAM), which is a site of close contact between the ER and mitochondria, has been shown to function as a platform for various intracellular stress responses including apoptotic signaling, inflammatory signaling, the autophagic response, and the UPR. Interestingly, in cancer, these signaling pathways from the ER are often dysregulated, contributing to cancer cell metabolism. Thus, the signaling pathway from the ER may be a novel therapeutic target for various cancers. In this review, we discuss recent research on the roles of stress responses from the ER, including the MAM. PMID:25941664

  2. Endoplasmic Reticulum Stress Plays a Key Role in the Pathogenesis of Diabetic Peripheral Neuropathy

    PubMed Central

    Lupachyk, Sergey; Watcho, Pierre; Stavniichuk, Roman; Shevalye, Hanna; Obrosova, Irina G.

    2013-01-01

    Endoplasmic reticulum stress resulting from abnormal folding of newly synthesized proteins impairs metabolism, transcriptional regulation, and gene expression, and it is a key mechanism of cell injury. Endoplasmic reticulum stress plays an important role in cardiovascular and neurodegenerative diseases, cancer, and diabetes. We evaluated the role for this phenomenon in diabetic peripheral neuropathy. Endoplasmic reticulum stress manifest in upregulation of multiple components of unfolded protein response was identified in neural tissues (sciatic nerve, spinal cord) of streptozotocin diabetic rats and mice. A chemical chaperone, trimethylamine oxide, administered for 12 weeks after induction of diabetes (110 mg⋅kg−1⋅d−1, a prevention paradigm) attenuated endoplasmic reticulum stress, peripheral nerve dysfunction, intraepidermal nerve fiber loss, and sciatic nerve and spinal cord oxidative-nitrative stress in streptozotocin diabetic rats. Similar effects on diabetes-induced endoplasmic reticulum stress and peripheral nerve dysfunction were observed with a structurally unrelated chemical chaperone, 4-phenylbutyric acid (100 mg⋅kg−1⋅d−1, intraperitoneal). CCAAT/enhancer-binding protein homologous protein (CHOP)−/− mice made diabetic with streptozotocin displayed less severe sciatic nerve oxidative-nitrative stress and peripheral neuropathy than the wild-type (C57Bl6/J) mice. Neither chemical chaperones nor CHOP gene deficiency reduced diabetic hyperglycemia. Our findings reveal an important role of endoplasmic reticulum stress in the development of diabetic peripheral neuropathy and identify a potential new therapeutic target. PMID:23364451

  3. Development of Endoplasmic Reticulum Stress during Experimental Oxalate Nephrolithiasis.

    PubMed

    Motin, Yu G; Lepilov, A V; Bgatova, N P; Zharikov, A Yu; Motina, N V; Lapii, G A; Lushnikova, E L; Nepomnyashchikh, L M

    2016-01-01

    Morphological and ultrastructural study of the kidney was performed in rats with oxalate nephrolithiasis. Specific features of endoplasmic reticulum stress were evaluated during nephrolithiasis and treatment with α-tocopherol. We observed the signs of endoplasmic reticulum stress with activation of proapoptotic pathways and injury to the cell lining in nephron tubules and collecting ducts. Ultrastructural changes were found in the organelles, nuclei, and cell membranes of epitheliocytes. A relationship was revealed between endoplasmic reticulum stress and oxidative damage, which developed at the early state of lithogenesis.

  4. Oxidative stress contributes to autophagy induction in response to endoplasmic reticulum stress in Chlamydomonas reinhardtii.

    PubMed

    Pérez-Martín, Marta; Pérez-Pérez, María Esther; Lemaire, Stéphane D; Crespo, José L

    2014-10-01

    The accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER) results in the activation of stress responses, such as the unfolded protein response or the catabolic process of autophagy to ultimately recover cellular homeostasis. ER stress also promotes the production of reactive oxygen species, which play an important role in autophagy regulation. However, it remains unknown whether reactive oxygen species are involved in ER stress-induced autophagy. In this study, we provide evidence connecting redox imbalance caused by ER stress and autophagy activation in the model unicellular green alga Chlamydomonas reinhardtii. Treatment of C. reinhardtii cells with the ER stressors tunicamycin or dithiothreitol resulted in up-regulation of the expression of genes encoding ER resident endoplasmic reticulum oxidoreductin1 oxidoreductase and protein disulfide isomerases. ER stress also triggered autophagy in C. reinhardtii based on the protein abundance, lipidation, cellular distribution, and mRNA levels of the autophagy marker ATG8. Moreover, increases in the oxidation of the glutathione pool and the expression of oxidative stress-related genes were detected in tunicamycin-treated cells. Our results revealed that the antioxidant glutathione partially suppressed ER stress-induced autophagy and decreased the toxicity of tunicamycin, suggesting that oxidative stress participates in the control of autophagy in response to ER stress in C. reinhardtii In close agreement, we also found that autophagy activation by tunicamycin was more pronounced in the C. reinhardtii sor1 mutant, which shows increased expression of oxidative stress-related genes.

  5. Fucoidan induces Toll-like receptor 4-regulated reactive oxygen species and promotes endoplasmic reticulum stress-mediated apoptosis in lung cancer

    PubMed Central

    Hsu, Hsien-Yeh; Lin, Tung-Yi; Lu, Mei-Kuang; Leng, Pei-Ju; Tsao, Shu-Ming; Wu, Yu-Chung

    2017-01-01

    Fucoidan, a sulfated polysaccharide extracted from brown algae, exhibits anti-cancer activity. However, the effects and mechanism of fucoidan-induced apoptosis via endoplasmic reticulum (ER) stress is unclear. In this study, we demonstrated that fucoidan prevents tumorigenesis and reduces tumor size in LLC1-xenograft male C57BL/6 mice. Fucoidan induces an ER stress response by activating the PERK-ATF4-CHOP pathway, resulting in apoptotic cell death in vitro and in vivo. Furthermore, ATF4 knockdown abolishes fucoidan-induced CHOP expression and rescues cell viability. Specifically, fucoidan increases intracellular reactive oxygen species (ROS), which increase ATF4 and CHOP in lung cancer cells. Using the ROS scavenger N-acetyl-l-cysteine (NAC), we found that ROS generation is involved in fucoidan-induced ER stress-mediated apoptosis. Moreover, via Toll-like receptor 4 (TLR4) knockdown, we demonstrated that fucoidan-induced ROS and CHOP expression were attenuated. Our study is the first to identify a novel mechanism for the antitumor activity of fucoidan. We showed that fucoidan inhibits tumor viability by activating the TLR4/ROS/ER stress axis and the downstream PERK-ATF4-CHOP pathway, leading to apoptosis and suppression of lung cancer cell progression. Together, these results indicate that fucoidan is a potential preventive and therapeutic agent for lung cancer that acts via activation of ROS-dependent ER stress pathways. PMID:28332554

  6. Fucoidan induces Toll-like receptor 4-regulated reactive oxygen species and promotes endoplasmic reticulum stress-mediated apoptosis in lung cancer.

    PubMed

    Hsu, Hsien-Yeh; Lin, Tung-Yi; Lu, Mei-Kuang; Leng, Pei-Ju; Tsao, Shu-Ming; Wu, Yu-Chung

    2017-03-23

    Fucoidan, a sulfated polysaccharide extracted from brown algae, exhibits anti-cancer activity. However, the effects and mechanism of fucoidan-induced apoptosis via endoplasmic reticulum (ER) stress is unclear. In this study, we demonstrated that fucoidan prevents tumorigenesis and reduces tumor size in LLC1-xenograft male C57BL/6 mice. Fucoidan induces an ER stress response by activating the PERK-ATF4-CHOP pathway, resulting in apoptotic cell death in vitro and in vivo. Furthermore, ATF4 knockdown abolishes fucoidan-induced CHOP expression and rescues cell viability. Specifically, fucoidan increases intracellular reactive oxygen species (ROS), which increase ATF4 and CHOP in lung cancer cells. Using the ROS scavenger N-acetyl-l-cysteine (NAC), we found that ROS generation is involved in fucoidan-induced ER stress-mediated apoptosis. Moreover, via Toll-like receptor 4 (TLR4) knockdown, we demonstrated that fucoidan-induced ROS and CHOP expression were attenuated. Our study is the first to identify a novel mechanism for the antitumor activity of fucoidan. We showed that fucoidan inhibits tumor viability by activating the TLR4/ROS/ER stress axis and the downstream PERK-ATF4-CHOP pathway, leading to apoptosis and suppression of lung cancer cell progression. Together, these results indicate that fucoidan is a potential preventive and therapeutic agent for lung cancer that acts via activation of ROS-dependent ER stress pathways.

  7. Up-Regulation of mRNA Ventricular PRNP Prion Protein Gene Expression in Air Pollution Highly Exposed Young Urbanites: Endoplasmic Reticulum Stress, Glucose Regulated Protein 78, and Nanosized Particles

    PubMed Central

    Villarreal-Calderon, Rodolfo; Franco-Lira, Maricela; González-Maciel, Angélica; Reynoso-Robles, Rafael; Harritt, Lou; Pérez-Guillé, Beatriz; Ferreira-Azevedo, Lara; Drecktrah, Dan; Zhu, Hongtu; Sun, Qiang; Torres-Jardón, Ricardo; Aragón-Flores, Mariana; Calderón-Garcidueñas, Ana; Diaz, Philippe; Calderón-Garcidueñas, Lilian

    2013-01-01

    Mexico City Metropolitan Area children and young adults exposed to high concentrations of air pollutants including fine and ultrafine particulate matter (PM) vs. clean air controls, exhibit myocardial inflammation and inflammasome activation with a differential right and left ventricular expression of key inflammatory genes and inflammasomes. We investigated the mRNA expression levels of the prion protein gene PRNP, which plays an important role in the protection against oxidative stress and metal toxicity, and the glucose regulated protein 78, a key protein in endoplasmic reticulum (ER) stress signaling, in ventricular autopsy samples from 30 children and young adults age 19.97 ± 6.8 years with a lifetime of low (n:4) vs. high (n:26) air pollution exposures. Light microscopy and transmission electron microscopy studies were carried out in human ventricles, and electron microscopy studies were also done in 5 young, highly exposed Mexico City dogs. There was significant left ventricular PRNP and bi-ventricular GRP78 mRNA up-regulation in Mexico City young urbanites vs. controls. PRNP up-regulation in the left ventricle was significantly different from the right, p < 0.0001, and there was a strong left ventricular PRNP and GRP78 correlation (p = 0.0005). Marked abnormalities in capillary endothelial cells, numerous nanosized particles in myocardial ER and in abnormal mitochondria characterized the highly exposed ventricles. Early and sustained cardiac ER stress could result in detrimental irreversible consequences in urban children, and while highly complex systems maintain myocardial homeostasis, failure to compensate for chronic myocardial inflammation, oxidative and ER stress, and particles damaging myocardial organelles may prime the development of pathophysiological cardiovascular states in young urbanites. Nanosized PM could play a key cardiac myocyte toxicity role. PMID:24287918

  8. Up-regulation of mRNA ventricular PRNP prion protein gene expression in air pollution highly exposed young urbanites: endoplasmic reticulum stress, glucose regulated protein 78, and nanosized particles.

    PubMed

    Villarreal-Calderon, Rodolfo; Franco-Lira, Maricela; González-Maciel, Angélica; Reynoso-Robles, Rafael; Harritt, Lou; Pérez-Guillé, Beatriz; Ferreira-Azevedo, Lara; Drecktrah, Dan; Zhu, Hongtu; Sun, Qiang; Torres-Jardón, Ricardo; Aragón-Flores, Mariana; Calderón-Garcidueñas, Ana; Diaz, Philippe; Calderón-Garcidueñas, Lilian

    2013-11-28

    Mexico City Metropolitan Area children and young adults exposed to high concentrations of air pollutants including fine and ultrafine particulate matter (PM) vs. clean air controls, exhibit myocardial inflammation and inflammasome activation with a differential right and left ventricular expression of key inflammatory genes and inflammasomes. We investigated the mRNA expression levels of the prion protein gene PRNP, which plays an important role in the protection against oxidative stress and metal toxicity, and the glucose regulated protein 78, a key protein in endoplasmic reticulum (ER) stress signaling, in ventricular autopsy samples from 30 children and young adults age 19.97 ± 6.8 years with a lifetime of low (n:4) vs. high (n:26) air pollution exposures. Light microscopy and transmission electron microscopy studies were carried out in human ventricles, and electron microscopy studies were also done in 5 young, highly exposed Mexico City dogs. There was significant left ventricular PRNP and bi-ventricular GRP78 mRNA up-regulation in Mexico City young urbanites vs. controls. PRNP up-regulation in the left ventricle was significantly different from the right, p < 0.0001, and there was a strong left ventricular PRNP and GRP78 correlation (p = 0.0005). Marked abnormalities in capillary endothelial cells, numerous nanosized particles in myocardial ER and in abnormal mitochondria characterized the highly exposed ventricles. Early and sustained cardiac ER stress could result in detrimental irreversible consequences in urban children, and while highly complex systems maintain myocardial homeostasis, failure to compensate for chronic myocardial inflammation, oxidative and ER stress, and particles damaging myocardial organelles may prime the development of pathophysiological cardiovascular states in young urbanites. Nanosized PM could play a key cardiac myocyte toxicity role.

  9. Endoplasmic Reticulum Stress Interacts With Inflammation in Human Diseases.

    PubMed

    Cao, Stewart Siyan; Luo, Katherine L; Shi, Lynn

    2016-02-01

    The endoplasmic reticulum (ER) is a critical organelle for normal cell function and homeostasis. Disturbance in the protein folding process in the ER, termed ER stress, leads to the activation of unfolded protein response (UPR) that encompasses a complex network of intracellular signaling pathways. The UPR can either restore ER homeostasis or activate pro-apoptotic pathways depending on the type of insults, intensity and duration of the stress, and cell types. ER stress and the UPR have recently been linked to inflammation in a variety of human pathologies including autoimmune, infectious, neurodegenerative, and metabolic disorders. In the cell, ER stress and inflammatory signaling share extensive regulators and effectors in a broad spectrum of biological processes. In spite of different etiologies, the two signaling pathways have been shown to form a vicious cycle in exacerbating cellular dysfunction and causing apoptosis in many cells and tissues. However, the interaction between ER stress and inflammation in many of these diseases remains poorly understood. Further understanding of the biochemistry, cell biology, and physiology may enable the development of novel therapies that spontaneously target these pathogenic pathways.

  10. Endoplasmic Reticulum Stress Is Chronically Activated in Chronic Pancreatitis*

    PubMed Central

    Sah, Raghuwansh P.; Garg, Sushil K.; Dixit, Ajay K.; Dudeja, Vikas; Dawra, Rajinder K.; Saluja, Ashok K.

    2014-01-01

    The pathogenesis of chronic pancreatitis (CP) is poorly understood. Endoplasmic reticulum (ER) stress has now been recognized as a pathogenic event in many chronic diseases. However, ER stress has not been studied in CP, although pancreatic acinar cells seem to be especially vulnerable to ER dysfunction because of their dependence on high ER volume and functionality. Here, we aim to investigate ER stress in CP, study its pathogenesis in relation to trypsinogen activation (widely regarded as the key event of pancreatitis), and explore its mechanism, time course, and downstream consequences during pancreatic injury. CP was induced in mice by repeated episodes of acute pancreatitis (AP) based on caerulein hyperstimulation. ER stress leads to activation of unfolded protein response components that were measured in CP and AP. We show sustained up-regulation of unfolded protein response components ATF4, CHOP, GRP78, and XBP1 in CP. Overexpression of GRP78 and ATF4 in human CP confirmed the experimental findings. We used novel trypsinogen-7 knock-out mice (T−/−), which lack intra-acinar trypsinogen activation, to clarify the relationship of ER stress to intra-acinar trypsinogen activation in pancreatic injury. Comparable activation of ER stress was seen in wild type and T−/− mice. Induction of ER stress occurred through pathologic calcium signaling very early in the course of pancreatic injury. Our results establish that ER stress is chronically activated in CP and is induced early in pancreatic injury through pathologic calcium signaling independent of trypsinogen activation. ER stress may be an important pathogenic mechanism in pancreatitis that needs to be explored in future studies. PMID:25077966

  11. Endoplasmic reticulum stress is chronically activated in chronic pancreatitis.

    PubMed

    Sah, Raghuwansh P; Garg, Sushil K; Dixit, Ajay K; Dudeja, Vikas; Dawra, Rajinder K; Saluja, Ashok K

    2014-10-03

    The pathogenesis of chronic pancreatitis (CP) is poorly understood. Endoplasmic reticulum (ER) stress has now been recognized as a pathogenic event in many chronic diseases. However, ER stress has not been studied in CP, although pancreatic acinar cells seem to be especially vulnerable to ER dysfunction because of their dependence on high ER volume and functionality. Here, we aim to investigate ER stress in CP, study its pathogenesis in relation to trypsinogen activation (widely regarded as the key event of pancreatitis), and explore its mechanism, time course, and downstream consequences during pancreatic injury. CP was induced in mice by repeated episodes of acute pancreatitis (AP) based on caerulein hyperstimulation. ER stress leads to activation of unfolded protein response components that were measured in CP and AP. We show sustained up-regulation of unfolded protein response components ATF4, CHOP, GRP78, and XBP1 in CP. Overexpression of GRP78 and ATF4 in human CP confirmed the experimental findings. We used novel trypsinogen-7 knock-out mice (T(-/-)), which lack intra-acinar trypsinogen activation, to clarify the relationship of ER stress to intra-acinar trypsinogen activation in pancreatic injury. Comparable activation of ER stress was seen in wild type and T(-/-) mice. Induction of ER stress occurred through pathologic calcium signaling very early in the course of pancreatic injury. Our results establish that ER stress is chronically activated in CP and is induced early in pancreatic injury through pathologic calcium signaling independent of trypsinogen activation. ER stress may be an important pathogenic mechanism in pancreatitis that needs to be explored in future studies.

  12. BhbZIP60 from Resurrection Plant Boea hygrometrica Is an mRNA Splicing-Activated Endoplasmic Reticulum Stress Regulator Involved in Drought Tolerance

    PubMed Central

    Wang, Bo; Du, Hong; Zhang, Zhennan; Xu, Wenzhong; Deng, Xin

    2017-01-01

    Adverse environmental conditions cause endoplasmic reticulum (ER) stress in plants. To mitigate ER stress damage, ER associated transcription factors and inositol-requiring enzyme-1 (IRE1)-mediated bZIP60 mRNA splicing are activated in plants. A drought-induced gene, encoding the ortholog of AtbZIP60, was identified in the resurrection plant Boea hygrometrica, termed BhbZIP60. In response to ER stress and dehydration, BhbZIP60 mRNA can be spliced to create a frame shift in the C terminus by the excision of 23b segment in a manner of its ortholog in other plants, thus translocating to the nucleus instead of the cytoplasm. The splicing-activated BhbZIP60 (BhbZIP60S) could function in the same way as its Arabidopsis ortholog by restoring the molecular phenotype of the mutant atbzip60. When overexpressed in Arabidopsis, BhbZIP60S provided transgenic plants with enhanced tolerance to drought, tunicamycin and mannitol stresses with upregulation of the expressions of ER quality control (QC) genes (BiP2, BiP3, CNX1, and sPDI) and abscisic acid (ABA) responsive genes (RD29A, RAB18, and RD17). Furthermore, in the yeast one-hybrid system, BhbZIP60S was capable of interacting with ER stress responsive elements (ERSE and ERSE-II) that exist in the promoters of known ER-QC genes, but not binding to ABA responsive cis-elements (ABREs). Our results demonstrated that drought-induced BhbZIP60 may have a function in drought tolerance via the splicing-activated BhbZIP60S to mediate ER-QC by direct binding to the promoters of ER-QC genes. This study evidently demonstrates the involvement of ER-QC in the drought tolerance of Arabidopsis and the desiccation tolerance of the resurrection plant B. hygrometrica. PMID:28286511

  13. BhbZIP60 from Resurrection Plant Boea hygrometrica Is an mRNA Splicing-Activated Endoplasmic Reticulum Stress Regulator Involved in Drought Tolerance.

    PubMed

    Wang, Bo; Du, Hong; Zhang, Zhennan; Xu, Wenzhong; Deng, Xin

    2017-01-01

    Adverse environmental conditions cause endoplasmic reticulum (ER) stress in plants. To mitigate ER stress damage, ER associated transcription factors and inositol-requiring enzyme-1 (IRE1)-mediated bZIP60 mRNA splicing are activated in plants. A drought-induced gene, encoding the ortholog of AtbZIP60, was identified in the resurrection plant Boea hygrometrica, termed BhbZIP60. In response to ER stress and dehydration, BhbZIP60 mRNA can be spliced to create a frame shift in the C terminus by the excision of 23b segment in a manner of its ortholog in other plants, thus translocating to the nucleus instead of the cytoplasm. The splicing-activated BhbZIP60 (BhbZIP60S) could function in the same way as its Arabidopsis ortholog by restoring the molecular phenotype of the mutant atbzip60. When overexpressed in Arabidopsis, BhbZIP60S provided transgenic plants with enhanced tolerance to drought, tunicamycin and mannitol stresses with upregulation of the expressions of ER quality control (QC) genes (BiP2, BiP3, CNX1, and sPDI) and abscisic acid (ABA) responsive genes (RD29A, RAB18, and RD17). Furthermore, in the yeast one-hybrid system, BhbZIP60S was capable of interacting with ER stress responsive elements (ERSE and ERSE-II) that exist in the promoters of known ER-QC genes, but not binding to ABA responsive cis-elements (ABREs). Our results demonstrated that drought-induced BhbZIP60 may have a function in drought tolerance via the splicing-activated BhbZIP60S to mediate ER-QC by direct binding to the promoters of ER-QC genes. This study evidently demonstrates the involvement of ER-QC in the drought tolerance of Arabidopsis and the desiccation tolerance of the resurrection plant B. hygrometrica.

  14. Alginate Oligosaccharide Prevents Acute Doxorubicin Cardiotoxicity by Suppressing Oxidative Stress and Endoplasmic Reticulum-Mediated Apoptosis

    PubMed Central

    Guo, Jun-Jie; Ma, Lei-Lei; Shi, Hong-Tao; Zhu, Jian-Bing; Wu, Jian; Ding, Zhi-Wen; An, Yi; Zou, Yun-Zeng; Ge, Jun-Bo

    2016-01-01

    Doxorubicin (DOX) is a highly potent chemotherapeutic agent, but its usage is limited by dose-dependent cardiotoxicity. DOX-induced cardiotoxicity involves increased oxidative stress and activated endoplasmic reticulum-mediated apoptosis. Alginate oligosaccharide (AOS) is a non-immunogenic, non-toxic and biodegradable polymer, with anti-oxidative, anti-inflammatory and anti-endoplasmic reticulum stress properties. The present study examined whether AOS pretreatment could protect against acute DOX cardiotoxicity, and the underlying mechanisms focused on oxidative stress and endoplasmic reticulum-mediated apoptosis. We found that AOS pretreatment markedly increased the survival rate of mice insulted with DOX, improved DOX-induced cardiac dysfunction and attenuated DOX-induced myocardial apoptosis. AOS pretreatment mitigated DOX-induced cardiac oxidative stress, as shown by the decreased expressions of gp91 (phox) and 4-hydroxynonenal (4-HNE). Moreover, AOS pretreatment significantly decreased the expression of Caspase-12, C/EBP homologous protein (CHOP) (markers for endoplasmic reticulum-mediated apoptosis) and Bax (a downstream molecule of CHOP), while up-regulating the expression of anti-apoptotic protein Bcl-2. Taken together, these findings identify AOS as a potent compound that prevents acute DOX cardiotoxicity, at least in part, by suppression of oxidative stress and endoplasmic reticulum-mediated apoptosis. PMID:27999379

  15. C/EBP β Mediates Endoplasmic Reticulum Stress Regulated Inflammatory Response and Extracellular Matrix Degradation in LPS-Stimulated Human Periodontal Ligament Cells.

    PubMed

    Bai, Yudi; Wei, Yi; Wu, Lian; Wei, Jianhua; Wang, Xiaojing; Bai, Yuxiang

    2016-03-22

    Periodontitis is an oral inflammatory disease that not only affects the integrity of local tooth-supporting tissues but also impacts systemic health. A compositional shift in oral microbiota has been considered as the main cause of periodontitis; however, the potential mechanism has not been fully defined. Herein, we investigated the role of CCAAT/enhancer-binding protein β (C/EBP β), a member of the C/EBP family of transcription factors, in human periodontal ligament cells (hPDLCs) exposed to Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS). RT-PCR and Western blotting analysis showed that the expression of C/EBP β was significantly increased in hPDLCs stimulated with LPS stimuli. Overexpression of C/EBP β by the recombinant adenoviral vector pAd/C/EBP β markedly increased the expression of the pro-inflammatory cytokines IL-6 and IL-8, and matrix metalloproteinases (MMP)-8 and -9 in hPDLCs in response to LPS. Furthermore, the activation of endoplasmic reticulum (ER) stress was confirmed in LPS-stimulated hPDLCs by measuring the expression of the ER stress marker molecules protein kinase-like ER kinase (PERK), eIF2α, GRP78/Bip, and C/EBP homologous protein (CHOP). The ER stress inhibitor salubrinal repressed, but inducer tunicamycin enhanced, the production of IL-6, IL-8, MMP-8, and MMP-9 in hPDLCs. Additionally, ER stress inducer tunicamycin significantly increased the expression level of C/EBP β in hPDLCs. Blocking of C/EBP β by siRNA resulted in a significant decrease in the secretion of IL-6 and IL-8 and expression of MMP-8 and MMP-9 induced by tunicamycin treatment in hPDLCs. Taken together, ER stress appears to play a regulatory role in the inflammatory response and extracellular matrix (ECM) degradation in hPDLCs in response to LPS stimuli by activating C/EBP β expression. This enhances our understanding of human periodontitis pathology.

  16. Silver nanoparticles induce endoplasmatic reticulum stress response in zebrafish

    SciTech Connect

    Christen, Verena; Capelle, Martinus; Fent, Karl

    2013-10-15

    Silver nanoparticles (AgNPs) find increasing applications, and therefore humans and the environment are increasingly exposed to them. However, potential toxicological implications are not sufficiently known. Here we investigate effects of AgNPs (average size 120 nm) on zebrafish in vitro and in vivo, and compare them to human hepatoma cells (Huh7). AgNPs are incorporated in zebrafish liver cells (ZFL) and Huh7, and in zebrafish embryos. In ZFL cells AgNPs lead to induction of reactive oxygen species (ROS), endoplasmatic reticulum (ER) stress response, and TNF-α. Transcriptional alterations also occur in pro-apoptotic genes p53 and Bax. The transcriptional profile differed in ZFL and Huh7 cells. In ZFL cells, the ER stress marker BiP is induced, concomitant with the ER stress marker ATF-6 and spliced XBP-1 after 6 h and 24 h exposure to 0.5 g/L and 0.05 g/L AgNPs, respectively. This indicates the induction of different pathways of the ER stress response. Moreover, AgNPs induce TNF-α. In zebrafish embryos exposed to 0.01, 0.1, 1 and 5 mg/L AgNPs hatching was affected and morphological defects occurred at high concentrations. ER stress related gene transcripts BiP and Synv are significantly up-regulated after 24 h at 0.1 and 5 mg/L AgNPs. Furthermore, transcriptional alterations occurred in the pro-apoptotic genes Noxa and p21. The ER stress response was strong in ZFL cells and occurred in zebrafish embryos as well. Our data demonstrate for the first time that AgNPs lead to induction of ER stress in zebrafish. The induction of ER stress can have several consequences including the activation of apoptotic and inflammatory pathways. - Highlights: • Effects of silver nanoparticles (120 nm AgNPs) are investigated in zebrafish. • AgNPs induce all ER stress reponses in vitro in zebrafish liver cells. • AgNPs induce weak ER stress in zebrafish embryos. • AgNPs induce oxidative stress and transcripts of pro-apoptosis genes.

  17. Apoptosis, autophagy & endoplasmic reticulum stress in diabetes mellitus

    PubMed Central

    Demirtas, Levent; Guclu, Aydin; Erdur, Fatih Mehmet; Akbas, Emin Murat; Ozcicek, Adalet; Onk, Didem; Turkmen, Kultigin

    2016-01-01

    The prevalence of diabetes mellitus (DM) is increasing secondary to increased consumption of food and decreased physical activity worldwide. Hyperglycaemia, insulin resistance and hypertrophy of pancreatic beta cells occur in the early phase of diabetes. However, with the progression of diabetes, dysfunction and loss of beta cells occur in both types 1 and 2 DM. Programmed cell death also named apoptosis is found to be associated with diabetes, and apoptosis of beta cells might be the main mechanism of relative insulin deficiency in DM. Autophagic cell death and apoptosis are not entirely distinct programmed cell death mechanisms and share many of the regulator proteins. These processes can occur in both physiologic and pathologic conditions including DM. Besides these two important pathways, endoplasmic reticulum (ER) also acts as a cell sensor to monitor and maintain cellular homeostasis. ER stress has been found to be associated with autophagy and apoptosis. This review was aimed to describe the interactions between apoptosis, autophagy and ER stress pathways in DM. PMID:28256459

  18. Apoptosis, autophagy & endoplasmic reticulum stress in diabetes mellitus.

    PubMed

    Demirtas, Levent; Guclu, Aydin; Erdur, Fatih Mehmet; Akbas, Emin Murat; Ozcicek, Adalet; Onk, Didem; Turkmen, Kultigin

    2016-10-01

    The prevalence of diabetes mellitus (DM) is increasing secondary to increased consumption of food and decreased physical activity worldwide. Hyperglycaemia, insulin resistance and hypertrophy of pancreatic beta cells occur in the early phase of diabetes. However, with the progression of diabetes, dysfunction and loss of beta cells occur in both types 1 and 2 DM. Programmed cell death also named apoptosis is found to be associated with diabetes, and apoptosis of beta cells might be the main mechanism of relative insulin deficiency in DM. Autophagic cell death and apoptosis are not entirely distinct programmed cell death mechanisms and share many of the regulator proteins. These processes can occur in both physiologic and pathologic conditions including DM. Besides these two important pathways, endoplasmic reticulum (ER) also acts as a cell sensor to monitor and maintain cellular homeostasis. ER stress has been found to be associated with autophagy and apoptosis. This review was aimed to describe the interactions between apoptosis, autophagy and ER stress pathways in DM.

  19. Flavokawain C Inhibits Cell Cycle and Promotes Apoptosis, Associated with Endoplasmic Reticulum Stress and Regulation of MAPKs and Akt Signaling Pathways in HCT 116 Human Colon Carcinoma Cells

    PubMed Central

    Phang, Chung-Weng; Karsani, Saiful Anuar; Sethi, Gautam; Abd Malek, Sri Nurestri

    2016-01-01

    Flavokawain C (FKC) is a naturally occurring chalcone which can be found in Kava (Piper methysticum Forst) root. The present study evaluated the effect of FKC on the growth of various human cancer cell lines and the underlying associated mechanisms. FKC showed higher cytotoxic activity against HCT 116 cells in a time- and dose-dependent manner in comparison to other cell lines (MCF-7, HT-29, A549 and CaSki), with minimal toxicity on normal human colon cells. The apoptosis-inducing capability of FKC on HCT 116 cells was evidenced by cell shrinkage, chromatin condensation, DNA fragmentation and increased phosphatidylserine externalization. FKC was found to disrupt mitochondrial membrane potential, resulting in the release of Smac/DIABLO, AIF and cytochrome c into the cytoplasm. Our results also revealed that FKC induced intrinsic and extrinsic apoptosis via upregulation of the levels of pro-apoptotic proteins (Bak) and death receptors (DR5), while downregulation of the levels of anti-apoptotic proteins (XIAP, cIAP-1, c-FlipL, Bcl-xL and survivin), resulting in the activation of caspase-3, -8 and -9 and cleavage of poly(ADP-ribose) polymerase (PARP). FKC was also found to cause endoplasmic reticulum (ER) stress, as suggested by the elevation of GADD153 protein after FKC treatment. After the cells were exposed to FKC (60μM) over 18hrs, there was a substantial increase in the phosphorylation of ERK 1/2. The expression of phosphorylated Akt was also reduced. FKC also caused cell cycle arrest in the S phase in HCT 116 cells in a time- and dose-dependent manner and with accumulation of cells in the sub-G1 phase. This was accompanied by the downregulation of cyclin-dependent kinases (CDK2 and CDK4), consistent with the upregulation of CDK inhibitors (p21Cip1 and p27Kip1), and hypophosphorylation of Rb. PMID:26859847

  20. CDIP1-BAP31 complex transduces apoptotic signals from endoplasmic reticulum to mitochondria under endoplasmic reticulum stress.

    PubMed

    Namba, Takushi; Tian, Fang; Chu, Kiki; Hwang, So-Young; Yoon, Kyoung Wan; Byun, Sanguine; Hiraki, Masatsugu; Mandinova, Anna; Lee, Sam W

    2013-10-31

    Resolved endoplasmic reticulum (ER) stress response is essential for intracellular homeostatic balance, but unsettled ER stress can lead to apoptosis. Here, we show that a proapoptotic p53 target, CDIP1, acts as a key signal transducer of ER-stress-mediated apoptosis. We identify B-cell-receptor-associated protein 31 (BAP31) as an interacting partner of CDIP1. Upon ER stress, CDIP1 is induced and enhances an association with BAP31 at the ER membrane. We also show that CDIP1 binding to BAP31 is required for BAP31 cleavage upon ER stress and for BAP31-Bcl-2 association. The recruitment of Bcl-2 to the BAP31-CDIP1 complex, as well as CDIP1-dependent truncated Bid (tBid) and caspase-8 activation, contributes to BAX oligomerization. Genetic knockout of CDIP1 in mice leads to impaired response to ER-stress-mediated apoptosis. Altogether, our data demonstrate that the CDIP1/BAP31-mediated regulation of mitochondrial apoptosis pathway represents a mechanism for establishing an ER-mitochondrial crosstalk for ER-stress-mediated apoptosis signaling.

  1. CSB ablation induced apoptosis is mediated by increased endoplasmic reticulum stress response

    PubMed Central

    Caputo, Manuela; Balzerano, Alessio; Arisi, Ivan; D’Onofrio, Mara; Brandi, Rossella; Bongiorni, Silvia; Brancorsini, Stefano; Frontini, Mattia; Proietti-De-Santis, Luca

    2017-01-01

    The DNA repair protein Cockayne syndrome group B (CSB) has been recently identified as a promising anticancer target. Suppression, by antisense technology, of this protein causes devastating effects on tumor cells viability, through a massive induction of apoptosis, while being non-toxic to non-transformed cells. To gain insights into the mechanisms underlying the pro-apoptotic effects observed after CSB ablation, global gene expression patterns were determined, to identify genes that were significantly differentially regulated as a function of CSB expression. Our findings revealed that response to endoplasmic reticulum stress and response to unfolded proteins were ranked top amongst the cellular processes affected by CSB suppression. The major components of the endoplasmic reticulum stress-mediated apoptosis pathway, including pro-apoptotic factors downstream of the ATF3-CHOP cascade, were dramatically up-regulated. Altogether our findings add new pieces to the understanding of CSB mechanisms of action and to the molecular basis of CS syndrome. PMID:28253359

  2. Endoplasmic reticulum stress in diabetes: New insights of clinical relevance.

    PubMed

    Balasubramanyam, Muthuswamy; Lenin, Raji; Monickaraj, Finny

    2010-04-01

    The endoplasmic reticulum (ER) is a cellular compartment responsible for multiple important cellular functions including the biosynthesis and folding of newly synthesized proteins destined for secretion, such as insulin. A myriad of pathological and physiological factors perturb ER function and cause dysregulation of ER homeostasis, leading to ER stress. Accumulating evidence suggests that ER stress plays a role in the pathogenesis of diabetes, contributing to pancreatic β-cell loss and insulin resistance. ER stress may also link obesity, inflammation and insulin resistance in type 2 diabetes. In this review, we address the transition from physiology to pathology, namely how and why the physiological UPR evolves to a proapoptotic ER stress response in diabetes and its complications. Special attention was given to elucidate how ER stress could explain some of the 'clinical paradoxes' such as secondary sulfonylurea failure, initial worsening of retinopathy during tight glycemic control, insulin resistance induced by protease inhibitors and other clinically relevant observations.

  3. The endoplasmic reticulum stress response: A link with tuberculosis?

    PubMed

    Cui, Yongyong; Zhao, Deming; Barrow, Paul Andrew; Zhou, Xiangmei

    2016-03-01

    Tuberculosis (TB) remains a major cause of mortality and morbidity in the worldwide. The endoplasmic-reticulum stress (ERS) response constitutes a cellular process that is triggered by mycobacterial infection that disturbs the folding of proteins in the endoplasmic reticulum (ER). The unfolded protein response (UPR) is induced to suspend the synthesis of early proteins and reduce the accumulation of unfolded- or misfolded proteins in the ER restoring normal physiological cell function. Prolonged or uncontrolled ERS leads to the activation of three signaling pathways (IRE1, PERK and ATF6) which directs the cell towards apoptosis. The absence of this process facilitates spread of the mycobacteria within the body. We summarize here recent advances in understanding the signaling pathway diversity governing ERS in relation to TB.

  4. Brain death is associated with endoplasmic reticulum stress and apoptosis in rat liver.

    PubMed

    Cao, S; Wang, T; Yan, B; Lu, Y; Zhao, Y; Zhang, S

    2014-12-01

    Cell death pathways initiated by stress on the endoplasmic reticulum (ER) have been implicated in a variety of common diseases, such as ischemia/reperfusion injury, diabetes, heart disease, and neurodegenerative disorders. However, the contribution of ER stress to apoptosis and liver injury after brain death is not known. In the present study, we found that brain death induces a variety of signature ER stress markers, including ER stress-specific X box-binding protein 1 and up-regulation of glucose-regulated protein 78. Furthermore, brain death causes up-regulation of C/EBP homologous protein and caspase-12. Consistent with this, terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling assay and transmission electron microscopy confirmed apoptosis in the liver after brain death. Taken together, the present study provides strong evidence supporting the presence and importance of ER stress and response in mediating brain death-induced apoptosis and liver injury.

  5. Endoplasmic reticulum stress in spinal and bulbar muscular atrophy: a potential target for therapy.

    PubMed

    Montague, Karli; Malik, Bilal; Gray, Anna L; La Spada, Albert R; Hanna, Michael G; Szabadkai, Gyorgy; Greensmith, Linda

    2014-07-01

    Spinal and bulbar muscular atrophy is an X-linked degenerative motor neuron disease caused by an abnormal expansion in the polyglutamine encoding CAG repeat of the androgen receptor gene. There is evidence implicating endoplasmic reticulum stress in the development and progression of neurodegenerative disease, including polyglutamine disorders such as Huntington's disease and in motor neuron disease, where cellular stress disrupts functioning of the endoplasmic reticulum, leading to induction of the unfolded protein response. We examined whether endoplasmic reticulum stress is also involved in the pathogenesis of spinal and bulbar muscular atrophy. Spinal and bulbar muscular atrophy mice that carry 100 pathogenic polyglutamine repeats in the androgen receptor, and develop a late-onset neuromuscular phenotype with motor neuron degeneration, were studied. We observed a disturbance in endoplasmic reticulum-associated calcium homeostasis in cultured embryonic motor neurons from spinal and bulbar muscular atrophy mice, which was accompanied by increased endoplasmic reticulum stress. Furthermore, pharmacological inhibition of endoplasmic reticulum stress reduced the endoplasmic reticulum-associated cell death pathway. Examination of spinal cord motor neurons of pathogenic mice at different disease stages revealed elevated expression of markers for endoplasmic reticulum stress, confirming an increase in this stress response in vivo. Importantly, the most significant increase was detected presymptomatically, suggesting that endoplasmic reticulum stress may play an early and possibly causal role in disease pathogenesis. Our results therefore indicate that the endoplasmic reticulum stress pathway could potentially be a therapeutic target for spinal and bulbar muscular atrophy and related polyglutamine diseases.

  6. Carbon monoxide-releasing molecules reverse leptin resistance induced by endoplasmic reticulum stress.

    PubMed

    Zheng, Min; Zhang, Qinggao; Joe, Yeonsoo; Kim, Seul-Ki; Uddin, Md Jamal; Rhew, Hyunyul; Kim, Taeksang; Ryter, Stefan W; Chung, Hun Taeg

    2013-04-01

    Leptin, a circulating hormone, regulates food intake and body weight. While leptin resistance represents a major cause of obesity, the underlying mechanisms remain unclear. Endoplasmic reticulum (ER) stress can contribute to leptin resistance. Carbon monoxide (CO), a gaseous molecule, exerts antiapoptotic and anti-inflammatory effects in animal models of tissue injury. We hypothesized that CO could inhibit leptin resistance during ER stress. Thapsigargin or tunicamycin was used to induce ER stress in human cells expressing the leptin receptor. These agents markedly inhibited leptin-induced STAT3 phosphorylation, confirming that ER stress induces leptin resistance. The CO-releasing molecule CORM-2 blocked the ER stress-dependent inhibition of leptin-induced STAT3 phosphorylation. CORM-2 treatment induced the phosphorylation of protein kinase R-like endoplasmic reticulum kinase (PERK), and eukaryotic translation initiation factor-2α and enhanced PERK phosphorylation during ER stress. Furthermore, CORM-2 inhibited X-box binding protein-1 expression, activating transcription factor-6 cleavage, and inositol-requiring enzyme (IRE)1α phosphorylation induced by ER stress. IRE1α knockdown rescued leptin resistance, whereas PERK knockdown blocked CO-dependent regulation of IRE1α. In vivo, CO inhalation normalized body weight in animals fed high-fat diets. Furthermore, CO modulated ER stress pathways and rescued leptin resistance in vivo. In conclusion, the pathological mechanism of leptin resistance may be ameliorated by the pharmacological application of CO.

  7. Interplay of endoplasmic reticulum stress and autophagy in neurodegenerative disorders.

    PubMed

    Cai, Yu; Arikkath, Jyothi; Yang, Lu; Guo, Ming-Lei; Periyasamy, Palsamy; Buch, Shilpa

    2016-01-01

    The common underlying feature of most neurodegenerative diseases such as Alzheimer disease (AD), prion diseases, Parkinson disease (PD), and amyotrophic lateral sclerosis (ALS) involves accumulation of misfolded proteins leading to initiation of endoplasmic reticulum (ER) stress and stimulation of the unfolded protein response (UPR). Additionally, ER stress more recently has been implicated in the pathogenesis of HIV-associated neurocognitive disorders (HAND). Autophagy plays an essential role in the clearance of aggregated toxic proteins and degradation of the damaged organelles. There is evidence that autophagy ameliorates ER stress by eliminating accumulated misfolded proteins. Both abnormal UPR and impaired autophagy have been implicated as a causative mechanism in the development of various neurodegenerative diseases. This review highlights recent advances in the field on the role of ER stress and autophagy in AD, prion diseases, PD, ALS and HAND with the involvement of key signaling pathways in these processes and implications for future development of therapeutic strategies.

  8. Pharmacological Modulators of Endoplasmic Reticulum Stress in Metabolic Diseases

    PubMed Central

    Jung, Tae Woo; Choi, Kyung Mook

    2016-01-01

    The endoplasmic reticulum (ER) is the principal organelle responsible for correct protein folding, a step in protein synthesis that is critical for the functional conformation of proteins. ER stress is a primary feature of secretory cells and is involved in the pathogenesis of numerous human diseases, such as certain neurodegenerative and cardiometabolic disorders. The unfolded protein response (UPR) is a defense mechanism to attenuate ER stress and maintain the homeostasis of the organism. Two major degradation systems, including the proteasome and autophagy, are involved in this defense system. If ER stress overwhelms the capacity of the cell’s defense mechanisms, apoptotic death may result. This review is focused on the various pharmacological modulators that can protect cells from damage induced by ER stress. The possible mechanisms for cytoprotection are also discussed. PMID:26840310

  9. Endoplasmic Reticulum Stress and Unfolded Protein Response in Cartilage Pathophysiology; Contributing Factors to Apoptosis and Osteoarthritis

    PubMed Central

    Hughes, Alexandria; Oxford, Alexandra E.; Tawara, Ken; Jorcyk, Cheryl L.; Oxford, Julia Thom

    2017-01-01

    Chondrocytes of the growth plate undergo apoptosis during the process of endochondral ossification, as well as during the progression of osteoarthritis. Although the regulation of this process is not completely understood, alterations in the precisely orchestrated programmed cell death during development can have catastrophic results, as exemplified by several chondrodystrophies which are frequently accompanied by early onset osteoarthritis. Understanding the mechanisms that underlie chondrocyte apoptosis during endochondral ossification in the growth plate has the potential to impact the development of therapeutic applications for chondrodystrophies and associated early onset osteoarthritis. In recent years, several chondrodysplasias and collagenopathies have been recognized as protein-folding diseases that lead to endoplasmic reticulum stress, endoplasmic reticulum associated degradation, and the unfolded protein response. Under conditions of prolonged endoplasmic reticulum stress in which the protein folding load outweighs the folding capacity of the endoplasmic reticulum, cellular dysfunction and death often occur. However, unfolded protein response (UPR) signaling is also required for the normal maturation of chondrocytes and osteoblasts. Understanding how UPR signaling may contribute to cartilage pathophysiology is an essential step toward therapeutic modulation of skeletal disorders that lead to osteoarthritis. PMID:28335520

  10. Endoplasmic Reticulum Stress and Unfolded Protein Response in Cartilage Pathophysiology; Contributing Factors to Apoptosis and Osteoarthritis.

    PubMed

    Hughes, Alexandria; Oxford, Alexandra E; Tawara, Ken; Jorcyk, Cheryl L; Oxford, Julia Thom

    2017-03-20

    Chondrocytes of the growth plate undergo apoptosis during the process of endochondral ossification, as well as during the progression of osteoarthritis. Although the regulation of this process is not completely understood, alterations in the precisely orchestrated programmed cell death during development can have catastrophic results, as exemplified by several chondrodystrophies which are frequently accompanied by early onset osteoarthritis. Understanding the mechanisms that underlie chondrocyte apoptosis during endochondral ossification in the growth plate has the potential to impact the development of therapeutic applications for chondrodystrophies and associated early onset osteoarthritis. In recent years, several chondrodysplasias and collagenopathies have been recognized as protein-folding diseases that lead to endoplasmic reticulum stress, endoplasmic reticulum associated degradation, and the unfolded protein response. Under conditions of prolonged endoplasmic reticulum stress in which the protein folding load outweighs the folding capacity of the endoplasmic reticulum, cellular dysfunction and death often occur. However, unfolded protein response (UPR) signaling is also required for the normal maturation of chondrocytes and osteoblasts. Understanding how UPR signaling may contribute to cartilage pathophysiology is an essential step toward therapeutic modulation of skeletal disorders that lead to osteoarthritis.

  11. Endoplasmic Reticulum Calcium, Stress and Cell-to-Cell Adhesion

    PubMed Central

    Mauro, Theodora

    2014-01-01

    Darier's Disease (DD) is caused by mutations in the endoplasmic reticulum (ER) Ca2+ ATPase ATP2A2 (protein SERCA2). Current treatment modalities are ineffective for many patients. This report shows that impaired SERCA2 function, both in DD keratinocytes and in normal keratinocytes treated with the SERCA2-inhibitor thapsigargin, depletes ER Ca2+ stores, leading to constitutive ER stress and increased sensitivity to ER stressors. ER stress, in turn, leads to abnormal cell-to-cell adhesion via impaired redistribution of desmoplakin, desmoglein 3, desmocollin 3 and E-cadherin to the plasma membrane. This report illustrates how ER Ca2+ depletion and the resulting ER stress are central to the pathogenesis of the disease. Additionally, the authors introduce a possible new therapeutic agent, Miglustat. PMID:24924761

  12. Endoplasmic reticulum stress: The cause and solution to Huntington's disease?

    PubMed

    Jiang, Yuwei; Chadwick, Sarah R; Lajoie, Patrick

    2016-10-01

    Accumulation of misfolded proteins is a hallmark of many human diseases, including several incurable neurological disorders, such as Huntington's disease (HD). In HD, expansion of a polyglutamine stretch within the first exon of the Huntingtin protein (Htt) leads to Htt misfolding, aberrant protein aggregation, and progressive appearance of disease symptoms. Several studies in various organisms (from yeast to humans) have identified the accumulation of misfolded secretory proteins in the endoplasmic reticulum (ER stress) as a crucial determinant of cellular toxicity in HD. In this review, we highlight the recent research linking HD to ER stress. We also discuss how the modulation of signaling pathways responsible for coping with misfolded protein accumulation in the ER may constitute attractive methods to reduce toxicity and identify new therapeutic targets for treatment of HD. This article is part of a Special Issue entitled SI:ER stress.

  13. Hydrogen sulfide, endoplasmic reticulum stress and alcohol mediated neurotoxicity.

    PubMed

    George, Akash K; Behera, Jyotirmaya; Kelly, Kimberly E; Zhai, Yuankun; Tyagi, Neetu

    2017-02-14

    Alcohol is one of the most socially accepted addictive drugs in modern society. Its abuse affects virtually all organ systems with the central nervous system (CNS) being particularly vulnerable to excessive alcohol exposure. Alcohol exposure also causes profound damage to both the adult and developing brain. Excessive alcohol consumption induces numerous pathophysiological stress responses, one of which is the endoplasmic reticulum (ER) stress response. Potential mechanisms that trigger the alcohol induced ER stress response are either directly or indirectly related to alcohol metabolism, which include toxic levels of acetaldehyde and homocysteine, oxidative stress and abnormal epigenetic modifications. Growing evidence suggests that H2S is the most recently recognized gasotransmitter with tremendous physiological protective functions against oxidative stress induced neurotoxicity. In this review we address the alcohol induced oxidative stress mediated ER stress and the role of H2S in its mitigation in the context of alcohol neurotoxicity. Interruption of ER stress triggers is anticipated to have therapeutic benefits for alcohol mediated diseases and disorders.

  14. Sertraline induces endoplasmic reticulum stress in hepatic cells.

    PubMed

    Chen, Si; Xuan, Jiekun; Couch, Letha; Iyer, Advait; Wu, Yuanfeng; Li, Quan-Zhen; Guo, Lei

    2014-08-01

    Sertraline is used for the treatment of depression, and is also used for the treatment of panic, obsessive-compulsive, and post-traumatic stress disorders. Previously, we have demonstrated that sertraline caused hepatic cytotoxicity, with mitochondrial dysfunction and apoptosis being underlying mechanisms. In this study, we used microarray and other biochemical and molecular analyses to identify endoplasmic reticulum (ER) stress as a novel molecular mechanism. HepG2 cells were exposed to sertraline and subjected to whole genome gene expression microarray analysis. Pathway analysis revealed that ER stress is among the significantly affected biological changes. We confirmed the increased expression of ER stress makers by real-time PCR and Western blots. The expression of typical ER stress markers such as PERK, IRE1α, and CHOP was significantly increased. To study better ER stress-mediated drug-induced liver toxicity; we established in vitro systems for monitoring ER stress quantitatively and efficiently, using Gaussia luciferase (Gluc) and secreted alkaline phosphatase (SEAP) as ER stress reporters. These in vitro systems were validated using well-known ER stress inducers. In these two reporter assays, sertraline inhibited the secretion of Gluc and SEAP. Moreover, we demonstrated that sertraline-induced apoptosis was coupled to ER stress and that the apoptotic effect was attenuated by 4-phenylbutyrate, a potent ER stress inhibitor. In addition, we showed that the MAP4K4-JNK signaling pathway contributed to the process of sertraline-induced ER stress. In summary, we demonstrated that ER stress is a mechanism of sertraline-induced liver toxicity.

  15. Chlorpyrifos induces endoplasmic reticulum stress in JEG-3 cells.

    PubMed

    Reyna, Luciana; Flores-Martín, Jésica; Ridano, Magali E; Panzetta-Dutari, Graciela M; Genti-Raimondi, Susana

    2017-04-01

    Chlorpyrifos (CPF) is an organophosphorous pesticide widely used in agricultural, industrial, and household applications. We have previously shown that JEG-3 cells are able to attenuate the oxidative stress induced by CPF through the adaptive activation of the Nrf2/ARE pathway. Considering that there is a relationship between oxidative stress and endoplasmic reticulum stress (ER), herein we investigated whether CPF also induces ER stress in JEG-3 cells. Cells were exposed to 50μM or 100μM CPF during 24h in conditions where cell viability was not altered. Western blot and PCR assays were used to explore the protein and mRNA levels of ER stress biomarkers, respectively. CPF induced an increase of the typical ER stress-related proteins, such as GRP78/BiP and IRE1α, a sensor for the unfolded protein response, as well as in phospho-eIF2α and XBP1 mRNA splicing. Additionally, CPF led to a decrease in p53 protein expression. The downregulation of p53 levels induced by CPF was partially blocked when cells were exposed to CPF in the presence of the proteasome inhibitor MG132. Altogether, these findings point out that CPF induces ER stress in JEG-3 cells; however these cells are able to attenuate it downregulating the levels of the pro-apoptotic protein p53.

  16. ATM deficiency induces oxidative stress and endoplasmic reticulum stress in astrocytes.

    PubMed

    Liu, Na; Stoica, George; Yan, Mingshan; Scofield, Virginia L; Qiang, Wenan; Lynn, William S; Wong, Paul K Y

    2005-12-01

    ATM kinase, the product of the ataxia telangiectasia mutated (Atm) gene, is activated by genomic damage. ATM plays a crucial role in cell growth and development. Here we report that primary astrocytes isolated from ATM-deficient mice grow slowly, become senescent, and die in culture. However, before reaching senescence, these primary Atm(-/-) astrocytes, like Atm(-/-) lymphocytes, show increased spontaneous DNA synthesis. These astrocytes also show markers of oxidative stress and endoplasmic reticulum (ER) stress, including increased levels of heat shock proteins (HSP70 and GRP78), malondialdehyde adducts, Cu/Zn superoxide dismutase, procaspase 12 cleavage, and redox-sensitive phosphorylation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2). In addition, HSP70 and ERK1/2 phosphorylation are upregulated in the cerebella of ATM-deficient mice. This increase in ERK1/2 phosphorylation is seen primarily in cerebellar astrocytes, or Bergmann glia, near degenerating Purkinje cells. ERK1/2 activation and astrogliosis are also found in other parts of the brain, for example, the cortex. We conclude that ATM deficiency induces intrinsic growth defects, oxidative stress, ER stress, and ERKs activation in astrocytes.

  17. GADD34 Keeps the mTOR Pathway Inactivated in Endoplasmic Reticulum Stress Related Autophagy

    PubMed Central

    Holczer, Marianna; Bánhegyi, Gábor; Kapuy, Orsolya

    2016-01-01

    The balance of protein synthesis and proteolysis (i.e. proteostasis) is maintained by a complex regulatory network in which mTOR (mechanistic target of rapamycin serine/threonine kinase) pathway and unfolded protein response are prominent positive and negative actors. The interplay between the two systems has been revealed; however the mechanistic details of this crosstalk are largely unknown. The aim of the present study was to investigate the elements of crosstalk during endoplasmic reticulum stress and to verify the key role of GADD34 in the connection with the mTOR pathway. Here, we demonstrate that a transient activation of autophagy is present in endoplasmic reticulum stress provoked by thapsigargin or tunicamycin, which is turned into apoptotic cell death. The transient phase can be characterized by the elevation of the autophagic marker LC3II/I, by mTOR inactivation, AMP-activated protein kinase activation and increased GADD34 level. The switch from autophagy to apoptosis is accompanied with the appearance of apoptotic markers, mTOR reactivation, AMP-activated protein kinase inactivation and a decrease in GADD34. Inhibition of autophagy by 3-methyladenine shortens the transient phase, while inhibition of mTOR by rapamycin or resveratrol prolongs it. Inhibition of GADD34 by guanabenz or transfection of the cells with siGADD34 results in down-regulation of autophagy-dependent survival and a quick activation of mTOR, followed by apoptotic cell death. The negative effect of GADD34 inhibition is diminished when guanabenz or siGADD34 treatment is combined with rapamycin or resveratrol addition. These data confirm that GADD34 constitutes a mechanistic link between endoplasmic reticulum stress and mTOR inactivation, therefore promotes cell survival during endoplasmic reticulum stress. PMID:27992581

  18. Endoplasmic reticulum stress response in yeast and humans

    PubMed Central

    Wu, Haoxi; Ng, Benjamin S. H.; Thibault, Guillaume

    2014-01-01

    Stress pathways monitor intracellular systems and deploy a range of regulatory mechanisms in response to stress. One of the best-characterized pathways, the UPR (unfolded protein response), is an intracellular signal transduction pathway that monitors ER (endoplasmic reticulum) homoeostasis. Its activation is required to alleviate the effects of ER stress and is highly conserved from yeast to human. Although metazoans have three UPR outputs, yeast cells rely exclusively on the Ire1 (inositol-requiring enzyme-1) pathway, which is conserved in all Eukaryotes. In general, the UPR program activates hundreds of genes to alleviate ER stress but it can lead to apoptosis if the system fails to restore homoeostasis. In this review, we summarize the major advances in understanding the response to ER stress in Sc (Saccharomyces cerevisiae), Sp (Schizosaccharomyces pombe) and humans. The contribution of solved protein structures to a better understanding of the UPR pathway is discussed. Finally, we cover the interplay of ER stress in the development of diseases. PMID:24909749

  19. HDAC Inhibitors and RECK Modulate Endoplasmic Reticulum Stress in Tumor Cells

    PubMed Central

    Chen, Yun; Tsai, Ya-Hui; Tseng, Sheng-Hong

    2017-01-01

    In the tumor microenvironment hypoxia and nutrient deprived states can induce endoplasmic reticulum (ER) stress. If ER stress is not relieved, the tumor cells may become apoptotic. Therefore, targeting ER homeostasis is a potential strategy for cancer treatment. Various chemotherapeutic agents including histone deacetylase (HDAC) inhibitors can induce ER stress to cause cell death in cancers. Some HDAC inhibitors can prevent HDAC from binding to the specificity protein 1-binding site of the promoter of reversion-inducing cysteine-rich protein with Kazal motifs (RECK) and up-regulate RECK expression. Up-regulation of RECK expression by HDAC inhibitors has been observed in various cancer types. RECK is a tumor and metastasis suppressor gene and is critical for regulating tumor cell invasiveness and metastasis. RECK also modulates ER stress via binding to and sequestering glucose-regulated protein 78 protein, so that the transmembrane sensors, such as protein kinase RNA-like ER kinase are released to activate eukaryotic translational initiation factor 2α phosphorylation and enhance ER stress. Therefore, HDAC inhibitors may directly induce ER stress or indirectly induce this stress by up-regulating RECK in cancer cells. PMID:28134767

  20. The signaling mechanisms of hippocampal endoplasmic reticulum stress affecting neuronal plasticity-related protein levels in high fat diet-induced obese rats and the regulation of aerobic exercise.

    PubMed

    Cai, Ming; Wang, Hong; Li, Jing-Jing; Zhang, Yun-Li; Xin, Lei; Li, Feng; Lou, Shu-Jie

    2016-10-01

    High fat diet (HFD)-induced obesity has been shown to reduce the levels of neuronal plasticity-related proteins, specifically brain-derived neurotrophic factor (BDNF) and synaptophysin (SYN), in the hippocampus. However, the underlying mechanisms are not fully clear. Endoplasmic reticulum stress (ERS) has been reported to play a key role in regulating gene expression and protein production by affecting stress signaling pathways and ER functions of protein folding and post-translational modification in peripheral tissues of obese rodent models. Additionally, HFD that is associated with hyperglycemia could induce hippocampal ERS, thus impairing insulin signaling and cognitive health in HFD mice. One goal of this study was to determine whether hyperglycemia and hyperlipidemia could cause hippocampal ERS in HFD-induced obese SD rats, and explore the potential mechanisms of ERS regulating hippocampal BDNF and SYN proteins production. Additionally, although regular aerobic exercise could reduce central inflammation and elevate hippocampal BDNF and SYN levels in obese rats, the regulated mechanisms are poorly understood. Nrf2-HO-1 pathways play roles in anti-ERS, anti-inflammation and anti-apoptosis in peripheral tissues. Therefore, the other goal of this study was to determine whether aerobic exercise could activate Nrf2-HO-1 in hippocampus to alleviate obesity-induced hippocampal ERS, which would lead to increased BDNF and SYN levels. Male SD rats were fed on HFD for 8weeks to establish the obese model. Then, 8weeks of aerobic exercise treadmill intervention was arranged for the obese rats. Results showed that HFD-induced obesity caused hyperglycemia and hyperlipidemia, and significantly promoted hippocampal glucose transporter 3 (GLUT3) and fatty acid transport protein 1 (FATP1) protein expression. These results were associated with the activation of hippocampal ERS and ERS-mediated apoptosis. At the same time, we found that excessive hippocampal ERS not only

  1. Endoplasmic reticulum stress: a novel mechanism and therapeutic target for cardiovascular diseases

    PubMed Central

    Liu, Mei-qing; Chen, Zhe; Chen, Lin-xi

    2016-01-01

    Endoplasmic reticulum is a principal organelle responsible for folding, post-translational modifications and transport of secretory, luminal and membrane proteins, thus palys an important rale in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) is a condition that is accelerated by accumulation of unfolded/misfolded proteins after endoplasmic reticulum environment disturbance, triggered by a variety of physiological and pathological factors, such as nutrient deprivation, altered glycosylation, calcium depletion, oxidative stress, DNA damage and energy disturbance, etc. ERS may initiate the unfolded protein response (UPR) to restore cellular homeostasis or lead to apoptosis. Numerous studies have clarified the link between ERS and cardiovascular diseases. This review focuses on ERS-associated molecular mechanisms that participate in physiological and pathophysiological processes of heart and blood vessels. In addition, a number of drugs that regulate ERS was introduced, which may be used to treat cardiovascular diseases. This review may open new avenues for studying the pathogenesis of cardiovascular diseases and discovering novel drugs targeting ERS. PMID:26838072

  2. Naltrexone attenuates endoplasmic reticulum stress induced hepatic injury in mice.

    PubMed

    Moslehi, A; Nabavizadeh, F; Nabavizadeh, Fatemeh; Dehpour, A R; Dehpou, A R; Tavanga, S M; Hassanzadeh, G; Zekri, A; Nahrevanian, H; Sohanaki, H

    2014-09-01

    Endoplasmic reticulum (ER) stress provides abnormalities in insulin action, inflammatory responses, lipoprotein B100 degradation and hepatic lipogenesis. Excess accumulation of triglyceride in hepatocytes may also lead to disorders such as non-alcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Opioid peptides are involved in triglyceride and cholesterol dysregulation, inflammation and cell death. In this study, we evaluated Naltrexone effects on ER stress induced liver injury. To do so, C57/BL6 mice received saline, DMSO and Naltrexone, as control groups. ER stress was induced by tunicamycin (TM) injection. Naltrexone was given before TM administration. Liver blood flow and biochemical serum analysis were measured. Histopathological evaluations, TNF-α measurement and Real-time RT-PCR were also performed. TM challenge provokes steatosis, cellular ballooning and lobular inflammation which significantly reduced in Naltrexone treated animals. ALT, AST and TNF-α increased in the TM group and improved in the Naltrexone plus TM group. Triglyceride and cholesterol levels decreased in TM treated mice with no increase in Naltrexone treated animals. In the Naltrexone plus TM group, gene expression of Bax/Bcl-2 ratio and caspase3 significantly lowered compared with the TM group. In this study, we found that Naltrexone had a notable alleviating role in ER stress induced steatosis and liver injury.

  3. Mollugin induces apoptosis in human Jurkat T cells through endoplasmic reticulum stress-mediated activation of JNK and caspase-12 and subsequent activation of mitochondria-dependent caspase cascade regulated by Bcl-xL

    SciTech Connect

    Kim, Sun Mi; Park, Hae Sun; Jun, Do Youn; Woo, Hyun Ju; Woo, Mi Hee; Yang, Chae Ha; Kim, Young Ho

    2009-12-01

    Exposure of Jurkat T cells to mollugin (15-30 muM), purified from the roots of Rubia cordifolia L., caused cytotoxicity and apoptotic DNA fragmentation along with mitochondrial membrane potential disruption, mitochondrial cytochrome c release, phosphorylation of c-Jun N-terminal kinase (JNK), activation of caspase-12, -9, -7, -3, and -8, cleavage of FLIP and Bid, and PARP degradation, without accompanying necrosis. While these mollugin-induced cytotoxicity and apoptotic events including activation of caspase-8 and mitochondria-dependent activation of caspase cascade were completely prevented by overexpression of Bcl-xL, the activation of JNK and caspase-12 was prevented to much lesser extent. Pretreatment of the cells with the pan-caspase inhibitor (z-VAD-fmk), the caspase-9 inhibitor (z-LEHD-fmk), the caspase-3 inhibitor (z-DEVD-fmk) or the caspase-12 inhibitor (z-ATAD-fmk) at the minimal concentration to prevent mollugin-induced apoptosis appeared to completely block the activation of caspase-7 and -8, and PARP degradation, but failed to block the activation of caspase-9 and -3 with allowing a slight enhancement in the level of JNK phosphorylation. Both FADD-positive wild-type Jurkat clone A3 and FADD-deficient Jurkat clone I2.1 exhibited a similar susceptibility to the cytotoxicity of mollugin, excluding involvement of Fas/FasL system in triggering mollugin-induced apoptosis. Normal peripheral T cells were more refractory to the cytotoxicity of mollugin than were Jurkat T cells. These results demonstrated that mollugin-induced cytotoxicity in Jurkat T cells was mainly attributable to apoptosis provoked via endoplasmic reticulum (ER) stress-mediated activation of JNK and caspase-12, and subsequent mitochondria-dependent activation of caspase-9 and -3, leading to activation of caspase-7 and -8, which could be regulated by Bcl-xL.

  4. Endoplasmic reticulum stress: key promoter of rosacea pathogenesis.

    PubMed

    Melnik, Bodo C

    2014-12-01

    Recent scientific interest in the pathogenesis of rosacea focuses on abnormally high facial skin levels of cathelicidin and the trypsin-like serine protease kallikrein 5 (KLK5) that cleaves the cathelicidin precursor protein into the bioactive fragment LL-37, which exerts crucial proinflammatory, angiogenic and antimicrobial activities. Furthermore, increased expression of toll-like receptor 2 (TLR2) has been identified in rosacea skin supporting the participation of the innate immune system. Notably, TLRs are expressed on sensory neurons and increase neuronal excitability linking TLR signalling to the transmission of neuroinflammatory responses. It is the intention of this viewpoint to present a unifying concept that links all known clinical trigger factors of rosacea such as UV irradiation, heat, skin irritants and special foods to one converging point: enhanced endoplasmic reticulum (ER) stress that activates the unfolded protein response (UPR). ER stress via upregulation of transcription factor ATF4 increases TLR2 expression, resulting in enhanced production of cathelicidin and KLK5 mediating downstream proinflammatory, angiogenic and antimicrobial signalling. The presented concept identifies rosacea trigger factors as environmental stressors that enhance the skin's ER stress response. Exaggerated cutaneous ER stress that stimulates the TLR2-driven inflammatory response may involve sebocytes, keratinocytes, monocyte-macrophages and sensory cutaneous neurons. Finally, all antirosacea drugs are proposed to attenuate the ER stress signalling cascade at some point. Overstimulated ER stress signalling may have evolutionarily evolved as a compensatory mechanism to balance impaired vitamin D-driven LL-37-mediated antimicrobial defenses due to lower exposure of UV-B irradiation of the northern Celtic population.

  5. Endoplasmic reticulum stress-induced apoptosis in the penumbra aggravates secondary damage in rats with traumatic brain injury

    PubMed Central

    Sun, Guo-zhu; Gao, Fen-fei; Zhao, Zong-mao; Sun, Hai; Xu, Wei; Wu, Li-wei; He, Yong-chang

    2016-01-01

    Neuronal apoptosis is mediated by intrinsic and extrinsic signaling pathways such as the membrane-mediated, mitochondrial, and endoplasmic reticulum stress pathways. Few studies have examined the endoplasmic reticulum-mediated apoptosis pathway in the penumbra after traumatic brain injury, and it remains unclear whether endoplasmic reticulum stress can activate the caspase-12-dependent apoptotic pathway in the traumatic penumbra. Here, we established rat models of fluid percussion-induced traumatic brain injury and found that protein expression of caspase-12, caspase-3 and the endoplasmic reticulum stress marker 78 kDa glucose-regulated protein increased in the traumatic penumbra 6 hours after injury and peaked at 24 hours. Furthermore, numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells in the traumatic penumbra also reached peak levels 24 hours after injury. These findings suggest that caspase-12-mediated endoplasmic reticulum-related apoptosis is activated in the traumatic penumbra, and may play an important role in the pathophysiology of secondary brain injury. PMID:27651773

  6. Selenoprotein K modulate intracellular free Ca(2+) by regulating expression of calcium homoeostasis endoplasmic reticulum protein.

    PubMed

    Wang, Chao; Li, Ruimin; Huang, Yalan; Wang, Miao; Yang, Fan; Huang, Dana; Wu, Chunli; Li, Yue; Tang, Yijun; Zhang, Renli; Cheng, Jinquan

    2017-03-18

    Selenoprotein K (SelK) is an 11-kDa selenoprotein, which may be involved in the regulation of oxidative stress, endoplasmic reticulum (ER) stress and immune response. To explore the function of SelK in the process of immune response, several short-hairpin RNAs (shRNA) were designed for the construction of recombinant plasmids to down-regulate the expression of SelK gene in vitro. These shRNAs specifically and efficiently interfered with the expression of SelK at both mRNA and protein levels. The expression of calcium homoeostasis endoplasmic reticulum protein (CHERP) and the intracellular free Ca(2+) concentration were significantly down-regulated in anti-CD3 stimulated SelK-knockdown cells. The expression of Interleukin 2 receptor alpha chain (IL-2Rα) and the secretion of Interleukin 4 (IL-4), which play a significant role in the process of T cell activation and proliferation, were also reduced in SelK-knockdown cells. Selenomethionine (Se-Met) at an optimum concentration of 5 μM could up-regulate SelK expression and reverse the change of the expression of CHERP and the intracellular free calcium caused by SelK-knockdown. These results hereby imply SelK may regulate the release of Ca(2+) by CHERP and play an important role in the proliferation and differentiation of T cell by TCR stimulation.

  7. Trichoplein/mitostatin regulates endoplasmic reticulum-mitochondria juxtaposition.

    PubMed

    Cerqua, Cristina; Anesti, Vassiliki; Pyakurel, Aswin; Liu, Dan; Naon, Deborah; Wiche, Gerhard; Baffa, Raffaele; Dimmer, Kai S; Scorrano, Luca

    2010-11-01

    Trichoplein/mitostatin (TpMs) is a keratin-binding protein that partly colocalizes with mitochondria and is often downregulated in epithelial cancers, but its function remains unclear. In this study, we report that TpMs regulates the tethering between mitochondria and endoplasmic reticulum (ER) in a Mitofusin 2 (Mfn2)-dependent manner. Subcellular fractionation and immunostaining show that TpMs is present at the interface between mitochondria and ER. The expression of TpMs leads to mitochondrial fragmentation and loosens tethering with ER, whereas its silencing has opposite effects. Functionally, the reduced tethering by TpMs inhibits apoptosis by Ca(2+)-dependent stimuli that require ER-mitochondria juxtaposition. Biochemical and genetic evidence support a model in which TpMs requires Mfn2 to modulate mitochondrial shape and tethering. Thus, TpMs is a new regulator of mitochondria-ER juxtaposition.

  8. Insulin Dissociates the Effects of Liver X Receptor on Lipogenesis, Endoplasmic Reticulum Stress, and Inflammation*

    PubMed Central

    Sun, Xiaowei; Haas, Mary E.; Miao, Ji; Mehta, Abhiruchi; Graham, Mark J.; Crooke, Rosanne M.; de Barros, Jean-Paul Pais; Wang, Jian-Guo; Aikawa, Masanori; Masson, David; Biddinger, Sudha B.

    2016-01-01

    Diabetes is characterized by increased lipogenesis as well as increased endoplasmic reticulum (ER) stress and inflammation. The nuclear hormone receptor liver X receptor (LXR) is induced by insulin and is a key regulator of lipid metabolism. It promotes lipogenesis and cholesterol efflux, but suppresses endoplasmic reticulum stress and inflammation. The goal of these studies was to dissect the effects of insulin on LXR action. We used antisense oligonucleotides to knock down Lxrα in mice with hepatocyte-specific deletion of the insulin receptor and their controls. We found, surprisingly, that knock-out of the insulin receptor and knockdown of Lxrα produced equivalent, non-additive effects on the lipogenic genes. Thus, insulin was unable to induce the lipogenic genes in the absence of Lxrα, and LXRα was unable to induce the lipogenic genes in the absence of insulin. However, insulin was not required for LXRα to modulate the phospholipid profile, or to suppress genes in the ER stress or inflammation pathways. These data show that insulin is required specifically for the lipogenic effects of LXRα and that manipulation of the insulin signaling pathway could dissociate the beneficial effects of LXR on cholesterol efflux, inflammation, and ER stress from the negative effects on lipogenesis. PMID:26511317

  9. Endoplasmic reticulum stress in the peripheral nervous system is a significant driver of neuropathic pain.

    PubMed

    Inceoglu, Bora; Bettaieb, Ahmed; Trindade da Silva, Carlos A; Lee, Kin Sing Stephen; Haj, Fawaz G; Hammock, Bruce D

    2015-07-21

    Despite intensive effort and resulting gains in understanding the mechanisms underlying neuropathic pain, limited success in therapeutic approaches have been attained. A recently identified, nonchannel, nonneurotransmitter therapeutic target for pain is the enzyme soluble epoxide hydrolase (sEH). The sEH degrades natural analgesic lipid mediators, epoxy fatty acids (EpFAs), therefore its inhibition stabilizes these bioactive mediators. Here we demonstrate the effects of EpFAs on diabetes induced neuropathic pain and define a previously unknown mechanism of pain, regulated by endoplasmic reticulum (ER) stress. The activation of ER stress is first quantified in the peripheral nervous system of type I diabetic rats. We demonstrate that both pain and markers of ER stress are reversed by a chemical chaperone. Next, we identify the EpFAs as upstream modulators of ER stress pathways. Chemical inducers of ER stress invariably lead to pain behavior that is reversed by a chemical chaperone and an inhibitor of sEH. The rapid occurrence of pain behavior with inducers, equally rapid reversal by blockers and natural incidence of ER stress in diabetic peripheral nervous system (PNS) argue for a major role of the ER stress pathways in regulating the excitability of the nociceptive system. Understanding the role of ER stress in generation and maintenance of pain opens routes to exploit this system for therapeutic purposes.

  10. PERK-opathies: An Endoplasmic Reticulum Stress Mechanism Underlying Neurodegeneration.

    PubMed

    Bell, Michelle C; Meier, Shelby E; Ingram, Alexandria L; Abisambra, Jose F

    2016-01-01

    The unfolded protein response (UPR) plays a vital role in maintaining cell homeostasis as a consequence of endoplasmic reticulum (ER) stress. However, prolonged UPR activity leads to cell death. This time-dependent dual functionality of the UPR represents the adaptive and cytotoxic pathways that result from ER stress. Chronic UPR activation in systemic and neurodegenerative diseases has been identified as an early sign of cellular dyshomeostasis. The Protein Kinase R-like ER Kinase (PERK) pathway is one of three major branches in the UPR, and it is the only one to modulate protein synthesis as an adaptive response. The specific identification of prolonged PERK activity has been correlated with the progression of disorders such as diabetes, Alzheimer's disease, and cancer, suggesting that PERK plays a role in the pathology of these disorders. For the first time, the term "PERK-opathies" is used to group these diseases in which PERK mediates detriment to the cell culminating in chronic disorders. This article reviews the literature documenting links between systemic disorders with the UPR, but with a specific emphasis on the PERK pathway. Then, articles reporting links between the UPR, and more specifically PERK, and neurodegenerative disorders are presented. Finally, a therapeutic perspective is discussed, where PERK interventions could be potential remedies for cellular dysfunction in chronic neurodegenerative disorders.

  11. Endoplasmic reticulum stress activation during total knee arthroplasty

    PubMed Central

    Hocker, Austin D; Boileau, Ryan M; Lantz, Brick A; Jewett, Brian A; Gilbert, Jeffrey S; Dreyer, Hans C

    2013-01-01

    Total knee arthroplasty (TKA) is the most common remediation for knee pain from osteoarthritis (OA) and is performed 650,000 annually in the U.S. A tourniquet is commonly used during TKA which causes ischemia and reperfusion (I/R) to the lower limb but the effects of I/R on muscle are not fully understood. Previous reports suggest upregulation of cell stress and catabolism and downregulation of markers of cap-dependent translation during and after TKA. I/R has also been shown to cause endoplasmic reticulum (ER) stress and induce the unfolded protein response (UPR). We hypothesized that the UPR would be activated in response to ER stress during TKA. We obtained muscle biopsies from the vastus lateralis at baseline, before TKA; at maximal ischemia, prior to tourniquet deflation; and during reperfusion in the operating room. Phosphorylation of 4E-BP1 and AKT decreased during ischemia (−28%, P < 0.05; −20%, P < 0.05, respectively) along with an increase in eIF2α phosphorylation (64%, P < 0.05) suggesting decreased translation initiation. Cleaved ATF6 protein increased in ischemia (39%, P = 0.056) but returned to baseline during reperfusion. CASP3 activation increased during reperfusion compared to baseline (23%, P < 0.05). XBP1 splicing assays revealed an increase in spliced transcript during ischemia (31%, P < 0.05) which diminished during reperfusion. These results suggest that in response to I/R during TKA all three branches of the ER stress response are activated. PMID:24159375

  12. The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease

    DTIC Science & Technology

    2016-07-01

    AWARD NUMBER: W81XWH-14-1-0203 TITLE: The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease PRINCIPAL...1 July 2015- 30 June 2016 4. TITLE AND SUBTITLE The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease 5a...We hypothesize that ER stress induced by glucose in diabetes promotes diabetic CKD through CRT stimulation of TGF-beta-dependent calcium/NFAT

  13. The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease

    DTIC Science & Technology

    2015-07-01

    1 AWARD NUMBER: W81XWH-14-1-0203 TITLE: The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease PRINCIPAL...COVERED 07/01/2014-06/30/2015 4. TITLE AND SUBTITLE The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease 5a...NUMBER(S) 13. SUPPLEMENTARY NOTES 14. ABSTRACT We hypothesize that ER stress induced by glucose in diabetes promotes diabetic CKD through CRT stimulation

  14. Prodigiosin activates endoplasmic reticulum stress cell death pathway in human breast carcinoma cell lines

    SciTech Connect

    Pan, Mu-Yun; Shen, Yuh-Chiang; Lu, Chien-Hsing; Yang, Shu-Yi; Ho, Tsing-Fen; Peng, Yu-Ta; Chang, Chia-Che

    2012-12-15

    Prodigiosin is a bacterial tripyrrole pigment with potent cytotoxicity against diverse human cancer cell lines. Endoplasmic reticulum (ER) stress is initiated by accumulation of unfolded or misfolded proteins in the ER lumen and may induce cell death when irremediable. In this study, the role of ER stress in prodigiosin-induced cytotoxicity was elucidated for the first time. Comparable to the ER stress inducer thapsigargin, prodigiosin up-regulated signature ER stress markers GRP78 and CHOP in addition to activating the IRE1, PERK and ATF6 branches of the unfolded protein response (UPR) in multiple human breast carcinoma cell lines, confirming prodigiosin as an ER stress inducer. Prodigiosin transcriptionally up-regulated CHOP, as evidenced by its promoting effect on the CHOP promoter activity. Of note, knockdown of CHOP effectively lowered prodigiosin's capacity to evoke PARP cleavage, reduce cell viability and suppress colony formation, highlighting an essential role of CHOP in prodigiosin-induced cytotoxic ER stress response. In addition, prodigiosin down-regulated BCL2 in a CHOP-dependent manner. Importantly, restoration of BCL2 expression blocked prodigiosin-induced PARP cleavage and greatly enhanced the survival of prodigiosin-treated cells, suggesting that CHOP-dependent BCL2 suppression mediates prodigiosin-elicited cell death. Moreover, pharmacological inhibition of JNK by SP600125 or dominant-negative blockade of PERK-mediated eIF2α phosphorylation impaired prodigiosin-induced CHOP up-regulation and PARP cleavage. Collectively, these results identified ER stress-mediated cell death as a mode-of-action of prodigiosin's tumoricidal effect. Mechanistically, prodigiosin engages the IRE1–JNK and PERK–eIF2α branches of the UPR signaling to up-regulate CHOP, which in turn mediates BCL2 suppression to induce cell death. Highlights: ► Prodigiosin is a bacterial tripyrrole pigment with potent anticancer effect. ► Prodigiosin is herein identified as an

  15. Acrolein cytotoxicity in hepatocytes involves endoplasmic reticulum stress, mitochondrial dysfunction and oxidative stress

    SciTech Connect

    Mohammad, Mohammad K.; Avila, Diana; Zhang, Jingwen; Barve, Shirish; Arteel, Gavin; McClain, Craig; Joshi-Barve, Swati

    2012-11-15

    Acrolein is a common environmental, food and water pollutant and a major component of cigarette smoke. Also, it is produced endogenously via lipid peroxidation and cellular metabolism of certain amino acids and drugs. Acrolein is cytotoxic to many cell types including hepatocytes; however the mechanisms are not fully understood. We examined the molecular mechanisms underlying acrolein hepatotoxicity in primary human hepatocytes and hepatoma cells. Acrolein, at pathophysiological concentrations, caused a dose-dependent loss of viability of hepatocytes. The death was apoptotic at moderate and necrotic at high concentrations of acrolein. Acrolein exposure rapidly and dramatically decreased intracellular glutathione and overall antioxidant capacity, and activated the stress-signaling MAP-kinases JNK, p42/44 and p38. Our data demonstrate for the first time in human hepatocytes, that acrolein triggered endoplasmic reticulum (ER) stress and activated eIF2α, ATF-3 and -4, and Gadd153/CHOP, resulting in cell death. Notably, the protective/adaptive component of ER stress was not activated, and acrolein failed to up-regulate the protective ER-chaperones, GRP78 and GRP94. Additionally, exposure to acrolein disrupted mitochondrial integrity/function, and led to the release of pro-apoptotic proteins and ATP depletion. Acrolein-induced cell death was attenuated by N-acetyl cysteine, phenyl-butyric acid, and caspase and JNK inhibitors. Our data demonstrate that exposure to acrolein induces a variety of stress responses in hepatocytes, including GSH depletion, oxidative stress, mitochondrial dysfunction and ER stress (without ER-protective responses) which together contribute to acrolein toxicity. Our study defines basic mechanisms underlying liver injury caused by reactive aldehyde pollutants such as acrolein. -- Highlights: ► Human primary hepatocytes and cultured cell lines are used. ► Multiple cell death signaling pathways are activated by acrolein. ► Novel finding of

  16. Endoplasmic Reticulum Stress in Age-Related Macular Degeneration: Trigger for Neovascularization

    PubMed Central

    Salminen, Antero; Kauppinen, Anu; Hyttinen, Juha MT; Toropainen, Elisa; Kaarniranta, Kai

    2010-01-01

    Age-related macular degeneration (AMD) can be classified into two main categories: the atrophic, dry form and the exudative, wet form. The crucial difference between dry and wet AMD is the development of choroidal neovascularization in wet AMD. One fundamental cause of the neovascularization is the increased expression of VEGF (vascular endothelial growth factor) in retinal pigment epithelial cells. Progression of AMD is linked to augmentation of cellular stress, for example, oxidative stress, proteotoxic stress, inflammation and hypoxia. All these conditions can trigger stress in endoplasmic reticulum (ER), which maintains protein quality control in cells. ER stress induces the unfolded protein response (UPR) via IRE1 (inositol-requiring protein-1), PERK (protein kinase RNA-like ER kinase) and ATF6 (activating transcription factor-6) transducers. UPR signaling is a double-edged sword, that is, it can restore cellular homeostasis as far as possible, but ultimately may lead to chronic, overwhelming stress that can cause apoptotic cell death. Interestingly, ER stress is a well-known inducer of angiogenesis in cancer. Moreover, stress conditions associated with the progress of AMD can induce the expression of VEGF. We discuss the role of ER stress in the regulation of neovascularization and the conversion of dry AMD to its wet, detrimental counterpart. PMID:20683548

  17. Rtn1a-Mediated Endoplasmic Reticulum Stress in Podocyte Injury and Diabetic Nephropathy.

    PubMed

    Fan, Ying; Zhang, Jing; Xiao, Wenzhen; Lee, Kyung; Li, Zhengzhe; Wen, Jiejun; He, Li; Gui, Dingkun; Xue, Rui; Jian, Guihua; Sheng, Xiaohua; He, John Cijiang; Wang, Niansong

    2017-03-23

    We previously reported a critical role of reticulon (RTN) 1A in mediating endoplasmic reticulum (ER) stress in kidney tubular cells and the expression of RTN1A correlates with the renal function and the severity of kidney injury in patients with diabetic nephropathy (DN). Here, we determined the roles of RTN1A and ER stress in podocyte injury and DN. We used db/db mice with early unilateral nephrectomy (Unx) as a murine model of progressive DN and treated mice with tauroursodeoxycholic acid (TUDCA), a specific inhibitor of ER stress. We found increased expression of RTN1A and ER stress markers in the kidney of db/db-Unx mice. Treatment of TUDCA not only attenuated proteinuria and kidney histological changes, but also ameliorated podocyte and glomeruli injury in diabetic mice, which were associated with reduction of RTN1A and ER stress marker expression in the podocytes of TUDCA-treated mice. In vitro, we showed RTN1A mediates albumin-induced ER stress and apoptosis in human podocytes. A positive feedback loop between RTN1A and CHOP was found leading to an enhanced ER stress in podocytes. Our data suggest that ER stress plays a major role in podocyte injury in DN and RTN1A might be a key regulator of ER stress in podocytes.

  18. Valsartan protects HK-2 cells from contrast media-induced apoptosis by inhibiting endoplasmic reticulum stress.

    PubMed

    Peng, Ping-An; Wang, Le; Ma, Qian; Xin, Yi; Zhang, Ou; Han, Hong-Ya; Liu, Xiao-Li; Ji, Qing-Wei; Zhou, Yu-Jie; Zhao, Ying-Xin

    2015-12-01

    Contrast-induced acute kidney injury (CI-AKI) is associated with increasing in-hospital and long-term adverse clinical outcomes in high-risk patients undergoing percutaneous coronary intervention (PCI). Contrast media (CM)-induced renal tubular cell apoptosis is reported to participate in this process by activating endoplasmic reticulum (ER) stress. An angiotensin II type 1 receptor (AT1R) antagonist can alleviate ER stress-induced renal apoptosis in streptozotocin (STZ)-induced diabetic mice and can reduce CM-induced renal apoptosis by reducing oxidative stress and reversing the enhancement of bax mRNA and the reduction of bcl-2 mRNA, but the effect of the AT1R blocker on ER stress in the pathogenesis of CI-AKI is still unknown. In this study, we explored the effect of valsartan on meglumine diatrizoate-induced human renal tubular cell apoptosis by measuring changes in ER stress-related biomarkers. The results showed that meglumine diatrizoate caused significant cell apoptosis by up-regulating the expression of ER stress markers, including glucose-regulated protein 78 (GRP78), activating transcription factor 4 (ATF4), CCAAT/enhancer-binding protein-homologous protein (CHOP) and caspase 12, in a time- and dose-dependent manner, which could be alleviated by preincubation with valsartan. In conclusion, valsartan had a potential nephroprotective effect on meglumine diatrizoate-induced renal cell apoptosis by inhibiting ER stress.

  19. Respiratory metabolism and calorie restriction relieve persistent endoplasmic reticulum stress induced by calcium shortage in yeast

    PubMed Central

    Busti, Stefano; Mapelli, Valeria; Tripodi, Farida; Sanvito, Rossella; Magni, Fulvio; Coccetti, Paola; Rocchetti, Marcella; Nielsen, Jens; Alberghina, Lilia; Vanoni, Marco

    2016-01-01

    Calcium homeostasis is crucial to eukaryotic cell survival. By acting as an enzyme cofactor and a second messenger in several signal transduction pathways, the calcium ion controls many essential biological processes. Inside the endoplasmic reticulum (ER) calcium concentration is carefully regulated to safeguard the correct folding and processing of secretory proteins. By using the model organism Saccharomyces cerevisiae we show that calcium shortage leads to a slowdown of cell growth and metabolism. Accumulation of unfolded proteins within the calcium-depleted lumen of the endoplasmic reticulum (ER stress) triggers the unfolded protein response (UPR) and generates a state of oxidative stress that decreases cell viability. These effects are severe during growth on rapidly fermentable carbon sources and can be mitigated by decreasing the protein synthesis rate or by inducing cellular respiration. Calcium homeostasis, protein biosynthesis and the unfolded protein response are tightly intertwined and the consequences of facing calcium starvation are determined by whether cellular energy production is balanced with demands for anabolic functions. Our findings confirm that the connections linking disturbance of ER calcium equilibrium to ER stress and UPR signaling are evolutionary conserved and highlight the crucial role of metabolism in modulating the effects induced by calcium shortage. PMID:27305947

  20. Inhibin beta E is upregulated by drug-induced endoplasmic reticulum stress as a transcriptional target gene of ATF4

    SciTech Connect

    Brüning, Ansgar Matsingou, Christina; Brem, German Johannes; Rahmeh, Martina; Mylonas, Ioannis

    2012-10-15

    Inhibins and activins are gonadal peptide hormones of the transforming growth factor-β super family with important functions in the reproductive system. By contrast, the recently identified inhibin βE subunit, primarily expressed in liver cells, appears to exert functions unrelated to the reproductive system. Previously shown downregulation of inhibin βE in hepatoma cells and anti-proliferative effects of ectopic inhibin βE overexpression indicated growth-regulatory effects of inhibin βE. We observed a selective re-expression of the inhibin βE subunit in HepG2 hepatoblastoma cells, MCF7 breast cancer cells, and HeLa cervical cancer cells under endoplasmic reticulum stress conditions induced by tunicamycin, thapsigargin, and nelfinavir. Analysis of XPB1 splicing and ATF4 activation revealed that inhibin βE re-expression was associated with induction of the endoplasmic reticulum stress reaction by these drugs. Transfection of an ATF4 expression plasmid specifically induced inhibin βE expression in HeLa cells and indicates inhibin βE as a hitherto unidentified target gene of ATF4, a key transcription factor of the endoplasmic reticulum stress response. Therefore, the inhibin βE subunit defines not only a new player but also a possible new marker for drug-induced endoplasmic reticulum stress. -- Highlights: ► Endoplasmic reticulum stress induces inhibin beta E expression. ► Inhibin beta E is regulated by the transcription factor ATF4. ► Inhibin beta E expression can be used as a marker for drug-induced ER stress.

  1. Aberrant Neuronal Differentiation and Inhibition of Dendrite Outgrowth Resulting from Endoplasmic Reticulum Stress

    PubMed Central

    Kawada, Koichi; Iekumo, Takaaki; Saito, Ryo; Kaneko, Masayuki; Mimori, Seisuke; Nomura, Yasuyuki; Okuma, Yasunobu

    2014-01-01

    Neural stem cells (NSCs) play an essential role in development of the central nervous system. Endoplasmic reticulum (ER) stress induces neuronal death. After neuronal death, neurogenesis is generally enhanced to repair the damaged regions. However, it is unclear whether ER stress directly affects neurogenesis-related processes such as neuronal differentiation and dendrite outgrowth. We evaluated whether neuronal differentiation and dendrite outgrowth were regulated by HRD1, a ubiquitin ligase that was induced under mild conditions of tunicamycin-induced ER stress. Neurons were differentiated from mouse embryonic carcinoma P19 cells by using retinoic acid. The differentiated cells were cultured for 8 days with or without tunicamycin and HRD1 knockdown. The ER stressor led to markedly increased levels of ER stress. ER stress increased the expression levels of neuronal marker βIII-tubulin in 8-day-differentiated cells. However, the neurites of dendrite marker microtubule-associated protein-2 (MAP-2)-positive cells appeared to retract in response to ER stress. Moreover, ER stress markedly reduced the dendrite length and MAP-2 expression levels, whereas it did not affect the number of surviving mature neurons. In contrast, HRD1 knockdown abolished the changes in expression of proteins such as βIII-tubulin and MAP-2. These results suggested that ER stress caused aberrant neuronal differentiation from NSCs followed by the inhibition of neurite outgrowth. These events may be mediated by increased HRD1 expression. PMID:24723324

  2. Naphthoquinone derivative PPE8 induces endoplasmic reticulum stress in p53 null H1299 cells.

    PubMed

    Lien, Jin-Cherng; Huang, Chien-Chun; Lu, Te-Jung; Tseng, Chih-Hsiang; Sung, Ping-Jyun; Lee, Hong-Zin; Bao, Bo-Ying; Kuo, Yueh-Hsiung; Lu, Te-Ling

    2015-01-01

    Endoplasmic reticulum (ER) plays a key role in synthesizing secretory proteins and sensing signal function in eukaryotic cells. Responding to calcium disturbance, oxidation state change, or pharmacological agents, ER transmembrane protein, inositol-regulating enzyme 1 (IRE1), senses the stress and triggers downstream signals. Glucose-regulated protein 78 (GRP78) dissociates from IRE1 to assist protein folding and guard against cell death. In prolonged ER stress, IRE1 recruits and activates apoptosis signal-regulating kinase 1 (ASK1) as well as downstream JNK for cell death. Naphthoquinones are widespread natural phenolic compounds. Vitamin K3, a derivative of naphthoquinone, inhibits variant tumor cell growth via oxygen uptake and oxygen stress. We synthesized a novel naphthoquinone derivative PPE8 and evaluated capacity to induce ER stress in p53 null H1299 and p53 wild-type A549 cells. In H1299 cells, PPE8 induced ER enlargement, GRP78 expression, and transient IER1 activation. Activated IRE1 recruited ASK1 for downstream JNK phosphorylation. IRE1 knockdown by siRNA attenuated PPE8-induced JNK phosphorylation and cytotoxicity. Prolonged JNK phosphorylation may be involved in PPE8-induced cytotoxicity. Such results did not arise in A549 cells, but p53 knockdown by siRNA restored PPE8-induced GRP78 expression and JNK phosphorylation. We offer a novel compound to induce ER stress and cytotoxicity in p53-deficient cancer cells, presenting an opportunity for treatment.

  3. Toll-like receptor 4-induced endoplasmic reticulum stress contributes to endothelial dysfunction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Impairment of vasodilator action of insulin is associated with endothelial dysfunction and insulin resistance. Endoplasmic reticulum (ER) stress is implicated as one of the mechanisms for pathophysiology of various cardiometabolic syndromes, including insulin resistance and endothelial dysfunction. ...

  4. Moderate endoplasmic reticulum stress activates a PERK and p38-dependent apoptosis.

    PubMed

    Lumley, Emily C; Osborn, Acadia R; Scott, Jessica E; Scholl, Amanda G; Mercado, Vicki; McMahan, Young T; Coffman, Zachary G; Brewster, Jay L

    2017-01-01

    The endoplasmic reticulum (ER) has the ability to signal organelle dysfunction via a complex signaling network known as the unfolded protein response (UPR). In this work, hamster fibroblast cells exhibiting moderate levels of ER stress were compared to those exhibiting severe ER stress. Inhibition of N-linked glycosylation was accomplished via a temperature-sensitive mutation in the Dad1 subunit of the oligosaccharyltransferase (OST) complex or by direct inhibition with tunicamycin (Tm). Temperature shift (TS) treatment generated weak activation of ER stress signaling when compared to doses of Tm that are typically used in ER stress studies (500-1000 nM). A dose-response analysis of key ER stress signaling mediators, inositol-requiring enzyme 1 (IRE1) and protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK), revealed 20-40 nM of Tm to generate activation intensity similar to TS treatment. In parental BHK21 cells, moderate (20-40 nM) and high doses (200-1000 nM) of Tm were compared to identify physiological and signaling-based differences in stress response. Inhibition of ER Ca(2+) release via ITPR activity with 2-aminoethoxydiphenyl borate (2-APB) or Xestospongin C (XeC) was sufficient to protect against apoptosis induced by moderate but not higher doses of Tm. Analysis of kinase activation over a range of Tm exposures revealed the p38 stress-activated protein kinase (SAPK) to display increasing activation with Tm dosage. Interestingly, Tm induced the extracellular regulated kinases (Erk1/2) only at moderate doses of Tm. Inhibition of ER transmembrane stress sensors (IRE1, PERK) or cytosolic signaling mediators (p38, Jnk1, Erk1/2) was used to evaluate pathways involved in apoptosis activation during ER stress. Inhibition of either PERK or p38 was sufficient to reduce cell death and apoptosis induced by moderate, but not high, doses of Tm. During ER stress, cells exhibited a rapid decline in anti-apoptotic Mcl-1 and survivin proteins. Inhibition of

  5. Novel targets for endoplasmic reticulum stress-induced apoptosis in B-CLL.

    PubMed

    Rosati, Emanuela; Sabatini, Rita; Rampino, Giuliana; De Falco, Filomena; Di Ianni, Mauro; Falzetti, Franca; Fettucciari, Katia; Bartoli, Andrea; Screpanti, Isabella; Marconi, Pierfrancesco

    2010-10-14

    A better understanding of apoptotic signaling in B-chronic lymphocytic leukemia (B-CLL) cells may help to define new therapeutic strategies. This study investigated endoplasmic reticulum (ER) stress signaling in spontaneous apoptosis of B-CLL cells and whether manipulating ER stress increases their apoptosis. Results show that a novel ER stress-triggered caspase cascade, initiated by caspase-4 and involving caspase-8 and -3, plays an important role in spontaneous B-CLL cell apoptosis. ER stress-induced apoptosis in B-CLL cells also involves CHOP/GADD153 up-regulation, increased JNK1/2 phosphorylation, and caspase-8-mediated cleavage of Bap31 to Bap20, known to propagate apoptotic signals from ER to mitochondria. In ex vivo B-CLL cells, some apoptotic events associated with mitochondrial pathway also occur, including mitochondrial cytochrome c release and caspase-9 processing. However, pharmacologic inhibition studies show that caspase-9 plays a minor role in B-CLL cell apoptosis. ER stress also triggers survival signals in B-CLL cells by increasing BiP/GRP78 expression. Manipulating ER signaling by siRNA down-regulation of BiP/GRP78 or treating B-CLL cells with 2 well-known ER stress-inducers, tunicamycin and thapsigargin, increases their apoptosis. Overall, our findings show that ER triggers an essential pathway for B-CLL cell apoptosis and suggest that genetic and pharmacologic manipulation of ER signaling could represent an important therapeutic strategy.

  6. Endoplasmic Reticulum Stress and Homeostasis in Reproductive Physiology and Pathology.

    PubMed

    Guzel, Elif; Arlier, Sefa; Guzeloglu-Kayisli, Ozlem; Tabak, Mehmet Selcuk; Ekiz, Tugba; Semerci, Nihan; Larsen, Kellie; Schatz, Frederick; Lockwood, Charles Joseph; Kayisli, Umit Ali

    2017-04-08

    The endoplasmic reticulum (ER), comprises 60% of the total cell membrane and interacts directly or indirectly with several cell organelles i.e., Golgi bodies, mitochondria and proteasomes. The ER is usually associated with large numbers of attached ribosomes. During evolution, ER developed as the specific cellular site of synthesis, folding, modification and trafficking of secretory and cell-surface proteins. The ER is also the major intracellular calcium storage compartment that maintains cellular calcium homeostasis. During the production of functionally effective proteins, several ER-specific molecular steps sense quantity and quality of synthesized proteins as well as proper folding into their native structures. During this process, excess accumulation of unfolded/misfolded proteins in the ER lumen results in ER stress, the homeostatic coping mechanism that activates an ER-specific adaptation program, (the unfolded protein response; UPR) to increase ER-associated degradation of structurally and/or functionally defective proteins, thus sustaining ER homeostasis. Impaired ER homeostasis results in aberrant cellular responses, contributing to the pathogenesis of various diseases. Both female and male reproductive tissues undergo highly dynamic cellular, molecular and genetic changes such as oogenesis and spermatogenesis starting in prenatal life, mainly controlled by sex-steroids but also cytokines and growth factors throughout reproductive life. These reproductive changes require ER to provide extensive protein synthesis, folding, maturation and then their trafficking to appropriate cellular location as well as destroying unfolded/misfolded proteins via activating ER-associated degradation mediated proteasomes. Many studies have now shown roles for ER stress/UPR signaling cascades in the endometrial menstrual cycle, ovarian folliculogenesis and oocyte maturation, spermatogenesis, fertilization, pre-implantation embryo development and pregnancy and parturition

  7. Roles of endoplasmic reticulum stress-mediated apoptosis in M1-polarized macrophages during mycobacterial infections

    PubMed Central

    Lim, Yun-Ji; Yi, Min-Hee; Choi, Ji-Ae; Lee, Junghwan; Han, Ji-Ye; Jo, Sung-Hee; Oh, Sung-Man; Cho, Hyun Jin; Kim, Dong Woon; Kang, Min-Woong; Song, Chang-Hwa

    2016-01-01

    Alteration of macrophage function has an important regulatory impact on the survival of intracellular mycobacteria. We found that macrophages infected with attenuated Mycobacterium tuberculosis (Mtb) strain H37Ra had elevated expression of M1-related molecules, whereas the M2 phenotype was dominant in macrophages infected with virulent Mtb H37Rv. Further, the TLR signalling pathway played an important role in modulating macrophage polarization against Mtb infection. Interestingly, endoplasmic reticulum (ER) stress was significantly increased in M1 polarized macrophages and these macrophages effectively removed intracellular Mtb, indicating that ER stress may be an important component of the host immune response to Mtb in M1 macrophages. This improved understanding of the mechanisms that regulate macrophage polarization could provide new therapeutic strategies for tuberculosis. PMID:27845414

  8. Endoplasmic Reticulum Stress PERK-ATF4-CHOP Pathway Is Associated with Hypothalamic Neuronal Injury in Different Durations of Stress in Rats

    PubMed Central

    Yi, Shanyong; Shi, Weibo; Wang, He; Ma, Chunling; Zhang, Xiaojing; Wang, Songjun; Cong, Bin; Li, Yingmin

    2017-01-01

    The hypothalamus, which is the initial part of the hypothalamic-pituitary-adrenal (HPA) axis, plays a critical role in regulating stress in the central nervous system. The present study aimed to determine whether endoplasmic reticulum stress in hypothalamic neurons is differentially stimulated by varying durations of stress exposure, which ultimately leads to pathological changes in neurons by affecting HPA axis function. There is a need for better morphological evidence of the mechanisms involved in stress-induced neuron injury. A stress model was established in rats by restraining for 8 h and forced ice-water swimming for 5 min each day. The stress-inducing process lasted for 1, 3, 7, 14, and 21 days. Enzyme-linked immunosorbent assay (ELISA) was used to assay serum glucocorticoid levels. Thionine staining was used to observe morphological changes in hypothalamic neurons. Immunohistochemistry and microscopy-based multicolor tissue cytometry (MMTC) was used to detect changes in expression of endoplasmic reticulum stress protein GRP78, ATF4, and CHOP. Serum glucocorticoid levels significantly increased after 3 days of stress exposure and the levels peaked by 7 days. By 21 days, however, the levels were significantly decreased. Thionine staining revealed that prolonged stress exposure resulted in hypothalamic neurons with edema, a lack of Nissl bodies, and pyknotic neurons. Immunohistochemistry and MMTC showed that increasing stress periods significantly decreased GRP78 expression, although ATF4 and CHOP protein expression significantly increased. Stress resulted in pathological changes and significant dynamic changes because of endoplasmic reticulum stress in rat hypothalamic neurons. These results suggested that the endoplasmic reticulum stress PERK-ATF4-CHOP pathway may be associated with hypothalamic neuronal injury. PMID:28392758

  9. Ultraviolet a induces endoplasmic reticulum stress response in human dermal fibroblasts.

    PubMed

    Komori, Ryota; Taniguchi, Mai; Ichikawa, Yoshiaki; Uemura, Aya; Oku, Masaya; Wakabayashi, Sadao; Higuchi, Kazuhiko; Yoshida, Hiderou

    2012-01-01

    The endoplasmic reticulum (ER) stress response is a cytoprotective mechanism against the accumulation of unfolded proteins in the ER (ER stress) that consists of three response pathways (the ATF6, IRE1 and PERK pathways) in mammals. These pathways regulate the transcription of ER-related genes through specific cis-acting elements, ERSE, UPRE and AARE, respectively. Because the mammalian ER stress response is markedly activated in professional secretory cells, its main function was thought to be to upregulate the capacity of protein folding in the ER in accordance with the increased synthesis of secretory proteins. Here, we found that ultraviolet A (UVA) irradiation induced the conversion of an ER-localized sensor pATF6α(P) to an active transcription factor pATF6α(N) in normal human dermal fibroblasts (NHDFs). UVA also induced IRE1-mediated splicing of XBP1 mRNA as well as PERK-mediated phosphorylation of an α subunit of eukaryotic initiation factor 2. Consistent with these observations, we found that UVA increased transcription from ERSE, UPRE and AARE elements. From these results, we concluded that UVA irradiation activates all branches of the mammalian ER stress response in NHDFs. This suggests that the mammalian ER stress response is activated by not only intrinsic stress but also environmental stress.

  10. Visualization of endoplasmic reticulum stressed cells for forward genetic studies in plants.

    PubMed

    Hayashi, Shimpei; Takaiwa, Fumio

    2015-05-15

    In eukaryotes, various cellular events are attended by a risk of triggering stress in the endoplasmic reticulum (ER). Such risks are assumed to be minimized by sophisticated regulation systems, but the nature of these systems remains largely unknown in plants. Here, transgenic Arabidopsis plants, intended for use in forward genetic studies of plant ER stress, are described. AtBiP3 promoter activity clearly reflected the effects of inducers of ER stress, such as tunicamycin, dithiothreitol, and salicylic acid. Thus transgenic plants, containing the AtBiP3 promoter coupled to a fluorescent protein-encoding gene, were generated to enable visual detection of cells experiencing ER stress in living plants. Mutagenization of these transgenic plants produced seedlings which exhibited altered fluorescence patterns. Constitutive fluorescence was observed in a number of independent lines, suggesting the plant genome includes many genes whose mutation results in ER stress. Some mutants showed strong fluorescence with different tissue specificity, implying potential ER stresses in individual cellular events. These results indicate that forward genetic approaches will provide useful information in the understanding of ER stress.

  11. Endoplasmic reticulum stress suppresses lipin-1 expression in 3T3-L1 adipocytes

    SciTech Connect

    Takahashi, Nobuhiko; Hiranaka, Natsumi; Suzuki, Takeshi; Yui, Tomoo; Akanuma, Masayoshi; Kanazawa, Kaoru; Yoshida, Mika; Naito, Sumiyoshi; Fujiya, Mikihiro; Kohgo, Yutaka

    2013-02-01

    Highlights: ► Lipin-1 involves lipid metabolism, adipocyte differentiation, and inflammation. ► Adipose lipin-1 expression is reduced in obesity. ► ER stress suppresses lipin-1 expression in 3T3-L1 adipocytes. ► Activation of PPAR-γ recovers ER stress-induced lipin-1 reduction. -- Abstract: Lipin-1 plays crucial roles in the regulation of lipid metabolism and cell differentiation in adipocytes. In obesity, adipose lipin-1 mRNA expression is decreased and positively correlated with systemic insulin sensitivity. Amelioration of the lipin-1 depletion might be improved dysmetabolism. Although some cytokines such as TNF-α and interleukin-1β reduces adipose lipin-1 expression, the mechanism of decreased adipose lipin-1 expression in obesity remains unclear. Recently, endoplasmic reticulum (ER) stress is implicated in the pathogenesis of obesity. Here we investigated the role of ER stress on the lipin-1 expression in 3T3-L1 adipocytes. We demonstrated that lipin-1 expression was suppressed by the treatment with ER stress inducers (tunicamycin and thapsigargin) at transcriptional level. We also showed that constitutive lipin-1 expression could be maintained by peroxisome proliferator-activated receptor-γ in 3T3-L1 adipocytes. Activation of peroxisome proliferator-activated receptor-γ recovered the ER stress-induced lipin-1 suppression. These results suggested that ER stress might be involved in the pathogenesis of obesity through lipin-1 depletion.

  12. Relevance of Endoplasmic Reticulum Stress Cell Signaling in Liver Cold Ischemia Reperfusion Injury

    PubMed Central

    Folch-Puy, Emma; Panisello, Arnau; Oliva, Joan; Lopez, Alexandre; Castro Benítez, Carlos; Adam, René; Roselló-Catafau, Joan

    2016-01-01

    The endoplasmic reticulum (ER) is involved in calcium homeostasis, protein folding and lipid biosynthesis. Perturbations in its normal functions lead to a condition called endoplasmic reticulum stress (ERS). This can be triggered by many physiopathological conditions such as alcoholic steatohepatitis, insulin resistance or ischemia-reperfusion injury. The cell reacts to ERS by initiating a defensive process known as the unfolded protein response (UPR), which comprises cellular mechanisms for adaptation and the safeguarding of cell survival or, in cases of excessively severe stress, for the initiation of the cell death program. Recent experimental data suggest the involvement of ERS in ischemia/reperfusion injury (IRI) of the liver graft, which has been considered as one of major problems influencing outcome after liver transplantation. The purpose of this review is to summarize updated data on the molecular mechanisms of ERS/UPR and the consequences of this pathology, focusing specifically on solid organ preservation and liver transplantation models. We will also discuss the potential role of ERS, beyond the simple adaptive response and the regulation of cell death, in the modification of cell functional properties and phenotypic changes. PMID:27231901

  13. Endoplasmic Reticulum Stress Controls M2 Macrophage Differentiation and Foam Cell Formation*

    PubMed Central

    Oh, Jisu; Riek, Amy E.; Weng, Sherry; Petty, Marvin; Kim, David; Colonna, Marco; Cella, Marina; Bernal-Mizrachi, Carlos

    2012-01-01

    Macrophages are essential in atherosclerosis progression, but regulation of the M1 versus M2 phenotype and their role in cholesterol deposition are unclear. We demonstrate that endoplasmic reticulum (ER) stress is a key regulator of macrophage differentiation and cholesterol deposition. Macrophages from diabetic patients were classically or alternatively stimulated and then exposed to oxidized LDL. Alternative stimulation into M2 macrophages lead to increased foam cell formation by inducing scavenger receptor CD36 and SR-A1 expression. ER stress induced by alternative stimulation was necessary to generate the M2 phenotype through JNK activation and increased PPARγ expression. The absence of CD36 or SR-A1 signaling independently of modified cholesterol uptake decreased ER stress and prevented the M2 differentiation typically induced by alternative stimulation. Moreover, suppression of ER stress shifted differentiated M2 macrophages toward an M1 phenotype and subsequently suppressed foam cell formation by increasing HDL- and apoA-1-induced cholesterol efflux indicating suppression of macrophage ER stress as a potential therapy for atherosclerosis. PMID:22356914

  14. Endoplasmic reticulum stress induces PRNP prion protein gene expression in breast cancer

    PubMed Central

    2013-01-01

    Introduction High prion protein (PrP) levels are associated with breast, colon and gastric cancer resistance to treatment and with a poor prognosis for the patients. However, little is known about the underlying molecular mechanism(s) regulating human PrP gene (PRNP) expression in cancers. Because endoplasmic reticulum (ER) stress is associated with solid tumors, we investigated a possible regulation of PRNP gene expression by ER stress. Methods Published microarray databases of breast cancer tissues and breast carcinoma cell lines were analyzed for PrP mRNA and ER stress marker immunoglobulin heavy chain binding protein (BiP) levels. Breast cancer tissue microarrays (TMA) were immunostained for BiP and PrP. Breast carcinoma MCF-7, MDA-MB-231, HS578T and HCC1500 cells were treated with three different ER stressors - Brefeldin A, Tunicamycin, Thapsigargin - and levels of PrP mRNA or protein assessed by RT-PCR and Western blot analyses. A human PRNP promoter-luciferase reporter was used to assess transcriptional activation by ER stressors. Site-directed mutagenesis identified the ER stress response elements (ERSE). Chromatin immunoprecipitation (ChIP) analyses were done to identify the ER stress-mediated transcriptional regulators. The role of cleaved activating transcription factor 6α (ΔATF6α) and spliced X-box protein-1 (sXBP1) in PRNP gene expression was assessed with over-expression or silencing techniques. The role of PrP protection against ER stress was assessed with PrP siRNA and by using Prnp null cell lines. Results We find that mRNA levels of BiP correlated with PrP transcript levels in breast cancer tissues and breast carcinoma cell lines. PrP mRNA levels were enriched in the basal subtype and were associated with poor prognosis in breast cancer patients. Higher PrP and BiP levels correlated with increasing tumor grade in TMA. ER stress was a positive regulator of PRNP gene transcription in MCF-7 cells and luciferase reporter assays identified one ER

  15. Endoplasmic reticulum stress signal impairs erythropoietin production: a role for ATF4.

    PubMed

    Chiang, Chih-Kang; Nangaku, Masaomi; Tanaka, Tetsuhiro; Iwawaki, Takao; Inagi, Reiko

    2013-02-15

    Hypoxia upregulates the hypoxia-inducible factor (HIF) pathway and the endoplasmic reticulum (ER) stress signal, unfolded protein response (UPR). The cross talk of both signals affects the pathogenic alteration by hypoxia. Here we showed that ER stress induced by tunicamycin or thapsigargin suppressed inducible (CoCl(2) or hypoxia) transcription of erythropoietin (EPO), a representative HIF target gene, in HepG2. This suppression was inversely correlated with UPR activation, as estimated by expression of the UPR regulator glucose-regulated protein 78, and restored by an ER stress inhibitor, salubrinal, in association with normalization of the UPR state. Importantly, the decreased EPO expression was also observed in HepG2 overexpressing UPR activating transcription factor (ATF)4. Overexpression of mutated ATF4 that lacks the transcriptional activity did not alter EPO transcriptional regulation. Transcriptional activity of the EPO 3'-enhancer, which is mainly regulated by HIF, was abolished by both ER stressors and ATF4 overexpression, while nuclear HIF accumulation or expression of other HIF target genes was not suppressed by ER stress. Chromatin immunoprecipitation analysis identified a novel ATF4 binding site (TGACCTCT) within the EPO 3'-enhancer region, suggesting a distinct role for ATF4 in UPR-dependent suppression of the enhancer. Induction of ER stress in rat liver and kidney by tunicamycin decreased the hepatic and renal mRNA and plasma level of EPO. Collectively, ER stress selectively impairs the transcriptional activity of EPO but not of other HIF target genes. This effect is mediated by suppression of EPO 3'-enhancer activity via ATF4 without any direct effect on HIF, indicating that UPR contributes to oxygen-sensing regulation of EPO.

  16. Regulation of endoplasmic reticulum turnover by selective autophagy.

    PubMed

    Khaminets, Aliaksandr; Heinrich, Theresa; Mari, Muriel; Grumati, Paolo; Huebner, Antje K; Akutsu, Masato; Liebmann, Lutz; Stolz, Alexandra; Nietzsche, Sandor; Koch, Nicole; Mauthe, Mario; Katona, Istvan; Qualmann, Britta; Weis, Joachim; Reggiori, Fulvio; Kurth, Ingo; Hübner, Christian A; Dikic, Ivan

    2015-06-18

    The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication. Constant ER turnover and modulation is needed to meet different cellular requirements and autophagy has an important role in this process. However, its underlying regulatory mechanisms remain unexplained. Here we show that members of the FAM134 reticulon protein family are ER-resident receptors that bind to autophagy modifiers LC3 and GABARAP, and facilitate ER degradation by autophagy ('ER-phagy'). Downregulation of FAM134B protein in human cells causes an expansion of the ER, while FAM134B overexpression results in ER fragmentation and lysosomal degradation. Mutant FAM134B proteins that cause sensory neuropathy in humans are unable to act as ER-phagy receptors. Consistently, disruption of Fam134b in mice causes expansion of the ER, inhibits ER turnover, sensitizes cells to stress-induced apoptotic cell death and leads to degeneration of sensory neurons. Therefore, selective ER-phagy via FAM134 proteins is indispensable for mammalian cell homeostasis and controls ER morphology and turnover in mice and humans.

  17. Endoplasmic Reticulum Stress and the Unfolded Protein Responses in Retinal Degeneration

    PubMed Central

    Zhang, Sarah X.; Sanders, Emily; Fliesler, Steven J.; Wang, Joshua J.

    2014-01-01

    The endoplasmic reticulum (ER) is the primary intracellular organelle responsible for protein and lipid biosynthesis, protein folding and trafficking, calcium homeostasis, and several other vital processes in cell physiology. Disturbance in ER function results in ER stress and subsequent activation of the unfolded protein response (UPR). The UPR up-regulates ER chaperones, reduces protein translation, and promotes clearance of cytotoxic misfolded proteins to restore ER homeostasis. If this vital process fails, the cell will be signaled to enter apoptosis, resulting in cell death. Sustained ER stress also can trigger an inflammatory response and exacerbate oxidative stress, both of which contribute synergistically to tissue damage. Studies performed over the past decade have implicated ER stress in a broad range of human diseases, including neurodegenerative diseases, cancer, diabetes, and vascular disorders. Several of these diseases also entail retinal dysfunction and degeneration caused by injury to retinal neurons and/or to the blood vessels that supply retinal cells with nutrients, trophic and homeostatic factors, oxygen, and other essential molecules, as well as serving as a conduit for removal of waste products and potentially toxic substances from the retina. Collectively, such injuries represent the leading cause of blindness world-wide in all age groups. Herein, we summarize recent progress on the study of ER stress and UPR signaling in retinal biology and discuss the molecular mechanisms and the potential clinical applications of targeting ER stress as a new therapeutic approach to prevent and treat neuronal degeneration in the retina. PMID:24792589

  18. Obesity-induced endoplasmic reticulum stress suppresses nuclear factor-Y expression.

    PubMed

    Liu, Yulan; Zhang, Yuwei; Zhang, Yanjie; Zhang, Jinlong; Liu, Yin; Feng, Peiqun; Su, Zhiguang

    2017-02-01

    Nuclear transcription factor Y (NF-Y) is an evolutionarily conserved transcription factor composed of three subunits, NF-YA, NF-YB, and NF-YC. NF-Y plays crucial roles in pre-adipocyte maintenance and/or commitment to adipogenesis. NF-YA dysfunction in adipocyte resulted in an age-dependent progressive loss of adipose tissue associated with metabolic complications. Endoplasmic reticulum (ER) stress has emerged as an important mediator in the pathogenesis of obesity. However, it is not known if NF-YA is involved in the ER stress-mediated pathogenesis of obesity. We first examined the effects of ER stress on the NF-YA expression in cultured 3T3-L1 adipocytes; then in ob/ob genetic obesity mice, we tested the effect of chemical chaperones alleviating ER stress on the expression levels of NF-YA. Subsequently, we inhibited the new mRNA synthesis using actinomycin D in 3T3-L1 cells to explore the mechanism modulating NF-YA expression. Finally, we evaluated the involvement of PPARg in the regulation of NF-YA expression by ER stress. We demonstrated that both obesity- and chemical chaperone -induced ER stress suppressed NF-YA expression and alleviation of ER stress by chemical chaperone could recover NF-YA expression in ob/ob mice. Moreover, we showed that ER stress suppressed NF-YA mRNA transcription through the involvement of peroxisome proliferator-activated receptor gamma (PPARg). Activation of PPARg ameliorates the ER stress-induced NF-YA suppression. Our findings may point to a possible role of NF-YA in stress conditions that occur in chronic obesity, ER stress might be involved in the pathogenesis of obesity through NF-YA depletion.

  19. Physiological functions of endoplasmic reticulum stress transducer OASIS in central nervous system.

    PubMed

    Saito, Atsushi

    2014-01-01

    Eukaryotic cells can adapt to endoplasmic reticulum (ER) dysfunction by producing diverse signals from the ER to the cytosol or nucleus. These signaling pathways are collectively known as the unfolded protein response (UPR). The canonical branches of the UPR are mediated by three ER membrane-bound proteins: double-stranded RNA-dependent protein kinase (PKR)-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme-1 (IRE1) and activating transcription factor 6 (ATF6). These ER stress transducers basically play important roles in cell survival after ER stress. Recently, novel types of ER stress transducers that share a region of high sequence similarity with ATF6 have been identified. They have a transmembrane domain, which allows them to associate with the ER, and possess a transcription-activation domain and a basic leucine zipper (bZIP) domain. These membrane-bound bZIP transcription factors include OASIS, BBF2H7 CREBH, CREB4 and Luman, and are collectively referred to as OASIS family members. Despite their structural similarities with ATF6, differences in activating stimuli and tissue distribution indicate specialized functions of each member on regulating UPR signaling in specific organs and tissues. One of them, OASIS, is expressed preferentially in astrocytes in the central nervous system (CNS). OASIS temporally regulates the differentiation from neural precursor cells into astrocytes to promote the expression of Glial Cell Missing 1 through dynamic interactions among OASIS family members followed by accelerating demethylation of the Gfap promoter. This review is a summary of our current understanding of the physiological functions of OASIS in the CNS.

  20. Diet-induced obesity induces endoplasmic reticulum stress and insulin resistance in the amygdala of rats☆

    PubMed Central

    Castro, Gisele; C. Areias, Maria Fernanda; Weissmann, Lais; Quaresma, Paula G.F.; Katashima, Carlos K.; Saad, Mario J.A.; Prada, Patricia O.

    2013-01-01

    Insulin acts in the hypothalamus, decreasing food intake (FI) by the IR/PI3K/Akt pathway. This pathway is impaired in obese animals and endoplasmic reticulum (ER) stress and low-grade inflammation are possible mechanisms involved in this impairment. Here, we highlighted the amygdala as an important brain region for FI regulation in response to insulin. This regulation was dependent on PI3K/AKT pathway similar to the hypothalamus. Insulin was able to decrease neuropeptide Y (NPY) and increase oxytocin mRNA levels in the amygdala via PI3K, which may contribute to hypophagia. Additionally, obese rats did not reduce FI in response to insulin and AKT phosphorylation was decreased in the amygdala, suggesting insulin resistance. Insulin resistance was associated with ER stress and low-grade inflammation in this brain region. The inhibition of ER stress with PBA reverses insulin action/signaling, decreases NPY and increases oxytocin mRNA levels in the amygdala from obese rats, suggesting that ER stress is probably one of the mechanisms that induce insulin resistance in the amygdala. PMID:24251109

  1. Endoplasmic Reticulum Stress in Heat- and Shake-Induced Injury in the Rat Small Intestine

    PubMed Central

    Yin, Peng; Xu, Jianqin; He, Shasha; Liu, Fenghua; Yin, Jie; Wan, Changrong; mei, Chen; Yin, Yulong; Xu, Xiaolong; Xia, Zhaofei

    2015-01-01

    We investigated the mechanisms underlying damage to rat small intestine in heat- and shake-induced stress. Eighteen Sprague-Dawley rats were randomly divided into a control group and a 3-day stressed group treated 2 h daily for 3 days on a rotary platform at 35°C and 60 r/min. Hematoxylin and eosin-stained paraffin sections of the jejunum following stress revealed shedding of the villus tip epithelial cells and lamina propria exposure. Apoptosis increased at the villus tip and extended to the basement membrane. Photomicrographs revealed that the microvilli were shorter and sparser; the nuclear envelope invaginated and gaps in the karyolemma increased; and the endoplasmic reticulum (ER) swelled significantly. Gene microarray analysis assessed 93 differentially expressed genes associated with apoptosis, ER stress, and autophagy. Relevant genes were compiled from the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Forty-one genes were involved in the regulation of apoptosis, fifteen were related to autophagy, and eleven responded to ER stress. According to KEGG, the apoptosis pathways, mitogen-activated protein kinase(MAPK) signaling pathway, the mammalian target of rapamycin (mTOR) signaling pathway, and regulation of autophagy were involved. Caspase3 (Casp3), caspase12 (Casp12), and microtubule-associate proteins 1 light chain 3(LC3) increased significantly at the villus tip while mTOR decreased; phosphorylated-AKT (P-AKT) decreased. ER stress was involved and induced autophagy and apoptosis in rat intestinal damage following heat and shake stress. Bioinformatic analysis will help determine the underlying mechanisms in stress-induced damage in the small intestine. PMID:26636675

  2. The adaptive endoplasmic reticulum stress response to lipotoxicity in progressive human nonalcoholic fatty liver disease.

    PubMed

    Lake, April D; Novak, Petr; Hardwick, Rhiannon N; Flores-Keown, Brieanna; Zhao, Fei; Klimecki, Walter T; Cherrington, Nathan J

    2014-01-01

    Nonalcoholic fatty liver disease (NAFLD) may progress from simple steatosis to severe, nonalcoholic steatohepatitis (NASH) in 7%-14% of the U.S. population through a second "hit" in the form of increased oxidative stress and inflammation. Endoplasmic reticulum (ER) stress signaling and the unfolded protein response (UPR) are triggered when high levels of lipids and misfolded proteins alter ER homeostasis creating a lipotoxic environment within NAFLD livers. The objective of this study was to determine the coordinate regulation of ER stress-associated genes in the progressive stages of human NAFLD. Human liver samples categorized as normal, steatosis, NASH (Fatty), and NASH (Not Fatty) were analyzed by individual Affymetrix GeneChip Human 1.0 ST microarrays, immunoblots, and immunohistochemistry. A gene set enrichment analysis was performed on autophagy, apoptosis, lipogenesis, and ER stress/UPR gene categories. An enrichment of downregulated genes in the ER stress-associated lipogenesis and ER stress/UPR gene categories was observed in NASH. Conversely, an enrichment of upregulated ER stress-associated genes for autophagy and apoptosis gene categories was observed in NASH. Protein expression of the adaptive liver response protein STC2 and the transcription factor X-box binding protein 1 spliced (XBP-1s) were significantly elevated among NASH samples, whereas other downstream ER stress proteins including CHOP, ATF4, and phosphorylated JNK and eIF2α were not significantly changed in disease progression. Increased nuclear accumulation of total XBP-1 protein was observed in steatosis and NASH livers. The findings reveal the presence of a coordinated, adaptive transcriptional response to hepatic ER stress in human NAFLD.

  3. The endoplasmic reticulum stress response in aging and age-related diseases

    PubMed Central

    Brown, Marishka K.; Naidoo, Nirinjini

    2012-01-01

    The endoplasmic reticulum(ER) is a multifunctional organelle within which protein folding, lipid biosynthesis, and calcium storage occurs. Perturbations such as energy or nutrient depletion, disturbances in calcium or redox status that disrupt ER homeostasis lead to the misfolding of proteins, ER stress and up-regulation of several signaling pathways coordinately called the unfolded protein response (UPR). The UPR is characterized by the induction of chaperones, degradation of misfolded proteins and attenuation of protein translation. The UPR plays a fundamental role in the maintenance of cellular homeostasis and thus is central to normal physiology. However, sustained unresolved ER stress leads to apoptosis. Aging linked declines in expression and activity of key ER molecular chaperones and folding enzymes compromise proper protein folding and the adaptive response of the UPR. One mechanism to explain age associated declines in cellular functions and age-related diseases is a progressive failure of chaperoning systems. In many of these diseases, proteins or fragments of proteins convert from their normally soluble forms to insoluble fibrils or plaques that accumulate in a variety of organs including the liver, brain or spleen. This group of diseases, which typically occur late in life includes Alzheimer's, Parkinson's, type II diabetes and a host of less well known but often equally serious conditions such as fatal familial insomnia. The UPR is implicated in many of these neurodegenerative and familial protein folding diseases as well as several cancers and a host of inflammatory diseases including diabetes, atherosclerosis, inflammatory bowel disease and arthritis. This review will discuss age-related changes in the ER stress response and the role of the UPR in age-related diseases. PMID:22934019

  4. Autophagy decreases alveolar macrophage apoptosis by attenuating endoplasmic reticulum stress and oxidative stress

    PubMed Central

    Fan, Tao; Chen, Lei; Huang, Zhixin; Mao, Zhangfan; Wang, Wei; Zhang, Boyou; Xu, Yao; Pan, Shize; Hu, Hao; Geng, Qing

    2016-01-01

    To study the impact of autophagy on alveolar macrophage apoptosis and its mechanism in the early stages of hypoxia, we established a cell hypoxia-reoxygenation model and orthotopic left lung ischemia-reperfusion model. Rat alveolar macrophages stably expressing RFP-LC3 were treated with autophagy inhibitor (3-methyladenine, 3-MA) or autophagy promoter (rapamycin), followed by hypoxia-reoxygenation treatment 2 h, 4 h or 6 h later. Twenty Sprague-Dawley male rats were randomly divided into four different groups: no blocking of left lung hilum (model group), left lung hilum blocked for 1h with DMSO lavage (control group), left lung hilum blocked for 1 h with 100 ml/kg 3-MA (5 μmol/L) lavage (3-MA group), and left lung hilum blocked for 1 h with 100 ml/kg rapamycin (250 nmol/L) lavage (rapamycin group). Rapamycin decreased the unfolded protein response, which reduced endoplasmic reticulum stress-mediated apoptosis in the presence of oxygen deficiency. Rapamycin increased superoxide dismutase activities and decreased malondialdehyde levels, whereas 3-MA decreased superoxide dismutase activities and increased malondialdehyde levels. Thus, autophagy decreases alveolar macrophage apoptosis by attenuating endoplasmic reticulum stress and oxidative stress in the early stage of hypoxia in vitro and in vivo. This could represent a new approach to protecting against lung ischemia-reperfusion injury. PMID:27888631

  5. Cationic polystyrene nanospheres induce autophagic cell death through the induction of endoplasmic reticulum stress

    NASA Astrophysics Data System (ADS)

    Chiu, Hui-Wen; Xia, Tian; Lee, Yu-Hsuan; Chen, Chun-Wan; Tsai, Jui-Chen; Wang, Ying-Jan

    2014-12-01

    Nanoparticles (NPs) have been used to produce a wide range of products that have applications in imaging and drug delivery in medicine. Due to their chemical stability, well-controlled sizes and surface charges, polystyrene (PS) NPs have been developed as biosensors and drug delivery carriers. However, the possible adverse biological effects and underlying mechanisms are still unclear. Recently, autophagy has been implicated in the regulation of cell death. In this study, we evaluated a library of PS NPs with different surface charges. We found that NH2-labeled polystyrene (NH2-PS) nanospheres were highly toxic with enhanced uptake in macrophage (RAW 264.7) and lung epithelial (BEAS-2B) cells. Furthermore, NH2-PS could induce autophagic cell death. NH2-PS increased autophagic flux due to reactive oxygen species (ROS) generation and endoplasmic reticulum (ER) stress caused by misfolded protein aggregation. The inhibition of ER stress decreased cytotoxicity and autophagy in the NH2-PS-treated cells. In addition, the Akt/mTOR and AMPK signaling pathways were involved in the regulation of NH2-PS-triggered autophagic cell death. These results suggest an important role of autophagy in cationic NP-induced cell death and provide mechanistic insights into the inhibition of the toxicity and safe material design.Nanoparticles (NPs) have been used to produce a wide range of products that have applications in imaging and drug delivery in medicine. Due to their chemical stability, well-controlled sizes and surface charges, polystyrene (PS) NPs have been developed as biosensors and drug delivery carriers. However, the possible adverse biological effects and underlying mechanisms are still unclear. Recently, autophagy has been implicated in the regulation of cell death. In this study, we evaluated a library of PS NPs with different surface charges. We found that NH2-labeled polystyrene (NH2-PS) nanospheres were highly toxic with enhanced uptake in macrophage (RAW 264.7) and lung

  6. A novel transmembrane protein defines the endoplasmic reticulum stress-induced cell death pathway.

    PubMed

    Tamaki, Tomoya; Kamatsuka, Kenta; Sato, Taku; Morooka, Shuntaro; Otsuka, Kosuke; Hattori, Masahiro; Sugiyama, Tomoyasu

    2017-03-08

    Mitochondrial membrane potential (ΔΨm) maintenance is physiologically critical in cells; its loss causes apoptotic signalling and cell death. Accumulating DNA mutations and unfolded proteins in stressed cells activate signalling pathways for cell death induction. Cancer cells often fail to die even in the presence of some death signalling proteins. Here, we report a short hairpin RNA (shRNA) with an artificial sequence, denoted Psi1 shRNA, which leads to ΔΨm loss in HCT116 cells. The Psi1 shRNA target gene was shown to encode transmembrane protein 117 (TMEM117). TMEM117 knockdown led to ΔΨm loss, increased reactive oxygen species levels, up-regulation of an endoplasmic reticulum (ER) stress sensor C/EBP homologous protein and active caspase-3 expression, and cell growth impairment, altering homeostasis towards cell death. TMEM117 levels were down-regulated in response to the ER stressor thapsigargin and decreased when cells showed ΔΨm loss. These results suggested that TMEM117 RNAi allowed apoptotic cell death. Therefore, TMEM117 probably mediates the signalling of ΔΨm loss in ER stress-mediated mitochondria-mediated cell death.

  7. Erlotinib promotes endoplasmic reticulum stress-mediated injury in the intestinal epithelium

    SciTech Connect

    Fan, Lu; Hu, Lingna; Yang, Baofang; Fang, Xianying; Gao, Zhe; Li, Wanshuai; Sun, Yang; Shen, Yan; Wu, Xuefeng; Shu, Yongqian; Gu, Yanhong; Wu, Xudong; Xu, Qiang

    2014-07-01

    Erlotinib, a popular drug for treating non-small cell lung cancer (NSCLC), causes diarrhea in approximately 55% of patients receiving this drug. In the present study, we found that erlotinib induced barrier dysfunction in rat small intestine epithelial cells (IEC-6) by increasing epithelial permeability and down-regulating E-cadherin. The mRNA levels of various pro-inflammatory cytokines (Il-6, Il-25 and Il-17f) were increased after erlotinib treatment in IEC-6 cells. Erlotinib concentration- and time-dependently induced apoptosis and endoplasmic reticulum (ER) stress in both IEC-6 and human colon epithelial cells (CCD 841 CoN). Intestinal epithelial injury was also observed in male C57BL/6J mice administrated with erlotinib. Knockdown of C/EBP homologous protein (CHOP) with small interference RNA partially reversed erlotinib-induced apoptosis, production of IL-6 and down-regulation of E-cadherin in cultured intestinal epithelial cells. In conclusion, erlotinib caused ER stress-mediated injury in the intestinal epithelium, contributing to its side effects of diarrhea in patients. - Highlights: • Erlotinib destroyed barrier integrity both in vitro and in vivo. • Erlotinib induced inflammation both in vitro and in vivo. • Erlotinib induced apoptosis both in vitro and in vivo. • ER stress contributed to erlotinib-induced barrier dysfunction.

  8. Fluoride-elicited developmental testicular toxicity in rats: Roles of endoplasmic reticulum stress and inflammatory response

    SciTech Connect

    Zhang, Shun; Jiang, Chunyang; Liu, Hongliang; Guan, Zhizhong; Zeng, Qiang; Zhang, Cheng; Lei, Rongrong; Xia, Tao; Gao, Hui; Yang, Lu; Chen, Yihu; Wu, Xue; Zhang, Xiaofei; Cui, Yushan; Yu, Linyu; Wang, Zhenglun; Wang, Aiguo

    2013-09-01

    Long-term excessive fluoride intake is known to be toxic and can damage a variety of organs and tissues in the human body. However, the molecular mechanisms underlying fluoride-induced male reproductive toxicity are not well understood. In this study, we used a rat model to simulate the situations of human exposure and aimed to evaluate the roles of endoplasmic reticulum (ER) stress and inflammatory response in fluoride-induced testicular injury. Sprague–Dawley rats were administered with sodium fluoride (NaF) at 25, 50 and 100 mg/L via drinking water from pre-pregnancy to gestation, birth and finally to post-puberty. And then the testes of male offspring were studied at 8 weeks of age. Our results demonstrated that fluoride treatment increased MDA accumulation, decreased SOD activity, and enhanced germ cell apoptosis. In addition, fluoride elevated mRNA and protein levels of glucose-regulated protein 78 (GRP78), inositol requiring ER-to-nucleus signal kinase 1 (IRE1), and C/EBP homologous protein (CHOP), indicating activation of ER stress signaling. Furthermore, fluoride also induced testicular inflammation, as manifested by gene up-regulation of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in a nuclear factor-κB (NF-κB)-dependent manner. These were associated with marked histopathological lesions including injury of spermatogonia, decrease of spermatocytes and absence of elongated spermatids, as well as severe ultrastructural abnormalities in testes. Taken together, our results provide compelling evidence that ER stress and inflammation would be novel and significant mechanisms responsible for fluoride-induced disturbance of spermatogenesis and germ cell loss in addition to oxidative stress. - Highlights: • We used a rat model to simulate the situations of human fluoride (F) exposure. • Developmental F exposure induces testicular damage related with oxidative stress.

  9. Sodium fluoride (NaF) induces the splenic apoptosis via endoplasmic reticulum (ER) stress pathway in vivo and in vitro

    PubMed Central

    Cui, Hengmin; Chen, Lian; Luo, Qin; Fang, Jing; Zuo, Zhicai; Deng, Junliang; Wang, Xun; Zhao, Ling

    2016-01-01

    At present, there are no reports on the relationship between fluoride-induced apoptosis and endoplasmic reticulum (ER) stress (ER stress) in the spleen of human and animals in vivo and in vitro. Therefore, the aim of this study was to define sodium fluoride (NaF)-induced apoptosis mediated by ER stress in the spleen of mice in vivo and in vitro. Apoptosis and expression levels of the ER stress-related proteins were detected by flow cytometry and western blot, respectively. The results showed that NaF treatment increased lymphocytes apoptosis, which was consistent with NaF-caused ER Stress. NaF-caused ER stress was characterized by up-regulating protein expression levels of glucose-regulated protein 78 (BiP) and glucose-regulated protein 94 (GRP94), and by activating unfolded protein response (UPR). The signaling pathway of ER stress-associated apoptosis was activated by up-regulating protein expression levels of cleaved cysteine aspartate specific protease-12 (cleaved caspase-12), growth arrest and DNA damage-inducible gene 153 (Gadd153/CHOP) and phosphorylation of JUN N-terminal kinase (p-JNK). Additionally, our in vitro study found that apoptotic rate was decreased with remarkable down-regulation of the cleaved caspase-12, CHOP, p-JNK after ER stress was inhibited by 4-Phenylbutyric acid (4-PBA) treatment. In conclusion, NaF-induced apoptosis may mediated by ER stress in the spleen. PMID:28039491

  10. A novel cellular stress response characterised by a rapid reorganisation of membranes of the endoplasmic reticulum

    PubMed Central

    Varadarajan, S; Bampton, E T W; Smalley, J L; Tanaka, K; Caves, R E; Butterworth, M; Wei, J; Pellecchia, M; Mitcheson, J; Gant, T W; Dinsdale, D; Cohen, G M

    2012-01-01

    Canonical endoplasmic reticulum (ER) stress, which occurs in many physiological and disease processes, results in activation of the unfolded protein response (UPR). We now describe a new, evolutionarily conserved cellular stress response characterised by a striking, but reversible, reorganisation of ER membranes that occurs independently of the UPR, resulting in impaired ER transport and function. This reorganisation is characterised by a dramatic redistribution and clustering of ER membrane proteins. ER membrane aggregation is regulated, in part, by anti-apoptotic BCL-2 family members, particularly MCL-1. Using connectivity mapping, we report the widespread occurrence of this stress response by identifying several structurally diverse chemicals from different pharmacological classes, including antihistamines, antimalarials and antipsychotics, which induce ER membrane reorganisation. Furthermore, we demonstrate the potential of ER membrane aggregation to result in pathological consequences, such as the long-QT syndrome, a cardiac arrhythmic abnormality, arising because of a novel trafficking defect of the human ether-a-go-go-related channel protein from the ER to the plasma membrane. Thus, ER membrane reorganisation is a feature of a new cellular stress pathway, clearly distinct from the UPR, with important consequences affecting the normal functioning of the ER. PMID:22955944

  11. Endoplasmic reticulum stress protects human thyroid carcinoma cell lines against ionizing radiation-induced apoptosis.

    PubMed

    Wu, Xin-Yu; Fan, Rui-Tai; Yan, Xin-Hui; Cui, Jing; Xu, Jun-Ling; Gu, Hao; Gao, Yong-Ju

    2015-03-01

    Radiotherapy is one of the most effective forms of cancer treatment, used in the treatment of a number of malignant tumors. However, the resistance of tumor cells to ionizing radiation remains a major therapeutic problem and the critical mechanisms determining radiation resistance are poorly defined. In the present study, a cellular endoplasmic reticulum (ER) stress microenvironment was established through the pretreatment of cultured thyroid cancer cells with tunicamycin (TM) and thapsigargin (TG), in order to mimic the ER stress response in a tumor microenvironment. This microenviroment was confirmed through the X‑box binding protein 1 splice process, glucose‑regulated protein 78 kD and ER degradation‑enhancing α‑mannosidase‑like mRNA expression. A clonogenic assay was used to measure cancer cell resistance to 60Co‑γ following TM pretreatment; in addition, human C/EBP homologous protein (CHOP) mRNA expression was determined and apoptosis assays were performed. The results showed that TM or TG pretreatment inhibited CHOP expression and reduced the apoptotic rate of cells. Furthermore, the results demonstrated that the induced ER stress response rendered cancer cells more resistant to ionizing radiation‑induced apoptosis. Therefore, the ER stress pathway may be a potential therapeutic target in order to improve the clinical efficiency of radiotherapy.

  12. Black tea protects against hypertension-associated endothelial dysfunction through alleviation of endoplasmic reticulum stress

    PubMed Central

    San Cheang, Wai; Yuen Ngai, Ching; Yen Tam, Ye; Yu Tian, Xiao; Tak Wong, Wing; Zhang, Yang; Wai Lau, Chi; Chen, Zhen Yu; Bian, Zhao-Xiang; Huang, Yu; Ping Leung, Fung

    2015-01-01

    Hypertensive patients have been found to be associated with elevated levels of homocysteine, known as hyperhomocysteinemia. Homocysteine (Hcy) can induce endoplasmic reticulum (ER) stress in endothelial cells. This study aims to investigate whether black tea (BT) protects against hypertension-associated endothelial dysfunction through alleviation of ER stress. Rat aortae and cultured rat aortic endothelial cells were treated with Hcy, BT extract, and theaflavin-3,3’-digallate (TF3). Male Sprague Dawley rats were infused with angiotensin II (Ang II) to induce hypertension and orally administrated with BT extract at 15 mg/kg/day for 2 weeks. Hcy impaired endothelium-dependent relaxations of rat aortae and led to ER stress in endothelial cells, which were ameliorated by co-incubation of BT extract and TF3. The blood pressure of Ang II-infused rats and plasma Hcy level were normalized by BT consumption. Impaired endothelium-dependent relaxations in renal arteries, carotid arteries and aortae, and flow-mediated dilatations in third-order mesenteric resistance arteries were improved. Elevations of ER stress markers and ROS level, plus down-regulation of Hcy metabolic enzymes in aortae from Ang II-infused rats were prevented by BT treatment. Our data reveal the novel cardiovascular benefits of BT in ameliorating vascular dysfunctions, providing insight into developing BT into beneficial dietary supplements in hypertensive patients. PMID:25976123

  13. PPARδ Is Required for Exercise to Attenuate Endoplasmic Reticulum Stress and Endothelial Dysfunction in Diabetic Mice.

    PubMed

    Cheang, Wai San; Wong, Wing Tak; Zhao, Lei; Xu, Jian; Wang, Li; Lau, Chi Wai; Chen, Zhen Yu; Ma, Ronald Ching Wan; Xu, Aimin; Wang, Nanping; Tian, Xiao Yu; Huang, Yu

    2017-02-01

    Physical activity has profound benefits on health, especially on cardiometabolic wellness. Experiments in rodents with trained exercise have shown that exercise improves vascular function and reduces vascular inflammation by modulating the balance between nitric oxide (NO) and oxidative stress. However, the upstream regulator of exercise-induced vascular benefits is unclear. We aimed to investigate the involvement of peroxisome proliferator-activated receptor δ (PPARδ) in exercise-induced vascular functional improvement. We show that PPARδ is a crucial mediator for exercise to exert a beneficial effect on the vascular endothelium in diabetic mice. In db/db mice and high-fat diet-induced obese mice, 4 weeks of treadmill exercise restored endothelium-dependent vasodilation of aortas and flow-mediated vasodilation in mesenteric resistance arteries, whereas genetic ablation of Ppard abolished such improvements. Exercise induces AMPK activation and subsequent PPARδ activation, which help to reduce endoplasmic reticulum (ER) and oxidative stress, thus increasing NO bioavailability in endothelial cells and vascular tissues. Chemical chaperones 4-phenylbutyric acid and tauroursodeoxycholic acid decrease ER stress and protect against endothelial dysfunction in diabetic mice. The results demonstrate that PPARδ-mediated inhibition of ER stress contributes to the vascular benefits of exercise and provides potentially effective targets for treating diabetic vasculopathy.

  14. Endoplasmic Reticulum Stress Cooperates in Zearalenone-Induced Cell Death of RAW 264.7 Macrophages.

    PubMed

    Chen, Fenglei; Li, Qian; Zhang, Zhe; Lin, Pengfei; Lei, Lanjie; Wang, Aihua; Jin, Yaping

    2015-08-20

    Zearalenone (ZEA) is a fungal mycotoxin that causes cell apoptosis and necrosis. However, little is known about the molecular mechanisms of ZEA toxicity. The objective of this study was to explore the effects of ZEA on the proliferation and apoptosis of RAW 264.7 macrophages and to uncover the signaling pathway underlying the cytotoxicity of ZEA in RAW 264.7 macrophages. This study demonstrates that the endoplasmic reticulum (ER) stress pathway cooperated in ZEA-induced cell death of the RAW 264.7 macrophages. Our results show that ZEA treatment reduced the viability of RAW 264.7 macrophages in a dose- and time-dependent manner as shown by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay (MTT) and flow cytometry assay. Western blots analysis revealed that ZEA increased the expression of glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP), two ER stress-related marker genes. Furthermore, treating the cells with the ER stress inhibitors 4-phenylbutyrate (4-PBA) or knocking down CHOP, using lentivirus encoded short hairpin interfering RNAs (shRNAs), significantly diminished the ZEA-induced increases in GRP78 and CHOP, and cell death. In summary, our results suggest that ZEA induces the apoptosis and necrosis of RAW 264.7 macrophages in a dose- and time-dependent manner via the ER stress pathway in which the activation of CHOP plays a critical role.

  15. The Batten disease gene CLN3 confers resistance to endoplasmic reticulum stress induced by tunicamycin

    SciTech Connect

    Wu, Dan; Liu, Jing; Wu, Baiyan; Tu, Bo; Zhu, Weiguo; Luo, Jianyuan

    2014-04-25

    Highlights: • The work reveals a protective properties of CLN3 towards TM-induced apoptosis. • CLN3 regulates expression of the GRP78 and the CHOP in response to the ER stress. • CLN3 plays a specific role in the ERS response. - Abstract: Mutations in CLN3 gene cause juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), an early-onset neurodegenerative disorder that is characterized by the accumulation of ceroid lipofuscin within lysosomes. The function of the CLN3 protein remains unclear and is presumed to be related to Endoplasmic reticulum (ER) stress. To investigate the function of CLN3 in the ER stress signaling pathway, we measured proliferation and apoptosis in cells transfected with normal and mutant CLN3 after treatment with the ER stress inducer tunicamycin (TM). We found that overexpression of CLN3 was sufficient in conferring increased resistance to ER stress. Wild-type CLN3 protected cells from TM-induced apoptosis and increased cell proliferation. Overexpression of wild-type CLN3 enhanced expression of the ER chaperone protein, glucose-regulated protein 78 (GRP78), and reduced expression of the proapoptotic protein CCAAT/-enhancer-binding protein homologous protein (CHOP). In contrast, overexpression of mutant CLN3 or siRNA knockdown of CLN3 produced the opposite effect. Together, our data suggest that the lack of CLN3 function in cells leads to a failure of management in the response to ER stress and this may be the key deficit in JNCL that causes neuronal degeneration.

  16. Endoplasmic Reticulum Stress-Sensing Mechanism Is Activated in Entamoeba histolytica upon Treatment with Nitric Oxide

    PubMed Central

    Santi-Rocca, Julien; Smith, Sherri; Weber, Christian; Pineda, Erika; Hon, Chung-Chau; Saavedra, Emma; Olivos-García, Alfonso; Rousseau, Sandrine; Dillies, Marie-Agnès; Coppée, Jean-Yves; Guillén, Nancy

    2012-01-01

    The Endoplasmic Reticulum stores calcium and is a site of protein synthesis and modification. Changes in ER homeostasis lead to stress responses with an activation of the unfolded protein response (UPR). The Entamoeba histolytica endomembrane system is simple compared to those of higher eukaryotes, as a canonical ER is not observed. During amoebiasis, an infection of the human intestine and liver by E. histolytica, nitric oxide (NO) triggers an apoptotic-like event preceded by an impairment of energy production and a loss of important parasite pathogenic features. We address the question of how this ancient eukaryote responds to stress induced by immune components (i.e. NO) and whether stress leads to ER changes and subsequently to an UPR. Gene expression analysis suggested that NO triggers stress responses marked by (i) dramatic up-regulation of hsp genes although a bona fide UPR is absent; (ii) induction of DNA repair and redox gene expression and iii) up-regulation of glycolysis-related gene expression. Enzymology approaches demonstrate that NO directly inhibits glycolysis and enhance cysteine synthase activity. Using live imaging and confocal microscopy we found that NO dramatically provokes extensive ER fragmentation. ER fission in E. histolytica appears as a protective response against stress, as it has been recently proposed for neuron self-defense during neurologic disorders. Chronic ER stress is also involved in metabolic diseases including diabetes, where NO production reduces ER calcium levels and activates cell death. Our data highlighted unique cellular responses of interest to understand the mechanisms of parasite death during amoebiasis. PMID:22384074

  17. Panax quinquefolium saponin attenuates cardiomyocyte apoptosis induced by thapsigargin through inhibition of endoplasmic reticulum stress

    PubMed Central

    Liu, Mi; Xue, Mei; Wang, Xiao-Reng; Tao, Tian-Qi; Xu, Fei-Fei; Liu, Xiu-Hua; Shi, Da-Zhuo

    2015-01-01

    Background Endoplasmic reticulum (ER) stress-related apoptosis is involved in the pathophysiology of many cardiovascular diseases, and Panax quinquefolium saponin (PQS) is able to inhibit excessive ER stress-related apoptosis of cardiomyocytes following hypoxia/reoxygenation and myocardial infarction. However, the pathway by which PQS inhibits the ER stress-related apoptosis is not well understood. To further investigate the protective effect of PQS against ER stress-related apoptosis, primary cultured cardiomyocytes were stimulated with thapsigargin (TG), which is widely used to model cellular ER stress, and it could induce apoptotic cell death in sufficient concentration. Methods Primary cultured cardiomyocytes from neonatal rats were exposed to TG (1 µmol/L) treatment for 24 h, following PQS pre-treatment (160 µg/mL) for 24 h or pre-treatment with small interfering RNA directed against protein kinase-like endoplasmic reticulum kinase (Si-PERK) for 6 h. The viability and apoptosis rate of cardiomyocytes were detected by cell counting kit-8 and flow cytometry respectively. ER stress-related protein expression, such as glucose-regulated protein 78 (GRP78), calreticulin, PERK, eukaryotic translation initiation factor 2α (eIF2α), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP) were assayed by western blotting. Results Both PQS pre-treatment and PERK knockdown remarkably inhibited the cardiomyocyte apoptosis induced by TG, increased cell viability, decreased phosphorylation of both PERK and eIF2α, and decreased protein levels of both ATF4 and CHOP. There was no statistically significant difference between PQS pre-treatment and PERK knockdown in the cardioprotective effect. Conclusions Our data indicate that the PERK-eIF2α-ATF4-CHOP pathway of ER stress is involved in the apoptosis induced by TG, and PQS might prevent TG-induced cardiomyocyte apoptosis through a mechanism involving the suppression of this pathway. These findings

  18. Endoplasmic reticulum stress caused by aggregate-prone proteins containing homopolymeric amino acids.

    PubMed

    Uchio, Naohiro; Oma, Yoko; Toriumi, Kazuya; Sasagawa, Noboru; Tanida, Isei; Fujita, Eriko; Kouroku, Yoriko; Kuroda, Reiko; Momoi, Takashi; Ishiura, Shoichi

    2007-11-01

    Many human proteins have homopolymeric amino acid (HPAA) tracts, but their physiological functions or cellular effects are not well understood. Previously, we expressed 20 HPAAs in mammalian cells and showed characteristic intracellular localization, in that hydrophobic HPAAs aggregated strongly and caused high cytotoxicity in proportion to their hydrophobicity. In the present study, we investigated the cytotoxicity of these aggregate-prone hydrophobic HPAAs, assuming that the ubiquitin proteasome system is impaired in the same manner as other well-known aggregate-prone polyglutamine-containing proteins. Some highly hydrophobic HPAAs caused a deficiency in the ubiquitin proteasome system and excess endoplasmic reticulum stress, leading to apoptosis. These results indicate that the property of causing excess endoplasmic reticulum stress by proteasome impairment may contribute to the strong cytotoxicity of highly hydrophobic HPAAs, and proteasome impairment and the resulting excess endoplasmic reticulum stress is not a common cytotoxic effect of aggregate-prone proteins such as polyglutamine.

  19. Asbestos-induced alveolar epithelial cell apoptosis. The role of endoplasmic reticulum stress response.

    PubMed

    Kamp, David W; Liu, Gang; Cheresh, Paul; Kim, Seok-Jo; Mueller, Amanda; Lam, Anna P; Trejo, Humberto; Williams, David; Tulasiram, Sandhya; Baker, Margaret; Ridge, Karen; Chandel, Navdeep S; Beri, Rohinee

    2013-12-01

    Asbestos exposure results in pulmonary fibrosis (asbestosis) and malignancies (bronchogenic lung cancer and mesothelioma) by mechanisms that are not fully understood. Alveolar epithelial cell (AEC) apoptosis is important in the development of pulmonary fibrosis after exposure to an array of toxins, including asbestos. An endoplasmic reticulum (ER) stress response and mitochondria-regulated (intrinsic) apoptosis occur in AECs of patients with idiopathic pulmonary fibrosis, a disease with similarities to asbestosis. Asbestos induces AEC intrinsic apoptosis, but the role of the ER is unclear. The objective of this study was to determine whether asbestos causes an AEC ER stress response that promotes apoptosis. Using human A549 and rat primary isolated alveolar type II cells, amosite asbestos fibers increased AEC mRNA and protein expression of ER stress proteins involved in the unfolded protein response, such as inositol-requiring kinase (IRE) 1 and X-box-binding protein-1, as well as ER Ca²(2+) release ,as assessed by a FURA-2 assay. Eukarion-134, a superoxide dismutase/catalase mimetic, as well as overexpression of Bcl-XL in A549 cells each attenuate asbestos-induced AEC ER stress (IRE-1 and X-box-binding protein-1 protein expression; ER Ca²(2+) release) and apoptosis. Thapsigargin, a known ER stress inducer, augments AEC apoptosis, and eukarion-134 or Bcl-XL overexpression are protective. Finally, 4-phenylbutyric acid, a chemical chaperone that attenuates ER stress, blocks asbestos- and thapsigargin-induced AEC IRE-1 protein expression, but does not reduce ER Ca²(2+) release or apoptosis. These results show that asbestos triggers an AEC ER stress response and subsequent intrinsic apoptosis that is mediated in part by ER Ca²(2+) release.

  20. Beta Blockers Suppress Dextrose-Induced Endoplasmic Reticulum Stress, Oxidative Stress, and Apoptosis in Human Coronary Artery Endothelial Cells.

    PubMed

    Haas, Michael J; Kurban, William; Shah, Harshit; Onstead-Haas, Luisa; Mooradian, Arshag D

    Beta blockers are known to have favorable effects on endothelial function partly because of their capacity to reduce oxidative stress. To determine whether beta blockers can also prevent dextrose-induced endoplasmic reticulum (ER) stress in addition to their antioxidative effects, human coronary artery endothelial cells and hepatocyte-derived HepG2 cells were treated with 27.5 mM dextrose for 24 hours in the presence of carvedilol (a lipophilic beta blockers with alpha blocking activity), propranolol (a lipophilic nonselective beta blockers), and atenolol (a water-soluble selective beta blockers), and ER stress, oxidative, stress and cell death were measured. ER stress was measured using the placental alkaline phosphatase assay and Western blot analysis of glucose regulated protein 78, c-Jun-N-terminal kinase (JNK), phospho-JNK, eukaryotic initiating factor 2α (eIF2α), and phospho-eIF2α and measurement of X-box binding protein 1 (XBP1) mRNA splicing using reverse transcriptase-polymerase chain reaction. Superoxide (SO) generation was measured using the superoxide-reactive probe 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2-A]pyrazin-3-one hydrochloride (MCLA) chemiluminescence. Cell viability was measured by propidium iodide staining method. The ER stress, SO production, and cell death induced by 27.5 mM dextrose were inhibited by all 3 beta blockers tested. The antioxidative and ER stress reducing effects of beta blockers were also observed in HepG2 cells. The salutary effects of beta blockers on endothelial cells in reducing both ER stress and oxidative stress may contribute to the cardioprotective effects of these agents.

  1. Astragalus polysaccharides attenuate PCV2 infection by inhibiting endoplasmic reticulum stress in vivo and in vitro

    PubMed Central

    Xue, Hongxia; Gan, Fang; Qian, Gang; Hu, Junfa; Hao, Shu; Xu, Jing; Chen, Xingxiang; Huang, Kehe

    2017-01-01

    This study explored the effects of Astragalus polysaccharide (APS) on porcine circovirus type 2 (PCV2) infections and its mechanism in vivo and vitro. First, fifty 2-week-old mice were randomly divided into five groups: a group without PCV2 infection and groups with PCV2 infections at 0, 100, 200 or 400 mg/kg APS treatments. The trial lasted for 28 days. The results showed that APS treatments at 200 and 400 mg/kg reduced the pathological injury of tissues, inhibited PCV2 infection and decreased glucose-regulated protein 78 (GRP78) and GADD153/CHOP gene mRNA and protein expression significantly (P < 0.05). Second, a study on endoplasmic reticulum stress mechanism was carried out in PK15 cells. APS treatments at 15 and 45 μg/mL significantly reduced PCV2 infection and GRP78 mRNA and protein expression (P < 0.05). Tunicamycin supplementation increased GRP78 mRNA and protein expression and significantly attenuated the APS-induced inhibition of PCV2 infection (P < 0.05). Tauroursodeoxycholic acid supplementation decreased GRP78 mRNA and protein expression and significantly inhibited PCV2 infection (P < 0.05). In addition, fifty 2-week-old mice were randomly divided into five groups: Con, PCV2, APS + PCV2, TM + PCV2 and TM + APS + PCV2. The results were similar to those in PK15 cells. Taken together, it could be concluded that APS suppresses PCV2 infection by inhibiting endoplasmic reticulum stress. PMID:28071725

  2. Endoplasmic reticulum stress in the proapoptotic action of edelfosine in solid tumor cells.

    PubMed

    Nieto-Miguel, Teresa; Fonteriz, Rosalba I; Vay, Laura; Gajate, Consuelo; López-Hernández, Silvia; Mollinedo, Faustino

    2007-11-01

    The endoplasmic reticulum (ER) has been posited as a potential anticancer target. The synthetic antitumor alkyl-lysophospholipid analogue edelfosine accumulates in the ER of solid tumor cells. This ER accumulation of the drug leads to the inhibition of phosphatidylcholine and protein synthesis, G(2)-M arrest, depletion of ER-stored Ca(2+), Bax up-regulation and activation, transcriptional factor growth arrest and DNA damage-inducible gene 153 up-regulation, caspase-4 and caspase-8 activation, and eventually to apoptosis. Edelfosine prompted ER stress apoptotic signaling, but not the survival unfolded protein response. Edelfosine also induced persistent c-Jun NH(2)-terminal kinase (JNK) activation. Gene transfer-mediated overexpression of apoptosis signal-regulating kinase 1, which plays a crucial role in ER stress, enhanced edelfosine-induced JNK activation and apoptosis. Inhibition of JNK, caspase-4, or caspase-8 activation diminished edelfosine-induced apoptosis. Edelfosine treatment led to the generation of the p20 caspase-8 cleavage fragment of BAP31, directing proapoptotic signals between the ER and the mitochondria. bax(-/-)bak(-/-) double-knockout cells fail to undergo edelfosine-induced ER-stored Ca(2+) release and apoptosis. Wild-type and bax(-/-)bak(-/-) cells showed similar patterns of phosphatidylcholine and protein synthesis inhibition, despite their differences in drug sensitivity. Thus, edelfosine-induced apoptosis is dependent on Bax/Bak-mediated ER-stored Ca(2+) release, but phosphatidylcholine and protein synthesis inhibition is not critical. Transfection-enforced expression of Bcl-X(L), which localizes specifically in mitochondria, prevented apoptosis without inhibiting ER-stored Ca(2+) release. These data reveal that edelfosine induces an ER stress response in solid tumor cells, providing novel insights into the edelfosine-mediated antitumor activity. Our data also indicate that mitochondria are indispensable for this edelfosine-induced cell

  3. The Dichotomy of Endoplasmic Reticulum Stress Response in Liver Ischemia-Reperfusion Injury.

    PubMed

    Zhou, Haomming; Zhu, Jianjun; Yue, Shi; Lu, Ling; Busuttil, Ronald W; Kupiec-Weglinski, Jerzy W; Wang, Xuehao; Zhai, Yuan

    2016-02-01

    Endoplasmic reticulum (ER) stress plays critical roles in the pathogenesis of liver ischemia-reperfusion injury (IRI). As ER stress triggers an adaptive cellular response, the question of what determines its functional outcome in liver IRI remains to be defined. In a murine liver partial warm ischemia model, we studied how transient (30 minutes) or prolonged (90 minutes) liver ischemia regulated local ER stress response and autophagy activities and their relationship with liver IRI. Effects of chemical chaperon 4-phenylbutyrate (4-PBA) or autophagy inhibitor 3-methyladenine (3-MA) were evaluated. Our results showed that although the activating transcription factor 6 branch of ER stress response was induced in livers by both types of ischemia, liver autophagy was activated by transient, but inhibited by prolonged, ischemia. Although 3-MA had no effects on liver IRI after prolonged ischemia, it significantly increased liver IRI after transient ischemia. The 4-PBA treatment protected livers from IRI after prolonged ischemia by restoring autophagy flux, and the adjunctive 3-MA treatment abrogated its liver protective effect. The same 4-PBA treatment, however, increased liver IRI and disrupted autophagy flux after transient ischemia. Although both types of ischemia activated 5' adenosine monophosphate-activated protein kinase and inactivated protein kinase B (Akt), prolonged ischemia also resulted in downregulations of autophagy-related gene 3 and autophagy-related gene 5 in ischemic livers. These results indicate a functional dichotomy of ER stress response in liver IRI via its regulation of autophagy. Transient ischemia activates autophagy to protect livers from IRI, whereas prolonged ischemia inhibits autophagy to promote the development of liver IRI.

  4. L-carnitine attenuates H2O2-induced neuron apoptosis via inhibition of endoplasmic reticulum stress.

    PubMed

    Ye, Junli; Han, Yantao; Chen, Xuehong; Xie, Jing; Liu, Xiaojin; Qiao, Shunhong; Wang, Chunbo

    2014-12-01

    Both oxidative stress and endoplasmic reticulum stress (ER stress) have been linked to pathogenesis of neurodegenerative diseases. Our previous study has shown that L-carnitine may function as an antioxidant to inhibit H2O2-induced oxidative stress in neuroblastoma SH-SY5Y cells. To further explore the neuroprotection of L-carnitine, here we study the effects of L-carnitine on the ER stress response in H2O2-induced SH-SY5Y cell injury. Our results showed that L-carnitine pretreatment could increase cell viability; inhibit apoptosis and ROS accumulation caused by H2O2 or tunicamycin (TM). L-carnitine suppress the endoplasmic reticulum dilation and activation of ER stress-associated proteins including glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein-homologous protein (CHOP), JNK, Bax and Bim induced by H2O2 or TM. In addition, H2O2-induced cell apoptosis and activation of ER stress can also be attenuated by antioxidant N-acetylcysteine (NAC), CHOP siRNA and the inhibitor of ER stress 4-phenylbutyric acid (4-PBA). Taken together, our results demonstrated that H2O2 could trigger both oxidative stress and ER stress in SH-SY5Y cells, and ER stress participated in SH-SY5Y apoptosis mediated by H2O2-induced oxidative stress. CHOP/Bim or JNK/Bim-dependent ER stress signaling pathways maybe related to the neuroprotective effects of L-carnitine against H2O2-induced apoptosis and oxidative injury.

  5. Efavirenz Causes Oxidative Stress, Endoplasmic Reticulum Stress, and Autophagy in Endothelial Cells.

    PubMed

    Weiß, Marlene; Kost, Bernd; Renner-Müller, Ingrid; Wolf, Eckhard; Mylonas, Ioannis; Brüning, Ansgar

    2016-01-01

    The non-nucleoside reverse transcriptase inhibitor efavirenz is a widely prescribed antiretroviral drug used in combined antiretroviral therapy. Despite being an essential and life-saving medication, the required lifelong use of HIV drugs has been associated with a variety of adverse effects, including disturbances in lipid metabolism and increased cardiovascular risk. Efavirenz belongs to those HIV drugs for which cardiovascular and endothelial dysfunctions have been reported. It is here shown that elevated concentrations of efavirenz can inhibit endothelial meshwork formation on extracellular matrix gels by normal and immortalized human umbilical vein cells. This inhibition was associated with an increase in oxidative stress markers, endoplasmic reticulum (ER) stress markers, and autophagy. Induction of ER stress occurred at pharmacologically relevant concentrations of efavirenz and resulted in reduced proliferation and cell viability of endothelial cells, which worsened in the presence of elevated efavirenz concentrations. In combination with the HIV protease inhibitor nelfinavir, both oxidative stress and ER stress became elevated in endothelial cells. These data indicate that pharmacologically relevant concentrations of efavirenz can impair cell viability of endothelial cells and that these effects may be aggravated by either elevated concentrations of efavirenz or by a combined use of efavirenz with other oxidative stress-inducing medications.

  6. Morphine Protects Spinal Cord Astrocytes from Glutamate-Induced Apoptosis via Reducing Endoplasmic Reticulum Stress.

    PubMed

    Zhang, Chao; Wang, Chendan; Ren, Jianbo; Guo, Xiangjie; Yun, Keming

    2016-10-24

    Glutamate is not only a neurotransmitter but also an important neurotoxin in central nervous system (CNS). Chronic elevation of glutamate induces both neuronal and glial cell apoptosis. However, its effect on astrocytes is complex and still remains unclear. In this study, we investigated whether morphine, a common opioid ligand, could affect glutamate-induced apoptosis in astrocytes. Primary cultured astrocytes were incubated with glutamate in the presence/absence of morphine. It was found that morphine could reduce glutamate-induced apoptosis of astrocytes. Furthermore, glutamate activated Ca(2+) release, thereby inducing endoplasmic reticulum (ER) stress in astrocytes, while morphine attenuated this deleterious effect. Using siRNA to reduce the expression of κ-opioid receptor, morphine could not effectively inhibit glutamate-stimulated Ca(2+) release in astrocytes, the protective effect of morphine on glutamate-injured astrocytes was also suppressed. These results suggested that morphine could protect astrocytes from glutamate-induced apoptosis via reducing Ca(2+) overload and ER stress pathways. In conclusion, this study indicated that excitotoxicity participated in the glutamate mediated apoptosis in astrocytes, while morphine attenuated this deleterious effect via regulating Ca(2+) release and ER stress.

  7. Acidosis Activates Endoplasmic Reticulum Stress Pathways through GPR4 in Human Vascular Endothelial Cells

    PubMed Central

    Dong, Lixue; Krewson, Elizabeth A.; Yang, Li V.

    2017-01-01

    Acidosis commonly exists in the tissue microenvironment of various pathophysiological conditions such as tumors, inflammation, ischemia, metabolic disease, and respiratory disease. For instance, the tumor microenvironment is characterized by acidosis and hypoxia due to tumor heterogeneity, aerobic glycolysis (the “Warburg effect”), and the defective vasculature that cannot efficiently deliver oxygen and nutrients or remove metabolic acid byproduct. How the acidic microenvironment affects the function of blood vessels, however, is not well defined. GPR4 (G protein-coupled receptor 4) is a member of the proton-sensing G protein-coupled receptors and it has high expression in endothelial cells (ECs). We have previously reported that acidosis induces a broad inflammatory response in ECs. Acidosis also increases the expression of several endoplasmic reticulum (ER) stress response genes such as CHOP (C/EBP homologous protein) and ATF3 (activating transcription factor 3). In the current study, we have examined acidosis/GPR4-induced ER stress pathways in human umbilical vein endothelial cells (HUVEC) and other types of ECs. All three arms of the ER stress/unfolded protein response (UPR) pathways were activated by acidosis in ECs as an increased expression of phosphorylated eIF2α (eukaryotic initiation factor 2α), phosphorylated IRE1α (inositol-requiring enzyme 1α), and cleaved ATF6 upon acidic pH treatment was observed. The expression of other downstream mediators of the UPR, such as ATF4, ATF3, and spliced XBP-1 (X box-binding protein 1), was also induced by acidosis. Through genetic and pharmacological approaches to modulate the expression level or activity of GPR4 in HUVEC, we found that GPR4 plays an important role in mediating the ER stress response induced by acidosis. As ER stress/UPR can cause inflammation and cell apoptosis, acidosis/GPR4-induced ER stress pathways in ECs may regulate vascular growth and inflammatory response in the acidic microenvironment

  8. Indium and indium tin oxide induce endoplasmic reticulum stress and oxidative stress in zebrafish (Danio rerio).

    PubMed

    Brun, Nadja Rebecca; Christen, Verena; Furrer, Gerhard; Fent, Karl

    2014-10-07

    Indium and indium tin oxide (ITO) are extensively used in electronic technologies. They may be introduced into the environment during production, use, and leaching from electronic devices at the end of their life. At present, surprisingly little is known about potential ecotoxicological implications of indium contamination. Here, molecular effects of indium nitrate (In(NO3)3) and ITO nanoparticles were investigated in vitro in zebrafish liver cells (ZFL) cells and in zebrafish embryos and novel insights into their molecular effects are provided. In(NO3)3 led to induction of endoplasmic reticulum (ER) stress response, induction of reactive oxygen species (ROS) and induction of transcripts of pro-apoptotic genes and TNF-α in vitro at a concentration of 247 μg/L. In(NO3)3 induced the ER stress key gene BiP at mRNA and protein level, as well as atf6, which ultimately led to induction of the important pro-apoptotic marker gene chop. The activity of In(NO3)3 on ER stress induction was much stronger than that of ITO, which is explained by differences in soluble free indium ion concentrations. The effect was also stronger in ZFL cells than in zebrafish embryos. Our study provides first evidence of ER stress and oxidative stress induction by In(NO3)3 and ITO indicating a critical toxicological profile that needs further investigation.

  9. (-)-Epicatechin mitigates high-fructose-associated insulin resistance by modulating redox signaling and endoplasmic reticulum stress.

    PubMed

    Bettaieb, Ahmed; Vazquez Prieto, Marcela A; Rodriguez Lanzi, Cecilia; Miatello, Roberto M; Haj, Fawaz G; Fraga, César G; Oteiza, Patricia I

    2014-07-01

    We investigated the capacity of dietary (-)-epicatechin (EC) to mitigate insulin resistance through the modulation of redox-regulated mechanisms in a rat model of metabolic syndrome. Adolescent rats were fed a regular chow diet without or with high fructose (HFr; 10% w/v) in drinking water for 8 weeks, and a group of HFr-fed rats was supplemented with EC in the diet. HFr-fed rats developed insulin resistance, which was mitigated by EC supplementation. Accordingly, the activation of components of the insulin signaling cascade (insulin receptor, IRS1, Akt, and ERK1/2) was impaired, whereas negative regulators (PKC, IKK, JNK, and PTP1B) were upregulated in the liver and adipose tissue of HFr rats. These alterations were partially or totally prevented by EC supplementation. In addition, EC inhibited events that contribute to insulin resistance: HFr-associated increased expression and activity of NADPH oxidase, activation of redox-sensitive signals, expression of NF-κB-regulated proinflammatory cytokines and chemokines, and some sub-arms of endoplasmic reticulum stress signaling. Collectively, these findings indicate that EC supplementation can mitigate HFr-induced insulin resistance and are relevant for defining interventions that can prevent/mitigate MetS-associated insulin resistance.

  10. Fluoride-elicited developmental testicular toxicity in rats: roles of endoplasmic reticulum stress and inflammatory response.

    PubMed

    Zhang, Shun; Jiang, Chunyang; Liu, Hongliang; Guan, Zhizhong; Zeng, Qiang; Zhang, Cheng; Lei, Rongrong; Xia, Tao; Gao, Hui; Yang, Lu; Chen, Yihu; Wu, Xue; Zhang, Xiaofei; Cui, Yushan; Yu, Linyu; Wang, Zhenglun; Wang, Aiguo

    2013-09-01

    Long-term excessive fluoride intake is known to be toxic and can damage a variety of organs and tissues in the human body. However, the molecular mechanisms underlying fluoride-induced male reproductive toxicity are not well understood. In this study, we used a rat model to simulate the situations of human exposure and aimed to evaluate the roles of endoplasmic reticulum (ER) stress and inflammatory response in fluoride-induced testicular injury. Sprague-Dawley rats were administered with sodium fluoride (NaF) at 25, 50 and 100mg/L via drinking water from pre-pregnancy to gestation, birth and finally to post-puberty. And then the testes of male offspring were studied at 8weeks of age. Our results demonstrated that fluoride treatment increased MDA accumulation, decreased SOD activity, and enhanced germ cell apoptosis. In addition, fluoride elevated mRNA and protein levels of glucose-regulated protein 78 (GRP78), inositol requiring ER-to-nucleus signal kinase 1 (IRE1), and C/EBP homologous protein (CHOP), indicating activation of ER stress signaling. Furthermore, fluoride also induced testicular inflammation, as manifested by gene up-regulation of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in a nuclear factor-κB (NF-κB)-dependent manner. These were associated with marked histopathological lesions including injury of spermatogonia, decrease of spermatocytes and absence of elongated spermatids, as well as severe ultrastructural abnormalities in testes. Taken together, our results provide compelling evidence that ER stress and inflammation would be novel and significant mechanisms responsible for fluoride-induced disturbance of spermatogenesis and germ cell loss in addition to oxidative stress.

  11. Activation of Toll-like Receptor 4 (TLR4) Attenuates Adaptive Thermogenesis via Endoplasmic Reticulum Stress*

    PubMed Central

    Okla, Meshail; Wang, Wei; Kang, Inhae; Pashaj, Anjeza; Carr, Timothy; Chung, Soonkyu

    2015-01-01

    Adaptive thermogenesis is the cellular process transforming chemical energy into heat in response to cold. A decrease in adaptive thermogenesis is a contributing factor to obesity. However, the molecular mechanisms responsible for the compromised adaptive thermogenesis in obese subjects have not yet been elucidated. In this study we hypothesized that Toll-like receptor 4 (TLR4) activation and subsequent inflammatory responses are key regulators to suppress adaptive thermogenesis. To test this hypothesis, C57BL/6 mice were either fed a palmitate-enriched high fat diet or administered with chronic low-dose LPS before cold acclimation. TLR4 stimulation by a high fat diet or LPS were both associated with reduced core body temperature and heat release. Impairment of thermogenic activation was correlated with diminished expression of brown-specific markers and mitochondrial dysfunction in subcutaneous white adipose tissue (sWAT). Defective sWAT browning was concomitant with elevated levels of endoplasmic reticulum (ER) stress and autophagy. Consistently, TLR4 activation by LPS abolished cAMP-induced up-regulation of uncoupling protein 1 (UCP1) in primary human adipocytes, which was reversed by silencing of C/EBP homologous protein (CHOP). Moreover, the inactivation of ER stress by genetic deletion of CHOP or chemical chaperone conferred a resistance to the LPS-induced suppression of adaptive thermogenesis. Collectively, our data indicate the existence of a novel signaling network that links TLR4 activation, ER stress, and mitochondrial dysfunction, thereby antagonizing thermogenic activation of sWAT. Our results also suggest that TLR4/ER stress axis activation may be a responsible mechanism for obesity-mediated defective brown adipose tissue activation. PMID:26370079

  12. BCL-2 family member BOK promotes apoptosis in response to endoplasmic reticulum stress

    PubMed Central

    Carpio, Marcos A.; Michaud, Michael; Zhou, Wenping; Fisher, Jill K.; Walensky, Loren D.; Katz, Samuel G.

    2015-01-01

    B-cell lymphoma 2 (BCL-2) ovarian killer (BOK) is a BCL-2 family protein with high homology to the multidomain proapoptotic proteins BAX and BAK, yet Bok−/− and even Bax−/−Bok−/− and Bak−/−Bok−/− mice were reported to have no overt phenotype or apoptotic defects in response to a host of classical stress stimuli. These surprising findings were interpreted to reflect functional compensation among the BAX, BAK, and BOK proteins. However, BOK cannot compensate for the severe apoptotic defects of Bax−/−Bak−/− mice despite its widespread expression. Here, we independently developed Bok−/− mice and found that Bok−/− cells are selectively defective in their response to endoplasmic reticulum (ER) stress stimuli, consistent with the predominant subcellular localization of BOK at the ER. Whereas Bok−/− mouse embryonic fibroblasts exposed to thapsigargin, A23187, brefeldin A, DTT, geldanamycin, or bortezomib manifested reduced activation of the mitochondrial apoptotic pathway, the death response to other stimuli such as etoposide, staurosporine, or UV remained fully intact. Multiple organs in Bok−/− mice exhibited resistance to thapsigargin-induced apoptosis in vivo. Although the ER stress agents activated the unfolded protein response, both ATF4 and CHOP activation were diminished in Bok−/− cells and mice. Importantly, BAX and BAK were unable to compensate for the defective apoptotic response to ER stress observed in SV40-transformed and primary Bok−/− cells, and in vivo. These findings support a selective and distinguishing role for BOK in regulating the apoptotic response to ER stress, revealing—to our knowledge—the first bona fide apoptotic defect linked to Bok deletion. PMID:26015568

  13. Sustained endoplasmic reticulum stress inhibits hepatocyte proliferation via downregulation of c-Met expression.

    PubMed

    He, Yihuai; Long, Jun; Zhong, Weiwei; Fu, Yu; Li, Ying; Lin, Shide

    2014-04-01

    The molecular mechanisms of impaired liver regeneration in several liver diseases remain poorly understood. Endoplasmic reticulum (ER) stress has been observed in a variety of liver diseases. The aims of this study were to explore the impacts of ER stress on hepatocyte growth factor (HGF)-induced proliferation and c-Met expression in human hepatocyte L02 cells. Human hepatocyte L02 cells were incubated with thapsigargin (TG) to induce ER stress. 4-Phenylbutyric acid (PBA) was used to rescue ER stress. Activation of glucose-regulated protein 78, phosphorylation of PKR-like ER kinase and eukaryotic translation initiation factor-2α, and the expression of c-Met were determined by western blotting. The expression of c-Met mRNA was observed by reverse transcription polymerase chain reaction. L02 cell proliferation was determined by the MTS assay. L02 cell proliferation was significantly impaired in TG-treated L02 cells from 24 to 48 h, while PBA partly restored the proliferation of L02 cells. In addition, TG treatment significantly decreased the sensitivity of L02 cells to HGF-induced proliferation. PBA partly resumed the sensitivity of L02 cells to HGF-induced proliferation. The expression of c-Met protein in L02 cells was downregulated from 6 h after TG treatment, and PBA partly restored c-Met expression inhibited by TG. The expression of c-Met mRNA was also significantly downregulated from 24 to 48 h after TG treatment. Our results strongly suggest that sustained ER stress inhibits hepatocyte proliferation via downregulation of both c-Met mRNA and protein expression in human hepatocyte L02 cells.

  14. Ischemia-like Oxygen and Glucose Deprivation Mediates Down-regulation of Cell Surface γ-Aminobutyric AcidB Receptors via the Endoplasmic Reticulum (ER) Stress-induced Transcription Factor CCAAT/Enhancer-binding Protein (C/EBP)-homologous Protein (CHOP)*

    PubMed Central

    Maier, Patrick J.; Zemoura, Khaled; Acuña, Mario A.; Yévenes, Gonzalo E.; Zeilhofer, Hanns Ulrich; Benke, Dietmar

    2014-01-01

    Cerebral ischemia frequently leads to long-term disability and death. Excitotoxicity is believed to be the main cause for ischemia-induced neuronal death. Although a role of glutamate receptors in this process has been firmly established, the contribution of metabotropic GABAB receptors, which control excitatory neurotransmission, is less clear. A prominent characteristic of ischemic insults is endoplasmic reticulum (ER) stress associated with the up-regulation of the transcription factor CCAAT/enhancer-binding protein-homologous protein (CHOP). After inducing ER stress in cultured cortical neurons by sustained Ca2+ release from intracellular stores or by a brief episode of oxygen and glucose deprivation (in vitro model of cerebral ischemia), we observed an increased expression of CHOP accompanied by a strong reduction of cell surface GABAB receptors. Our results indicate that down-regulation of cell surface GABAB receptors is caused by the interaction of the receptors with CHOP in the ER. Binding of CHOP prevented heterodimerization of the receptor subunits GABAB1 and GABAB2 and subsequent forward trafficking of the receptors to the cell surface. The reduced level of cell surface receptors diminished GABAB receptor signaling and, thus, neuronal inhibition. These findings indicate that ischemia-mediated up-regulation of CHOP down-regulates cell surface GABAB receptors by preventing their trafficking from the ER to the plasma membrane. This mechanism leads to diminished neuronal inhibition and may contribute to excitotoxicity in cerebral ischemia. PMID:24668805

  15. Severe Injury Is Associated With Insulin Resistance, Endoplasmic Reticulum Stress Response, and Unfolded Protein Response

    PubMed Central

    Jeschke, Marc G.; Finnerty, Celeste C.; Herndon, David N.; Song, Juquan; Boehning, Darren; Tompkins, Ronald G.; Baker, Henry V.; Gauglitz, Gerd G.

    2012-01-01

    Objective We determined whether postburn hyperglycemia and insulin resistance are associated with endoplasmic reticulum (ER) stress/unfolded protein response (UPR) activation leading to impaired insulin receptor signaling. Background Inflammation and cellular stress, hallmarks of severely burned and critically ill patients, have been causally linked to insulin resistance in type 2 diabetes via induction of ER stress and the UPR. Methods Twenty severely burned pediatric patients were compared with 36 nonburned children. Clinical markers, protein, and GeneChip analysis were used to identify transcriptional changes in ER stress and UPR and insulin resistance–related signaling cascades in peripheral blood leukocytes, fat, and muscle at admission and up to 466 days postburn. Results Burn-induced inflammatory and stress responses are accompanied by profound insulin resistance and hyperglycemia. Genomic and protein analysis revealed that burn injury was associated with alterations in the signaling pathways that affect insulin resistance, ER/sarcoplasmic reticulum stress, inflammation, and cell growth/apoptosis up to 466 days postburn. Conclusion Burn-induced insulin resistance is associated with persistent ER/sarcoplasmic reticulum stress/UPR and subsequent suppressed insulin receptor signaling over a prolonged period of time. PMID:22241293

  16. XBP1 mitigates aminoglycoside-induced endoplasmic reticulum stress and neuronal cell death

    PubMed Central

    Oishi, N; Duscha, S; Boukari, H; Meyer, M; Xie, J; Wei, G; Schrepfer, T; Roschitzki, B; Boettger, E C; Schacht, J

    2015-01-01

    Here we study links between aminoglycoside-induced mistranslation, protein misfolding and neuropathy. We demonstrate that aminoglycosides induce misreading in mammalian cells and assess endoplasmic reticulum (ER) stress and unfolded protein response (UPR) pathways. Genome-wide transcriptome and proteome analyses revealed upregulation of genes related to protein folding and degradation. Quantitative PCR confirmed induction of UPR markers including C/EBP homologous protein, glucose-regulated protein 94, binding immunoglobulin protein and X-box binding protein-1 (XBP1) mRNA splicing, which is crucial for UPR activation. We studied the effect of a compromised UPR on aminoglycoside ototoxicity in haploinsufficient XBP1 (XBP1+/−) mice. Intra-tympanic aminoglycoside treatment caused high-frequency hearing loss in XBP1+/− mice but not in wild-type littermates. Densities of spiral ganglion cells and synaptic ribbons were decreased in gentamicin-treated XBP1+/− mice, while sensory cells were preserved. Co-injection of the chemical chaperone tauroursodeoxycholic acid attenuated hearing loss. These results suggest that aminoglycoside-induced ER stress and cell death in spiral ganglion neurons is mitigated by XBP1, masking aminoglycoside neurotoxicity at the organismal level. PMID:25973683

  17. Intracellular Accumulation of Gold Nanoparticles Leads to Inhibition of Macropinocytosis to Reduce the Endoplasmic Reticulum Stress

    NASA Astrophysics Data System (ADS)

    Gunduz, Nuray; Ceylan, Hakan; Guler, Mustafa O.; Tekinay, Ayse B.

    2017-02-01

    Understanding the toxicity of nanomaterials remains largely limited to acute cellular response, i.e., short-term in vitro cell-death based assays, and analyses of tissue- and organ-level accumulation and clearance patterns in animal models, which have produced very little information about how these materials (from the toxicity point of view) interact with the complex intracellular machinery. In particular, understanding the mechanism of toxicity caused by the gradual accumulation of nanomaterials due to prolonged exposure times is essential yet still continue to be a largely unexplored territory. Herein, we show intracellular accumulation and the associated toxicity of gold nanoparticles (AuNPs) for over two-months in the cultured vascular endothelial cells. We observed that steady exposure of AuNPs at low (non-lethal) dose leads to rapid intracellular accumulation without causing any detectable cell death while resulting in elevated endoplasmic reticulum (ER) stress. Above a certain intracellular AuNP threshold, inhibition of macropinocytosis mechanism ceases further nanoparticle uptake. Interestingly, the intracellular depletion of nanoparticles is irreversible. Once reaching the maximum achievable intracellular dose, a steady depletion is observed, while no cell death is observed at any stage of this overall process. This depletion is important for reducing the ER stress. To our knowledge, this is the first report suggesting active regulation of nanoparticle uptake by cells and the impact of long-term exposure to nanoparticles in vitro.

  18. Intracellular Accumulation of Gold Nanoparticles Leads to Inhibition of Macropinocytosis to Reduce the Endoplasmic Reticulum Stress

    PubMed Central

    Gunduz, Nuray; Ceylan, Hakan; Guler, Mustafa O.; Tekinay, Ayse B.

    2017-01-01

    Understanding the toxicity of nanomaterials remains largely limited to acute cellular response, i.e., short-term in vitro cell-death based assays, and analyses of tissue- and organ-level accumulation and clearance patterns in animal models, which have produced very little information about how these materials (from the toxicity point of view) interact with the complex intracellular machinery. In particular, understanding the mechanism of toxicity caused by the gradual accumulation of nanomaterials due to prolonged exposure times is essential yet still continue to be a largely unexplored territory. Herein, we show intracellular accumulation and the associated toxicity of gold nanoparticles (AuNPs) for over two-months in the cultured vascular endothelial cells. We observed that steady exposure of AuNPs at low (non-lethal) dose leads to rapid intracellular accumulation without causing any detectable cell death while resulting in elevated endoplasmic reticulum (ER) stress. Above a certain intracellular AuNP threshold, inhibition of macropinocytosis mechanism ceases further nanoparticle uptake. Interestingly, the intracellular depletion of nanoparticles is irreversible. Once reaching the maximum achievable intracellular dose, a steady depletion is observed, while no cell death is observed at any stage of this overall process. This depletion is important for reducing the ER stress. To our knowledge, this is the first report suggesting active regulation of nanoparticle uptake by cells and the impact of long-term exposure to nanoparticles in vitro. PMID:28145529

  19. The Natural Occurring Compounds Targeting Endoplasmic Reticulum Stress

    PubMed Central

    Liu, Hai; Yang, Jianqiong; Li, Linfu; Shi, Weimei

    2016-01-01

    ER stress has been implicated in pathophysiological development of many diseases. Persistent overwhelming stimuli trigger ER stress to initiate apoptosis, autophagy, and cell death. IRE1-JNK and eIF2α-CHOP signaling pathways are the two important players of ER stress, which is also modulated by ROS production, calcium disturbance, and inflammatory factors. ER stress has been developed as a novel strategy for diseases management. Recently, a vast of research focuses on the natural occurring compounds targeting ER stress, which results in medical benefits to human diseases. These small reported molecules mainly include polyphenols, alkaloids, and saponins. Many of them have been developed for use in clinical applications. To better understand the pharmacological mechanism of these molecules in ER stress in diseases, efforts have been made to discover and deliver medical merits. In this paper, we will summarize the natural occurring compounds targeting ER stress. PMID:27563337

  20. Bifidobacteria Prevent Tunicamycin-Induced Endoplasmic Reticulum Stress and Subsequent Barrier Disruption in Human Intestinal Epithelial Caco-2 Monolayers

    PubMed Central

    Akiyama, Takuya; Oishi, Kenji

    2016-01-01

    Endoplasmic reticulum (ER) stress is caused by accumulation of unfolded and misfolded proteins in the ER, thereby compromising its vital cellular functions in protein production and secretion. Genome wide association studies in humans as well as experimental animal models linked ER stress in intestinal epithelial cells (IECs) with intestinal disorders including inflammatory bowel diseases. However, the mechanisms linking the outcomes of ER stress in IECs to intestinal disease have not been clarified. In this study, we investigated the impact of ER stress on intestinal epithelial barrier function using human colon carcinoma-derived Caco-2 monolayers. Tunicamycin-induced ER stress decreased the trans-epithelial electrical resistance of Caco-2 monolayers, concomitant with loss of cellular plasma membrane integrity. Epithelial barrier disruption in Caco-2 cells after ER stress was not caused by caspase- or RIPK1-dependent cell death but was accompanied by lysosomal rupture and up-regulation of the ER stress markers Grp78, sXBP1 and Chop. Interestingly, several bifidobacteria species inhibited tunicamycin-induced ER stress and thereby diminished barrier disruption in Caco-2 monolayers. Together, these results showed that ER stress compromises the epithelial barrier function of Caco-2 monolayers and demonstrate beneficial impacts of bifidobacteria on ER stress in IECs. Our results identify epithelial barrier loss as a potential link between ER stress and intestinal disease development, and suggest that bifidobacteria could exert beneficial effects on this phenomenon. PMID:27611782

  1. Arsenic induces cell apoptosis in cultured osteoblasts through endoplasmic reticulum stress

    SciTech Connect

    Tang, C.-H.; Chiu, Y.-C.; Huang, C.-F.; Chen, Y.-W.; Chen, P.-C.

    2009-12-01

    Osteoporosis is characterized by low bone mass resulting from an imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Therefore, decreased bone formation by osteoblasts may lead to the development of osteoporosis, and rate of apoptosis is responsible for the regulation of bone formation. Arsenic (As) exists ubiquitously in our environment and increases the risk of neurotoxicity, liver injury, peripheral vascular disease and cancer. However, the effect of As on apoptosis of osteoblasts is mostly unknown. Here, we found that As induced cell apoptosis in osteoblastic cell lines (including hFOB, MC3T3-E1 and MG-63) and mouse bone marrow stromal cells (M2-10B4). As also induced upregulation of Bax and Bak, downregulation of Bcl-2 and dysfunction of mitochondria in osteoblasts. As also triggered endoplasmic reticulum (ER) stress, as indicated by changes in cytosolic-calcium levels. We found that As increased the expression and activities of glucose-regulated protein 78 (GRP78) and calpain. Transfection of cells with GRP78 or calpain siRNA reduced As-mediated cell apoptosis in osteoblasts. Therefore, our results suggest that As increased cell apoptosis in cultured osteoblasts and increased the risk of osteoporosis.

  2. Patenting the gene-hubs of endoplasmic reticulum stress: the systems biology approach.

    PubMed

    Rangel-Aldao, Rafael

    2007-01-01

    An unprecedented and accelerated process of privatizing biological information is emerging from the new techniques of systems biology as they are used to develop novel treatments to key multigenic ailments that account for a large share of mortality world-wide, including cardiovascular disease, cancer, obesity, and diabetes. The systems approach potentially allows the capture of proprietary knowledge at the cross-roads of the flow of biological information preceding these diseases, namely, from the endoplasmic reticulum stress response downstream to inflammation and disease. Although it still holds true that such pathways cannot be patented, methods and chemical substances discussed here are the subject of patents and applications by major research universities and biopharmaceutical companies to a considerable degree of overlapping information. Because biological information pathways are organized into hierarchical networks, the race seems to be on the regulation of the upstream functional modules, and because these complex networks are dominated by gene-hubs and their translation products, the winner will be the one that can appropriate specific and well described methods and substances to control the upper levels of regulation of the entire system. The road to success, however, lays formidable obstacles ahead due to the long and difficult processes separating applications being filed, from patents already issued and these from those that have survived validity litigation. It will be expected that for the sake of mankind, patents pools will be offered to develop novel therapeutics based on the biological information controlled by gene-hubs.

  3. Endoplasmic reticulum-Golgi intermediate compartment protein 3 knockdown suppresses lung cancer through endoplasmic reticulum stress-induced autophagy.

    PubMed

    Hong, Seong-Ho; Chang, Seung-Hee; Cho, Kyung-Cho; Kim, Sanghwa; Park, Sungjin; Lee, Ah Young; Jiang, Hu-Lin; Kim, Hyeon-Jeong; Lee, Somin; Yu, Kyeong-Nam; Seo, Hwi Won; Chae, Chanhee; Kim, Kwang Pyo; Park, Jongsun; Cho, Myung-Haing

    2016-10-04

    Trafficking from the endoplasmic reticulum (ER) to the Golgi apparatus is elevated in cancer cells. Therefore, proteins of the ER-Golgi intermediate compartment (ERGIC) attract significant attention as targets for cancer treatment. Enhanced cancer cell growth and epithelial-mesenchymal transition by ERGICs correlates with poor-prognosis of lung cancer. This prompted us to assess whether knockdown of ERGIC3 may decrease lung cancer growth. To test the hypothesis, the effects of ERGIC3 short hairpin RNA (shERGIC3) on ER stress-induced cell death and lung tumorigenesis were investigated both in vitro and in vivo. Knockdown of ERGIC3 led to ER stress-induced autophagic cell death and suppression of proliferation in the A549 human lung cancer cell-line. Moreover, non-invasive aerosol-delivery of shERGIC3 using the biocompatible carrier glycerol propoxylate triacrylate and spermine (GPT-SPE) inhibited lung tumorigenesis in the K-rasLA1 murine model of lung cancer. Our data suggest that suppression of ERGIC3 could provide a framework for the development of effective lung cancer therapies.

  4. Endoplasmic reticulum-Golgi intermediate compartment protein 3 knockdown suppresses lung cancer through endoplasmic reticulum stress-induced autophagy

    PubMed Central

    Hong, Seong-Ho; Chang, Seung-Hee; Cho, Kyung-Cho; Kim, Sanghwa; Park, Sungjin; Lee, Ah Young; Jiang, Hu-Lin; Kim, Hyeon-Jeong; Lee, Somin; Yu, Kyeong-Nam; Seo, Hwi Won; Chae, Chanhee; Kim, Kwang Pyo; Park, Jongsun; Cho, Myung-Haing

    2016-01-01

    Trafficking from the endoplasmic reticulum (ER) to the Golgi apparatus is elevated in cancer cells. Therefore, proteins of the ER-Golgi intermediate compartment (ERGIC) attract significant attention as targets for cancer treatment. Enhanced cancer cell growth and epithelial-mesenchymal transition by ERGICs correlates with poor-prognosis of lung cancer. This prompted us to assess whether knockdown of ERGIC3 may decrease lung cancer growth. To test the hypothesis, the effects of ERGIC3 short hairpin RNA (shERGIC3) on ER stress-induced cell death and lung tumorigenesis were investigated both in vitro and in vivo. Knockdown of ERGIC3 led to ER stress-induced autophagic cell death and suppression of proliferation in the A549 human lung cancer cell-line. Moreover, non-invasive aerosol-delivery of shERGIC3 using the biocompatible carrier glycerol propoxylate triacrylate and spermine (GPT-SPE) inhibited lung tumorigenesis in the K-rasLA1 murine model of lung cancer. Our data suggest that suppression of ERGIC3 could provide a framework for the development of effective lung cancer therapies. PMID:27588471

  5. Lipocalin-2 Promotes Endoplasmic Reticulum Stress and Proliferation by Augmenting Intracellular Iron in Human Pulmonary Arterial Smooth Muscle Cells

    PubMed Central

    Wang, Guoliang; Liu, Shenghua; Wang, Li; Meng, Liukun; Cui, Chuanjue; Zhang, Hao; Hu, Shengshou; Ma, Ning; Wei, Yingjie

    2017-01-01

    Endoplasmic reticulum (ER) stress, a feature of many conditions associated with pulmonary hypertension (PH), is increasingly recognized as a common response to promote proliferation in the walls of pulmonary arteries. Increased expression of Lipocalin-2 in PH led us to test the hypothesis that Lipocalin-2, a protein known to sequester iron and regulate it intracellularly, might facilitate the ER stress and proliferation in pulmonary arterial smooth muscle cells (PASMCs). In this study, we observed greatly increased Lcn2 expression accompanied with increased ATF6 cleavage in a standard rat model of pulmonary hypertension induced by monocrotaline. In cultured human PASMCs, Lcn2 significantly promoted ER stress (determined by augmented cleavage and nuclear localization of ATF6, up-regulated transcription of GRP78 and NOGO, increased expression of SOD2, and mild augmented mitochondrial membrane potential) and proliferation (assessed by Ki67 staining and BrdU incorporation). Lcn2 promoted ER stress accompanied with augmented intracellular iron levels in human PASMCs. Treatment human PASMCs with FeSO4 induced the similar ER stress and proliferation response and iron chelator (deferoxamine) abrogated the ER stress and proliferation induced by Lcn2 in cultured human PASMCs. In conclusion, Lcn2 significantly promoted human PASMC ER stress and proliferation by augmenting intracellular iron. The up-regulation of Lcn2 probably involved in the pathogenesis and progression of PH. PMID:28255266

  6. Modulation of endoplasmic reticulum stress and cardiomyocyte apoptosis by mulberry leaf diet in experimental autoimmune myocarditis rats

    PubMed Central

    Arumugam, Somasundaram; Thandavarayan, Rajarajan A.; Veeraveedu, Punniyakoti T.; Ma, Meilei; Giridharan, Vijayasree V.; Arozal, Wawaimuli; Sari, Flori R.; Sukumaran, Vijayakumar; Lakshmanan, Arunprasath; Soetikno, Vivian; Suzuki, Kenji; Kodama, Makoto; Watanabe, Kenichi

    2012-01-01

    Mulberry is commonly used as silkworm diet and an alternative medicine in Japan and China, has recently reported to contain many antioxidative flavanoid compounds and having the free radical scavenging effects. Antioxidants reduce cardiac oxidative stress and attenuate cardiac dysfunction in animals with pacing-induced congestive heart failure. Hence we investigated the cardioprotective effect of mulberry leaf powder in rats with experimental autoimmune myocarditis. Eight-week-old Lewis rats immunized with cardiac myosin were fed with either normal chow or a diet containing 5% mulberry leaf powder and were examined on day 21. ML significantly decreased oxidative stress, myocyte apoptosis, cellular infiltration, cardiac fibrosis, mast cell density, myocardial levels of sarco/endo-plasmic reticulum Ca2+ ATPase2, p22phox, receptor for advanced glycation end products, phospho-p38 mitogen activated protein kinase, phospho-c-Jun NH2-terminal protein kinase, glucose regulated protein78, caspase12 and osteopontin levels in EAM rats. These results may suggest that mulberry diet can preserve the cardiac function in experimental autoimmune myocarditis by modulating oxidative stress induced MAPK activation and further afford protection against endoplasmic reticulum stress mediated apoptosis. PMID:22448095

  7. A Phytophthora sojae effector suppresses endoplasmic reticulum stress-mediated immunity by stabilizing plant Binding immunoglobulin Proteins

    PubMed Central

    Jing, Maofeng; Guo, Baodian; Li, Haiyang; Yang, Bo; Wang, Haonan; Kong, Guanghui; Zhao, Yao; Xu, Huawei; Wang, Yan; Ye, Wenwu; Dong, Suomeng; Qiao, Yongli; Tyler, Brett M.; Ma, Wenbo; Wang, Yuanchao

    2016-01-01

    Phytophthora pathogens secrete an array of specific effector proteins to manipulate host innate immunity to promote pathogen colonization. However, little is known about the host targets of effectors and the specific mechanisms by which effectors increase susceptibility. Here we report that the soybean pathogen Phytophthora sojae uses an essential effector PsAvh262 to stabilize endoplasmic reticulum (ER)-luminal binding immunoglobulin proteins (BiPs), which act as negative regulators of plant resistance to Phytophthora. By stabilizing BiPs, PsAvh262 suppresses ER stress-triggered cell death and facilitates Phytophthora infection. The direct targeting of ER stress regulators may represent a common mechanism of host manipulation by microbes. PMID:27256489

  8. Sodium Butyrate Induces Endoplasmic Reticulum Stress and Autophagy in Colorectal Cells: Implications for Apoptosis

    PubMed Central

    Zhang, Jintao; Yi, Man; Zha, Longying; Chen, Siqiang; Li, Zhijia; Li, Cheng; Gong, Mingxing; Deng, Hong; Chu, Xinwei; Chen, Jiehua; Zhang, Zheqing; Mao, Limei; Sun, Suxia

    2016-01-01

    Purpose Butyrate, a short-chain fatty acid derived from dietary fiber, inhibits proliferation and induces cell death in colorectal cancer cells. However, clinical trials have shown mixed results regarding the anti-tumor activities of butyrate. We have previously shown that sodium butyrate increases endoplasmic reticulum stress by altering intracellular calcium levels, a well-known autophagy trigger. Here, we investigated whether sodium butyrate-induced endoplasmic reticulum stress mediated autophagy, and whether there was crosstalk between autophagy and the sodium butyrate-induced apoptotic response in human colorectal cancer cells. Methods Human colorectal cancer cell lines (HCT-116 and HT-29) were treated with sodium butyrate at concentrations ranging from 0.5–5mM. Cell proliferation was assessed using MTT tetrazolium salt formation. Autophagy induction was confirmed through a combination of Western blotting for associated proteins, acridine orange staining for acidic vesicles, detection of autolysosomes (MDC staining), and electron microscopy. Apoptosis was quantified by flow cytometry using standard annexinV/propidium iodide staining and by assessing PARP-1 cleavage by Western blot. Results Sodium butyrate suppressed colorectal cancer cell proliferation, induced autophagy, and resulted in apoptotic cell death. The induction of autophagy was supported by the accumulation of acidic vesicular organelles and autolysosomes, and the expression of autophagy-associated proteins, including microtubule-associated protein II light chain 3 (LC3-II), beclin-1, and autophagocytosis-associated protein (Atg)3. The autophagy inhibitors 3-methyladenine (3-MA) and chloroquine inhibited sodium butyrate induced autophagy. Furthermore, sodium butyrate treatment markedly enhanced the expression of endoplasmic reticulum stress-associated proteins, including BIP, CHOP, PDI, and IRE-1a. When endoplasmic reticulum stress was inhibited by pharmacological (cycloheximide and mithramycin

  9. PFKFB3 modulates glycolytic metabolism and alleviates endoplasmic reticulum stress in human osteoarthritis cartilage.

    PubMed

    Qu, Jining; Lu, Daigang; Guo, Hua; Miao, Wusheng; Wu, Ge; Zhou, Meifen

    2016-03-01

    Glycolytic disorder has been demonstrated to be a major cause of osteoarthritis (OA) and chondrocyte dysfunction. The present work aimed to investigate the expression and role of the glycolytic regulator 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) in OA cartilage. It was found that PFKFB3 expression was down-regulated in human OA cartilage tissues and in tumour necrosis factor (TNF)-α- or interleukin (IL)-1β-stimulated human chondrocytes. The glycolytic metabolism appeared as glucose utilization and adenosine triphosphate (ATP) generation, and lactate production was stunted in OA cartilage. However, the impaired glycolytic process in OA cartilage was improved by PFKFB3 overexpression, which was confirmed in TNF-α- or IL-1β-treated chondrocytes. Furthermore, the expressions of endoplasmic reticulum (ER) stress-associated genes including PERK, ATF3, IRE1, phosphorylated eIF2α (p-eIF2α) and MMP13 were enhanced in OA cartilage explants, while they were decreased by AdPFKFB3 transfection. PFKFB3 also modulated the expressions of PERK, ATF3, IRE1, p-eIF2α and MMP13 in tunicamycin-exposed chondrocytes. Additionally, PFKFB3 improved the cell viability of OA cartilage explants and chondrocytes through the PI3K/Akt/C/EBP homologous protein (CHOP) signalling pathway. The transfection of AdPFKFB3 also significantly reduced caspase 3 activation and promoted aggrecan and type II collagen expressions in OA cartilage explants and chondrocytes. In all, this study characterizes a novel role of PFKFB3 in glycolytic metabolism and ER stress of OA cartilage explants and chondrocytes. The study might provide a potential target for OA prevention or therapy.

  10. Bufalin induces the interplay between apoptosis and autophagy in glioma cells through endoplasmic reticulum stress.

    PubMed

    Shen, Shuying; Zhang, Yi; Wang, Zhen; Liu, Rui; Gong, Xingguo

    2014-01-01

    Malignant gliomas are common primary tumors of the central nervous system. The prognosis of patients with malignant glioma is poor in spite of current intensive therapy and thus novel therapeutic modalities are necessary. Bufalin is the major component of Chan-Su (a traditional Chinese medicine) extracts from the venom of Bufo gargarizan. In this study, we evaluated the growth inhibitory effect of bufalin on glioma cells and explored the underlying molecular mechanisms. Our results showed that bufalin inhibited the growth of glioma cells significantly. Mechanistic studies demonstrated that bufalin induced apoptosis through mitochondrial apoptotic pathway. In addition, bufalin was also found to induce ER stress-mediated apoptosis, which was supported by the up- regulation of ER stress markers, CHOP and GRP78, and augmented phosphorylation of PERK and eIF2α as well as cleavage of caspase-4. Downregulation of CHOP using siCHOP RNA attenuated bufalin-induced apoptosis, further confirming the role of ER stress response in mediating bufalin-induced apoptosis. Evidence of bufalin-induced autophagy included formation of the acidic vesicular organelles, increase of autophagolysosomes and LC3-II accumulation. Further experiments showed that the mechanism of bufalin-induced autophagy associated with ATP deleption involved an increase in the active form of AMPK, decreased phosphorylation levels of mTOR and its downstream targets 4EBP1 and p70S6K1. Furthermore, TUDC and silencing of eIF2α or CHOP partially blocked bufalin-induced accumulation of LC3-II, which indicated that ER stress preceded bufalin-induced autophagy and PERK/eIF2α/CHOP signaling pathway played a major part in the process. Blockage of autophagy increased expression of ER stress associated proteins and the ratio of apoptosis, indicating that autophagy played a cytoprotective role in bufalin induced ER stress and cell death. In conclusion, bufalin inhibits glioma cell growth and induces interplay between

  11. The endoplasmic reticulum stress/autophagy pathway is involved in cholesterol-induced pancreatic β-cell injury

    PubMed Central

    Kong, Fei-Juan; Wu, Jia-Hua; Sun, Shui-Ya; Zhou, Jia-Qiang

    2017-01-01

    Lipotoxicity has been implicated in pancreatic β-cell dysfunction in type 2 diabetes, but the exact mechanisms remain unknown. The current study explored the role of the endoplasmic reticulum (ER) stress pathway in cholesterol-induced lipotoxicity. Two different insulinoma cell lines were treated with cholesterol with or without inhibitors. ER stress-associated proteins glucose-regulated protein (GRP) 78, activating transcription factor (ATF) 4 and C/EBP homologous protein (CHOP), as was phosphorylation of eukaryotic initiation factor (EIF) 2α, were all up-regulated by cholesterol. Cholesterol also up-regulated microtubule-associated protein 1 light chain 3 (LC3)-II and stimulated the formation of autophagic vacuoles and LC3-II aggregates. Cholesterol-induced autophagy and cell injuries were suppressed by pretreatment with the ER stress inhibitor 4-phenylbutyrate (4-PBA). Pretreatment with autophagy inhibitors E-64d/pepstatin A increased ER stress-induced cell injuries as indicated by increased cell apoptosis and decreased insulin secretion. These results suggest that cholesterol treatment induces apoptosis and dysfunction of β-cells, and enhances autophagy through activation of the ER stress pathway. More importantly, autophagy induced by cholesterol may protect β-cells against ER stress-associated cell damages. PMID:28294183

  12. Aging induced endoplasmic reticulum stress alters sleep and sleep homeostasis.

    PubMed

    Brown, Marishka K; Chan, May T; Zimmerman, John E; Pack, Allan I; Jackson, Nicholas E; Naidoo, Nirinjini

    2014-06-01

    Alterations in the quality, quantity, and architecture of baseline and recovery sleep have been shown to occur during aging. Sleep deprivation induces endoplasmic reticular (ER) stress and upregulates a protective signaling pathway termed the unfolded protein response. The effectiveness of the adaptive unfolded protein response is diminished by age. Previously, we showed that endogenous chaperone levels altered recovery sleep in Drosophila melanogaster. We now report that acute administration of the chemical chaperone sodium 4-phenylbutyrate (PBA) reduces ER stress and ameliorates age-associated sleep changes in Drosophila. PBA consolidates both baseline and recovery sleep in aging flies. The behavioral modifications of PBA are linked to its suppression of ER stress. PBA decreased splicing of X-box binding protein 1 and upregulation of phosphorylated elongation initiation factor 2 α, in flies that were subjected to sleep deprivation. We also demonstrate that directly activating ER stress in young flies fragments baseline sleep and alters recovery sleep. Alleviating prolonged or sustained ER stress during aging contributes to sleep consolidation and improves recovery sleep or sleep debt discharge.

  13. Calnexin deficiency and endoplasmic reticulum stress-induced apoptosis.

    PubMed

    Zuppini, Anna; Groenendyk, Jody; Cormack, Lori A; Shore, Gordon; Opas, Michal; Bleackley, R Chris; Michalak, Marek

    2002-02-26

    In this study, we used calnexin-deficient cells to investigate the role of this protein in ER stress-induced apoptosis. We found that calnexin-deficient cells are relatively resistant to ER stress-induced apoptosis. However, caspase 3 and 8 cleavage and cytochrome c release were unchanged in these cells, indicating that ER to mitochondria "communication" during apoptotic stimulation is not affected in the absence of calnexin. The Bcl-2:Bax ratio was also not significantly changed in calnexin-deficient cells regardless of whether the ER stress was induced with thapsigargin or not. Ca(2+) homeostasis and ER morphology were unaffected by the lack of calnexin, but ER stress-induced Bap31 cleavage was significantly inhibited. Immunoprecipitation experiments revealed that Bap31 forms complexes with calnexin, which may play a role in apoptosis. The results suggest that calnexin may not play a role in the initiation of the ER stress but that the protein has an effect on later apoptotic events via its influence on Bap31 function.

  14. Trinitrotoluene Induces Endoplasmic Reticulum Stress and Apoptosis in HePG2 Cells

    PubMed Central

    Song, Li; Wang, Yue; Wang, Jun; Yang, Fan; Li, Xiaojun; Wu, Yonghui

    2015-01-01

    Background This study aims to describe trinitrotoluene (TNT)-induced endoplasmic reticulum stress (ERS) and apoptosis in HePG2 cells. Material/Methods HePG2 cells were cultured in vitro with 0, 6, 12, or 24 μg/ml TNT solution for 12, 24, and 48 h. Western blotting was performed to detect intracellular ERS-related proteins, including glucose-regulated protein (GRP) 78, GRP94, Caspase 4, p-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP). Real-time PCR was used to measure mRNA expression from the respective genes. Results The expressions of ERS-related proteins GRP78 and GRP94 as well as mRNA and protein expression of ERS signaling apoptotic CHOP in the TNT treatment group were significantly increased. In addition, the mRNA and protein expression levels of ERS-induced apoptotic protein Caspase-4 were significantly increased. Flow cytometry revealed that after TNT treatment, the apoptosis rate also significantly increased. Conclusions TNT could increase the expression levels of GRP78, GRP94, Caspase-4, and CHOP in HePG2 cells; this increase in protein expression might be involved in HePG2 apoptosis through the induction of the ERS pathway. PMID:26551326

  15. Reduced Insulin Production Relieves Endoplasmic Reticulum Stress and Induces β Cell Proliferation.

    PubMed

    Szabat, Marta; Page, Melissa M; Panzhinskiy, Evgeniy; Skovsø, Søs; Mojibian, Majid; Fernandez-Tajes, Juan; Bruin, Jennifer E; Bround, Michael J; Lee, Jason T C; Xu, Eric E; Taghizadeh, Farnaz; O'Dwyer, Shannon; van de Bunt, Martijn; Moon, Kyung-Mee; Sinha, Sunita; Han, Jun; Fan, Yong; Lynn, Francis C; Trucco, Massimo; Borchers, Christoph H; Foster, Leonard J; Nislow, Corey; Kieffer, Timothy J; Johnson, James D

    2016-01-12

    Pancreatic β cells are mostly post-mitotic, but it is unclear what locks them in this state. Perturbations including uncontrolled hyperglycemia can drive β cells into more pliable states with reduced cellular insulin levels, increased β cell proliferation, and hormone mis-expression, but it is unknown whether reduced insulin production itself plays a role. Here, we define the effects of ∼50% reduced insulin production in Ins1(-/-):Ins2(f/f):Pdx1Cre(ERT):mTmG mice prior to robust hyperglycemia. Transcriptome, proteome, and network analysis revealed alleviation of chronic endoplasmic reticulum (ER) stress, indicated by reduced Ddit3, Trib3, and Atf4 expression; reduced Xbp1 splicing; and reduced phospho-eIF2α. This state was associated with hyper-phosphorylation of Akt, which is negatively regulated by Trib3, and with cyclinD1 upregulation. Remarkably, β cell proliferation was increased 2-fold after reduced insulin production independently of hyperglycemia. Eventually, recombined cells mis-expressed glucagon in the hyperglycemic state. We conclude that the normally high rate of insulin production suppresses β cell proliferation in a cell-autonomous manner.

  16. Type 2 diabetes mellitus induces congenital heart defects in murine embryos by increasing oxidative stress, endoplasmic reticulum stress, and apoptosis

    PubMed Central

    Wu, Yanqing; Reece, E. Albert; Zhong, Jianxiang; Dong, Daoyin; Shen, Wei-Bin; Harman, Christopher R.; Yang, Peixin

    2017-01-01

    BACKGROUND Maternal type 1 and 2 diabetes mellitus are strongly associated with high rates of severe structural birth defects, including congenital heart defects. Studies in type 1 diabetic embryopathy animal models have demonstrated that cellular stress-induced apoptosis mediates the teratogenicity of maternal diabetes leading to congenital heart defect formation. However, the mechanisms underlying maternal type 2 diabetes mellitus–induced congenital heart defects remain largely unknown. OBJECTIVE We aim to determine whether oxidative stress, endoplasmic reticulum stress, and excessive apoptosis are the intracellular molecular mechanisms underlying maternal type 2 diabetes mellitus–induced congenital heart defects. STUDY DESIGN A mouse model of maternal type 2 diabetes mellitus was established by feeding female mice a high-fat diet (60% fat). After 15 weeks on the high-fat diet, the mice showed characteristics of maternal type 2 diabetes mellitus. Control dams were either fed a normal diet (10% fat) or the high-fat diet during pregnancy only. Female mice from the high-fat diet group and the 2 control groups were mated with male mice that were fed a normal diet. At E12.5, embryonic hearts were harvested to determine the levels of lipid peroxides and superoxide, endoplasmic reticulum stress markers, cleaved caspase 3 and 8, and apoptosis. E17.5 embryonic hearts were harvested for the detection of congenital heart defect formation using India ink vessel patterning and histological examination. RESULTS Maternal type 2 diabetes mellitus significantly induced ventricular septal defects and persistent truncus arteriosus in the developing heart, along with increasing oxidative stress markers, including superoxide and lipid peroxidation; endoplasmic reticulum stress markers, including protein levels of phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase, phosphorylated-IRE1α, phosphorylated-eIF2α, C/EBP homologous protein, and binding immunoglobulin

  17. Nuclear Receptors Resolve Endoplasmic Reticulum Stress to Improve Hepatic Insulin Resistance

    PubMed Central

    2017-01-01

    Chronic endoplasmic reticulum (ER) stress culminating in proteotoxicity contributes to the development of insulin resistance and progression to type 2 diabetes mellitus. Pharmacologic interventions targeting several different nuclear receptors have emerged as potential treatments for insulin resistance. The mechanistic basis for these antidiabetic effects has primarily been attributed to multiple metabolic and inflammatory functions. Here we review recent advances in our understanding of the association of ER stress with insulin resistance and the role of nuclear receptors in promoting ER stress resolution and improving insulin resistance in the liver. PMID:28236381

  18. Impaired autophagic flux is associated with increased endoplasmic reticulum stress during the development of NAFLD

    PubMed Central

    González-Rodríguez, Á; Mayoral, R; Agra, N; Valdecantos, M P; Pardo, V; Miquilena-Colina, M E; Vargas-Castrillón, J; Lo Iacono, O; Corazzari, M; Fimia, G M; Piacentini, M; Muntané, J; Boscá, L; García-Monzón, C; Martín-Sanz, P; Valverde, Á M

    2014-01-01

    The pathogenic mechanisms underlying the progression of non-alcoholic fatty liver disease (NAFLD) are not fully understood. In this study, we aimed to assess the relationship between endoplasmic reticulum (ER) stress and autophagy in human and mouse hepatocytes during NAFLD. ER stress and autophagy markers were analyzed in livers from patients with biopsy-proven non-alcoholic steatosis (NAS) or non-alcoholic steatohepatitis (NASH) compared with livers from subjects with histologically normal liver, in livers from mice fed with chow diet (CHD) compared with mice fed with high fat diet (HFD) or methionine-choline-deficient (MCD) diet and in primary and Huh7 human hepatocytes loaded with palmitic acid (PA). In NASH patients, significant increases in hepatic messenger RNA levels of markers of ER stress (activating transcription factor 4 (ATF4), glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP)) and autophagy (BCN1) were found compared with NAS patients. Likewise, protein levels of GRP78, CHOP and p62/SQSTM1 (p62) autophagic substrate were significantly elevated in NASH compared with NAS patients. In livers from mice fed with HFD or MCD, ER stress-mediated signaling was parallel to the blockade of the autophagic flux assessed by increases in p62, microtubule-associated protein 2 light chain 3 (LC3-II)/LC3-I ratio and accumulation of autophagosomes compared with CHD fed mice. In Huh7 hepatic cells, treatment with PA for 8 h triggered activation of both unfolding protein response and the autophagic flux. Conversely, prolonged treatment with PA (24 h) induced ER stress and cell death together with a blockade of the autophagic flux. Under these conditions, cotreatment with rapamycin or CHOP silencing ameliorated these effects and decreased apoptosis. Our results demonstrated that the autophagic flux is impaired in the liver from both NAFLD patients and murine models of NAFLD, as well as in lipid-overloaded human hepatocytes, and it could be due to

  19. Binge ethanol exposure causes endoplasmic reticulum stress, oxidative stress and tissue injury in the pancreas

    PubMed Central

    Ren, Zhenhua; Wang, Xin; Xu, Mei; Yang, Fanmuyi; Frank, Jacqueline A.; Ke, Zun-ji; Luo, Jia

    2016-01-01

    Alcohol abuse is associated with both acute and chronic pancreatitis. Repeated episodes of acute pancreatitis or pancreatic injury may result in chronic pancreatitis. We investigated ethanol-induced pancreatic injury using a mouse model of binge ethanol exposure. Male C57BL/6 mice were exposed to ethanol intragastrically (5 g/kg, 25% ethanol w/v) daily for 10 days. Binge ethanol exposure caused pathological changes in pancreas demonstrated by tissue edema, acinar atrophy and moderate fibrosis. Ethanol caused both apoptotic and necrotic cell death which was demonstrated by the increase in active caspase-3, caspase-8, cleaved PARP, cleaved CK-18 and the secretion of high mobility group protein B1 (HMGB1). Ethanol altered the function of the pancreas which was indicated by altered levels of alpha-amylase, glucose and insulin. Ethanol exposure stimulated cell proliferation in the acini, suggesting an acinar regeneration. Ethanol caused pancreatic inflammation which was indicated by the induction of TNF-alpha, IL-1beta, IL-6, MCP-1 and CCR2, and the increase of CD68 positive macrophages in the pancreas. Ethanol-induced endoplasmic reticulum stress was demonstrated by a significant increase in ATF6, CHOP, and the phosphorylation of PERK and eiF-2alpha. In addition, ethanol increased protein oxidation, lipid peroxidation and the expression of iNOS, indicating oxidative stress. Therefore, this paradigm of binge ethanol exposure caused a spectrum of tissue injury and cellular stress to the pancreas, offering a good model to study alcoholic pancreatitis. PMID:27527870

  20. Caspase-12 is involved in stretch-induced apoptosis mediated endoplasmic reticulum stress.

    PubMed

    Zhang, Qiang; Liu, Jianing; Chen, Shulan; Liu, Jing; Liu, Lijuan; Liu, Guirong; Wang, Fang; Jiang, Wenxin; Zhang, Caixia; Wang, Shuangyu; Yuan, Xiao

    2016-04-01

    It is well recognized that mandibular growth, which is caused by a variety of functional appliances, is considered to be the result of both neuromuscular and skeletal adaptations. Accumulating evidence has demonstrated that apoptosis plays an important role in the adaptation of skeletal muscle function. However, the underlying mechanism of apoptosis that is induced by stretch continues to be incompletely understood. Endoplasmic reticulum stress (ERS), a newly defined signaling pathway, initiates apoptosis. This study seeks to determine if caspase-12 is involved in stretch-induced apoptosis mediated endoplasmic reticulum stress in myoblast and its underlying mechanism. Apoptosis was assessed by Hochest staining, DAPI staining and annexin V binding and PI staining. ER chaperones, such as GRP78, CHOP and caspase-12, were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Furthermore, caspase-12 inhibitor was used to value the mechanism of the caspase-12 pathway. Apoptosis of myoblast, which is subjected to cyclic stretch, was observed in a time-dependent manner. We found that GRP78 mRNA and protein were significantly increased and CHOP and caspase-12 were activated in myoblast that was exposed to cyclic stretch. Caspase-12 inhibition reduced stretch-induced apoptosis, and caspase-12 activated caspase-3 to induce apoptosis. We concluded that caspase-12 played an important role in stretch-induced apoptosis that is associated by endoplasmic reticulum stress by activating caspase-3.

  1. Endoplasmic reticulum stress contributes to acetylcholine receptor degradation by promoting endocytosis in skeletal muscle cells.

    PubMed

    Du, Ailian; Huang, Shiqian; Zhao, Xiaonan; Zhang, Yun; Zhu, Lixun; Ding, Ji; Xu, Congfeng

    2016-01-15

    After binding by acetylcholine released from a motor neuron, a nicotinic acetylcholine receptor at the neuromuscular junction produces a localized end-plate potential, which leads to muscle contraction. Improper turnover and renewal of acetylcholine receptors contributes to the pathogenesis of myasthenia gravis. In the present study, we demonstrate that endoplasmic reticulum (ER) stress contributes to acetylcholine receptor degradation in C2C12 myocytes. We further show that ER stress promotes acetylcholine receptor endocytosis and lysosomal degradation, which was dampened by blocking endocytosis or treating with lysosome inhibitor. Knockdown of ER stress proteins inhibited acetylcholine receptor endocytosis and degradation, while rescue assay restored its endocytosis and degradation, confirming the effects of ER stress on promoting endocytosis-mediated degradation of junction acetylcholine receptors. Thus, our studies identify ER stress as a factor promoting acetylcholine receptor degradation through accelerating endocytosis in muscle cells. Blocking ER stress and/or endocytosis might provide a novel therapeutic approach for myasthenia gravis.

  2. Mechanisms of alcohol-induced endoplasmic reticulum stress and organ injuries.

    PubMed

    Ji, Cheng

    2012-01-01

    Alcohol is readily distributed throughout the body in the blood stream and crosses biological membranes, which affect virtually all biological processes inside the cell. Excessive alcohol consumption induces numerous pathological stress responses, part of which is endoplasmic reticulum (ER) stress response. ER stress, a condition under which unfolded/misfolded protein accumulates in the ER, contributes to alcoholic disorders of major organs such as liver, pancreas, heart, and brain. Potential mechanisms that trigger the alcoholic ER stress response are directly or indirectly related to alcohol metabolism, which includes toxic acetaldehyde and homocysteine, oxidative stress, perturbations of calcium or iron homeostasis, alterations of S-adenosylmethionine to S-adenosylhomocysteine ratio, and abnormal epigenetic modifications. Interruption of the ER stress triggers is anticipated to have therapeutic benefits for alcoholic disorders.

  3. Endoplasmic reticulum stress as a primary pathogenic mechanism leading to age-related macular degeneration.

    PubMed

    Libby, Richard T; Gould, Douglas B

    2010-01-01

    Age-related macular degeneration (AMD) is a multi-factorial disease and a leading cause of blindness. Proteomic and genetic data suggest that activation or de-repression of the alternate complement cascade of innate immunity is involved in end-stage disease. Several lines of evidence suggest that production of reactive oxygen species and chronic oxidative stress lead to protein and lipid modifications that initiate the complement cascade. Understanding the triggers of these pathogenic pathways and the site of the primary insult will be important for development of targeted therapeutics. Endoplasmic reticulum (ER) stress from misfolded mutant proteins and other sources are an important potential tributary mechanism. We propose that misfolded-protein-induced ER stress in the retinal-pigmented epithelium and/or choroid could lead to chronic oxidative stress, complement deregulation and AMD. Small molecules targeted to ER stress and oxidative stress could allow for a shift from disease treatment to disease prevention.

  4. Endoplasmic reticulum-derived reactive oxygen species (ROS) is involved in toxicity of cell wall stress to Candida albicans.

    PubMed

    Yu, Qilin; Zhang, Bing; Li, Jianrong; Zhang, Biao; Wang, Honggang; Li, Mingchun

    2016-10-01

    The cell wall is an important cell structure in both fungi and bacteria, and hence becomes a common antimicrobial target. The cell wall-perturbing agents disrupt synthesis and function of cell wall components, leading to cell wall stress and consequent cell death. However, little is known about the detailed mechanisms by which cell wall stress renders fungal cell death. In this study, we found that ROS scavengers drastically attenuated the antifungal effect of cell wall-perturbing agents to the model fungal pathogen Candida albicans, and these agents caused remarkable ROS accumulation and activation of oxidative stress response (OSR) in this fungus. Interestingly, cell wall stress did not cause mitochondrial dysfunction and elevation of mitochondrial superoxide levels. Furthermore, the iron chelator 2,2'-bipyridyl (BIP) and the hydroxyl radical scavengers could not attenuate cell wall stress-caused growth inhibition and ROS accumulation. However, cell wall stress up-regulated expression of unfold protein response (UPR) genes, enhanced protein secretion and promoted protein folding-related oxidation of Ero1, an important source of ROS production. These results indicated that oxidation of Ero1 in the endoplasmic reticulum (ER), rather than mitochondrial electron transport and Fenton reaction, contributed to cell wall stress-related ROS accumulation and consequent growth inhibition. Our findings uncover a novel link between cell wall integrity (CWI), ER function and ROS production in fungal cells, and shed novel light on development of strategies promoting the antifungal efficacy of cell wall-perturbing agents against fungal infections.

  5. Metformin prevents endoplasmic reticulum stress-induced apoptosis through AMPK-PI3K-c-Jun NH2 pathway

    USGS Publications Warehouse

    Jung, T.W.; Lee, M.W.; Lee, Y.-J.; Kim, S.M.

    2012-01-01

    Type 2 diabetes mellitus is thought to be partially associated with endoplasmic reticulum (ER) stress toxicity on pancreatic beta cells and the result of decreased insulin synthesis and secretion. In this study, we showed that a well-known insulin sensitizer, metformin, directly protects against dysfunction and death of ER stress-induced NIT-1 cells (a mouse pancreatic beta cell line) via AMP-activated protein kinase (AMPK) and phosphatidylinositol-3 (PI3) kinase activation. We also showed that exposure of NIT-1 cells to metformin (5mM) increases cellular resistance against ER stress-induced NIT-1 cell dysfunction and death. AMPK and PI3 kinase inhibitors abolished the effect of metformin on cell function and death. Metformin-mediated protective effects on ER stress-induced apoptosis were not a result of an unfolded protein response or the induced inhibitors of apoptotic proteins. In addition, we showed that exposure of ER stressed-induced NIT-1 cells to metformin decreases the phosphorylation of c-Jun NH(2) terminal kinase (JNK). These data suggest that metformin is an important determinant of ER stress-induced apoptosis in NIT-1 cells and may have implications for ER stress-mediated pancreatic beta cell destruction via regulation of the AMPK-PI3 kinase-JNK pathway.

  6. Obesity-induced Endoplasmic Reticulum Stress Causes Lung Endothelial Dysfunction and Promotes Acute Lung Injury.

    PubMed

    Shah, Dilip; Romero, Freddy; Guo, Zhi; Sun, Jianxin; Li, Jonathan; Kallen, Caleb B; Naik, Ulhas P; Summer, Ross

    2017-03-09

    Obesity is a significant risk factor for the acute respiratory distress syndrome (ARDS). The mechanisms underlying this association are unknown. We recently showed that diet-induced obese (DIO) mice exhibit pulmonary vascular endothelial dysfunction which is associated with enhanced susceptibility to lipopolysaccharide (LPS)-induced lung injury. Here, we demonstrate that lung endothelial dysfunction in DIO mice coincides with increased endoplasmic reticulum (ER) stress. Specifically, we observed enhanced expression of the major sensors of misfolded proteins including PERK, IREα and ATF6, in whole lung and in lung endothelial cells isolated from DIO mice. Further, we found that lung endothelial cells exposed to serum from obese mice, or to saturated fatty acids that mimic obese serum, resulted in enhanced expression of markers of ER stress and the induction of other biological responses that typify the lung endothelium of DIO mice. Similar changes were observed in lung endothelial cells and in whole lung tissue after exposure to tunicamycin, a compound that causes ER stress by blocking N-linked glycosylation; indicating that ER stress causes endothelial dysfunction in the lung. Treatment with 4-PBA, a chemical protein chaperone that reduces ER stress, restored vascular endothelial cell expression of adhesion molecules and protected against LPS-induced acute lung injury in DIO mice. Our work indicates that fatty acids in obese serum induce ER stress in the pulmonary endothelium leading to pulmonary endothelial cell dysfunction. Our work suggests that reducing protein load in the endoplasmic reticulum of pulmonary endothelial cells might protect against ARDS in obese individuals.

  7. Endoplasmic reticulum stress sensor protein kinase R-like endoplasmic reticulum kinase (PERK) protects against pressure overload-induced heart failure and lung remodeling.

    PubMed

    Liu, Xiaoyu; Kwak, Dongmin; Lu, Zhongbing; Xu, Xin; Fassett, John; Wang, Huan; Wei, Yidong; Cavener, Douglas R; Hu, Xinli; Hall, Jennifer; Bache, Robert J; Chen, Yingjie

    2014-10-01

    Studies have reported that development of congestive heart failure is associated with increased endoplasmic reticulum stress. Double stranded RNA-activated protein kinase R-like endoplasmic reticulum kinase (PERK) is a major transducer of the endoplasmic reticulum stress response and directly phosphorylates eukaryotic initiation factor 2α, resulting in translational attenuation. However, the physiological effect of PERK on congestive heart failure development is unknown. To study the effect of PERK on ventricular structure and function, we generated inducible cardiac-specific PERK knockout mice. Under unstressed conditions, cardiac PERK knockout had no effect on left ventricular mass, or its ratio to body weight, cardiomyocyte size, fibrosis, or left ventricular function. However, in response to chronic transverse aortic constriction, PERK knockout mice exhibited decreased ejection fraction, increased left ventricular fibrosis, enhanced cardiomyocyte apoptosis, and exacerbated lung remodeling in comparison with wild-type mice. PERK knockout also dramatically attenuated cardiac sarcoplasmic reticulum Ca(2+)-ATPase expression in response to aortic constriction. Our findings suggest that PERK is required to protect the heart from pressure overload-induced congestive heart failure.

  8. Calcium homoeostasis modulator 1 (CALHM1) reduces the calcium content of the endoplasmic reticulum (ER) and triggers ER stress.

    PubMed

    Gallego-Sandín, Sonia; Alonso, María Teresa; García-Sancho, Javier

    2011-08-01

    CALHM1 (calcium homoeostasis modulator 1), a membrane protein with similarity to NMDA (N-methyl-D-aspartate) receptor channels that localizes in the plasma membrane and the ER (endoplasmic reticulum) of neurons, has been shown to generate a plasma-membrane Ca(2+) conductance and has been proposed to influence Alzheimer's disease risk. In the present study we have investigated the effects of CALHM1 on intracellular Ca(2+) handling in HEK-293T [HEK (human embryonic kidney)-293 cells expressing the large T-antigen of SV40 (simian virus 40)] cells by using targeted aequorins for selective monitorization of Ca(2+) transport by organelles. We find that CALHM1 increases Ca(2+) leak from the ER and, more importantly, reduces ER Ca(2+) uptake by decreasing both the transport capacity and the Ca(2+) affinity of SERCA (sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase). As a result, the Ca(2+) content of the ER is drastically decreased. This reduction in the Ca(2+) content of the ER triggered the UPR (unfolded protein response) with induction of several ER stress markers, such as CHOP [C/EBP (CCAAT/enhancer-binding protein)-homologous protein], ERdj4, GRP78 (glucose-regulated protein of 78 kDa) and XBP1 (X-box-binding protein 1). Thus CALHM1 might provide a relevant link between Ca(2+) homoeostasis disruption, ER stress and cell damage in the pathogenesis of neurodegenerative diseases.

  9. Endoplasmic reticulum stress-induced autophagy determines the susceptibility of melanoma cells to dabrafenib

    PubMed Central

    Ji, Chao; Zhang, Ziping; Chen, Lihong; Zhou, Kunli; Li, Dongjun; Wang, Ping; Huang, Shuying; Gong, Ting; Cheng, Bo

    2016-01-01

    Melanoma is one of the deadliest skin cancers and accounts for most skin-related deaths due to strong resistance to chemotherapy drugs. In the present study, we investigated the mechanisms of dabrafenib-induced drug resistance in human melanoma cell lines A375 and MEL624. Our studies support that both endoplasmic reticulum (ER) stress and autophagy were induced in the melanoma cells after the treatment with dabrafenib. In addition, ER stress-induced autophagy protects melanoma cells from the toxicity of dabrafenib. Moreover, inhibition of both ER stress and autophagy promote the sensitivity of melanoma cells to dabrafenib. Taken together, the data suggest that ER stress-induced autophagy determines the sensitivity of melanoma cells to dabrafenib. These results provide us with promising evidence that the inhibition of autophagy and ER stress could serve a therapeutic effect for the conventional dabrafenib chemotherapy. PMID:27536070

  10. Endoplasmic reticulum stress-induced autophagy determines the susceptibility of melanoma cells to dabrafenib.

    PubMed

    Ji, Chao; Zhang, Ziping; Chen, Lihong; Zhou, Kunli; Li, Dongjun; Wang, Ping; Huang, Shuying; Gong, Ting; Cheng, Bo

    2016-01-01

    Melanoma is one of the deadliest skin cancers and accounts for most skin-related deaths due to strong resistance to chemotherapy drugs. In the present study, we investigated the mechanisms of dabrafenib-induced drug resistance in human melanoma cell lines A375 and MEL624. Our studies support that both endoplasmic reticulum (ER) stress and autophagy were induced in the melanoma cells after the treatment with dabrafenib. In addition, ER stress-induced autophagy protects melanoma cells from the toxicity of dabrafenib. Moreover, inhibition of both ER stress and autophagy promote the sensitivity of melanoma cells to dabrafenib. Taken together, the data suggest that ER stress-induced autophagy determines the sensitivity of melanoma cells to dabrafenib. These results provide us with promising evidence that the inhibition of autophagy and ER stress could serve a therapeutic effect for the conventional dabrafenib chemotherapy.

  11. Endoplasmic Reticulum Stress Signaling in Mammalian Oocytes and Embryos: Life in the Balance

    PubMed Central

    Latham, Keith E.

    2015-01-01

    Mammalian oocytes and embryos are exquisitely sensitive to a wide range of insults related to physical stress, chemical exposure, and exposures to adverse maternal nutrition or health status. Although cells manifest specific responses to various stressors, many of these stressors intersect at the endoplasmic reticulum, where disruptions in protein folding and production of reactive oxygen species initiate downstream signaling events. These signals modulate mRNA translation and gene transcription, leading to recovery, activation of autophagy, or with severe and prolonged stress, apoptosis. ER stress signaling has recently come to the fore as a major contributor to embryo demise. Accordingly, agents that modulate or inhibit ER stress signaling have yielded beneficial effects on embryo survival and long-term developmental potential. We review here the mechanisms of ER stress signaling, their connections to mammalian oocytes and embryos, and the promising indications that interventions in this pathway may provide new opportunities for improving mammalian reproduction and health. PMID:25805126

  12. Anandamide-induced endoplasmic reticulum stress and apoptosis are mediated by oxidative stress in non-melanoma skin cancer: Receptor-independent endocannabinoid signaling.

    PubMed

    Soliman, Eman; Van Dross, Rukiyah

    2016-11-01

    Endocannabinoids are neuromodulatory lipids that regulate central and peripheral physiological functions. Endocannabinoids have emerged as effective antitumor drugs due to their ability to induce apoptosis in various cancer studies. The G-protein coupled cannabinoid receptors (CB1 and CB2) and the TRPV1 ion channel were reported to mediate the antiproliferative activity of endocannabinoids. However, receptor-independent effects also account for their activity. Our previous studies showed that the antiproliferative activity of anandamide (AEA) was regulated by cyclooxygenase-2 (COX-2) via induction of endoplasmic reticulum (ER) stress. We also determined that AEA induced oxidative stress. However, the role of oxidative stress, the cannabinoid receptors, and TRPV1 in AEA-induced ER stress-apoptosis was unclear. Therefore, the current study examines the role of oxidative stress in ER stress-apoptosis and investigates whether this effect is modulated by CB1, CB2, or TRPV1. In non-melanoma skin cancer (NMSC) cells, AEA reduced the total intracellular level of glutathione and induced oxidative stress. To evaluate the importance of oxidative stress in AEA-induced cell death, the antioxidants, N-acetylcysteine (NAC) and Trolox, were utilized. Each antioxidant ameliorated the antiproliferative effect of AEA. Furthermore, Trolox inhibited AEA-induced CHOP10 expression and caspase 3 activity, indicating that oxidative stress was required for AEA-induced ER stress-apoptosis. On the other hand, selective blockade of CB1, CB2, and TRPV1 did not inhibit AEA-induced oxidative stress or ER stress-apoptosis. These findings suggest that AEA-induced ER stress-apoptosis in NMSC cells is mediated by oxidative stress through a receptor-independent mechanism. Hence, receptor-independent AEA signaling pathways may be targeted to eliminate NMSC. © 2015 Wiley Periodicals, Inc.

  13. Transgenic Overexpression of 14-3-3 Zeta Protects Hippocampus against Endoplasmic Reticulum Stress and Status Epilepticus In Vivo

    PubMed Central

    Brennan, Gary P.; Jimenez-Mateos, Eva M.; McKiernan, Ross C.; Engel, Tobias; Tzivion, Guri; Henshall, David C.

    2013-01-01

    14-3-3 proteins are ubiquitous molecular chaperones that are abundantly expressed in the brain where they regulate cell functions including metabolism, the cell cycle and apoptosis. Brain levels of several 14-3-3 isoforms are altered in diseases of the nervous system, including epilepsy. The 14-3-3 zeta (ζ) isoform has been linked to endoplasmic reticulum (ER) function in neurons, with reduced levels provoking ER stress and increasing vulnerability to excitotoxic injury. Here we report that transgenic overexpression of 14-3-3ζ in mice results in selective changes to the unfolded protein response pathway in the hippocampus, including down-regulation of glucose-regulated proteins 78 and 94, activating transcription factors 4 and 6, and Xbp1 splicing. No differences were found between wild-type mice and transgenic mice for levels of other 14-3-3 isoforms or various other 14-3-3 binding proteins. 14-3-3ζ overexpressing mice were potently protected against cell death caused by intracerebroventricular injection of the ER stressor tunicamycin. 14-3-3ζ overexpressing mice were also potently protected against neuronal death caused by prolonged seizures. These studies demonstrate that increased 14-3-3ζ levels protect against ER stress and seizure-damage despite down-regulation of the unfolded protein response. Delivery of 14-3-3ζ may protect against pathologic changes resulting from prolonged or repeated seizures or where injuries provoke ER stress. PMID:23359526

  14. Tributyltin-induced endoplasmic reticulum stress and its Ca{sup 2+}-mediated mechanism

    SciTech Connect

    Isomura, Midori; Kotake, Yaichiro Masuda, Kyoichi; Miyara, Masatsugu; Okuda, Katsuhiro; Samizo, Shigeyoshi; Sanoh, Seigo; Hosoi, Toru; Ozawa, Koichiro; Ohta, Shigeru

    2013-10-01

    Organotin compounds, especially tributyltin chloride (TBT), have been widely used in antifouling paints for marine vessels, but exhibit various toxicities in mammals. The endoplasmic reticulum (ER) is a multifunctional organelle that controls post-translational modification and intracellular Ca{sup 2+} signaling. When the capacity of the quality control system of ER is exceeded under stress including ER Ca{sup 2+} homeostasis disruption, ER functions are impaired and unfolded proteins are accumulated in ER lumen, which is called ER stress. Here, we examined whether TBT causes ER stress in human neuroblastoma SH-SY5Y cells. We found that 700 nM TBT induced ER stress markers such as CHOP, GRP78, spliced XBP1 mRNA and phosphorylated eIF2α. TBT also decreased the cell viability both concentration- and time-dependently. Dibutyltin and monobutyltin did not induce ER stress markers. We hypothesized that TBT induces ER stress via Ca{sup 2+} depletion, and to test this idea, we examined the effect of TBT on intracellular Ca{sup 2+} concentration using fura-2 AM, a Ca{sup 2+} fluorescent probe. TBT increased intracellular Ca{sup 2+} concentration in a TBT-concentration-dependent manner, and Ca{sup 2+} increase in 700 nM TBT was mainly blocked by 50 μM dantrolene, a ryanodine receptor antagonist (about 70% inhibition). Dantrolene also partially but significantly inhibited TBT-induced GRP78 expression and cell death. These results suggest that TBT increases intracellular Ca{sup 2+} concentration by releasing Ca{sup 2+} from ER, thereby causing ER stress. - Highlights: • We established that tributyltin induces endoplasmic reticulum (ER) stress. • Tributyltin induces ER stress markers in a concentration-dependent manner. • Tributyltin increases Ca{sup 2+} release from ER, thereby causing ER stress. • Dibutyltin and monobutyltin did not increase GRP78 or intracellular Ca{sup 2+}.

  15. Cis-element of the rice PDIL2-3 promoter is responsible for inducing the endoplasmic reticulum stress response.

    PubMed

    Takahashi, Hideyuki; Wang, Shuyi; Hayashi, Shimpei; Wakasa, Yuhya; Takaiwa, Fumio

    2014-05-01

    A protein disulfide isomerase (PDI) family oxidoreductase, PDIL2-3, is involved in endoplasmic reticulum (ER) stress responses in rice. We identified a critical cis-element required for induction of the ER stress response. The activation of PDIL2-3 in response to ER stress strongly depends on the IRE1-OsbZIP50 signaling pathway.

  16. Rescue of Glaucomatous Neurodegeneration by Differentially Modulating Neuronal Endoplasmic Reticulum Stress Molecules

    PubMed Central

    Yang, Liu; Li, Shaohua; Miao, Linqing; Huang, Haoliang; Liang, Feisi; Teng, Xiuyin; Xu, Lin; Wang, Qizhao; Xiao, Weidong; Ridder, William H.; Ferguson, Toby A.; Chen, Dong Feng; Kaufman, Randal J.

    2016-01-01

    Axon injury is an early event in neurodegenerative diseases that often leads to retrograde neuronal cell death and progressive permanent loss of vital neuronal functions. The connection of these two obviously sequential degenerative events, however, is elusive. Deciphering the upstream signals that trigger the neurodegeneration cascades in both neuronal soma and axon would be a key step toward developing the effective neuroprotectants that are greatly needed in the clinic. We showed previously that optic nerve injury-induced neuronal endoplasmic reticulum (ER) stress plays an important role in retinal ganglion cell (RGC) death. Using two in vivo mouse models of optic neuropathies (traumatic optic nerve injury and glaucoma) and adeno-associated virus–mediated RGC-specific gene targeting, we now show that differential manipulation of unfolded protein response pathways in opposite directions—inhibition of eukaryotic translation initiation factor 2α-C/EBP homologous protein and activation of X-box binding protein 1—promotes both RGC axons and somata survival and preserves visual function. Our results indicate that axon injury-induced neuronal ER stress plays an important role in both axon degeneration and neuron soma death. Neuronal ER stress is therefore a promising therapeutic target for glaucoma and potentially other types of neurodegeneration. SIGNIFICANCE STATEMENT Neuron soma and axon degeneration have distinct molecular mechanisms although they are clearly connected after axon injury. We previously demonstrated that axon injury induces neuronal endoplasmic reticulum (ER) stress and that manipulation of ER stress molecules synergistically promotes neuron cell body survival. Here we investigated the possibility that ER stress also plays a role in axon degeneration and whether ER stress modulation preserves neuronal function in neurodegenerative diseases. Our results suggest that neuronal ER stress is a general mechanism of degeneration for both neuronal

  17. Marchantin M Induces Apoptosis of Prostate Cancer Cells Through Endoplasmic Reticulum Stress

    PubMed Central

    Zhang, Tian-Wei; Xing, Li; Tang, Jun-Long; Lu, Jing-Xiao; Liu, Chun-Xiao

    2015-01-01

    Background Apoptosis is mediated by the endoplasmic reticulum (ER) stress pathway, mitochondrial pathway, and death receptor. Data herein suggested an inhibitory effect of marchantin M on tumor formation in nude mice as well as the impact on CHOP and GRP78 expression. Material/Methods The role of marchantin M on proliferation and apoptosis of DU145 cells were measured by MTT and flow cytometry, respectively. Western blot was applied to detect the expression of GRP78 and CHOP. The mice received abdominal injection at 1 time/2 d and 2 ml/time. Tumor volume was measured every 6 days. The mice were euthanatized 30 days after marchantin injection and tumor weight was measured. Cell apoptosis was determined by TUNEL. The expressions of CHOP and GRP78 were detected by immunohistochemistry. Results Tumor size and weight in marchantin groups were significantly lower than in the control group (A, B) (P<0.05), and the inhibitory rate presented a dose-dependent increase. Compared with controls, the levels of CHOP and GRP78 expression elevated obviously following the treatment with marchantin (P<0.05). It showed statistically significant difference among groups C, D, E, with different levels of apoptosis indexes incremented in groups of marchantin H, M, L, compared with groups A and B (P<0.05). Conclusions Overall, this study shows that marchantin M circumvents the growth of prostate cancer PC-3 tumor and up-regulates expressions of CHOP and GRP78. Our data also indicate that marchantin M limits the proliferation and favors apoptosis of DU145 cells in a time- and dose-dependent manner. PMID:26581488

  18. Endoplasmic Reticulum Stress Mediates the Anti-Inflammatory Effect of Ethyl Pyruvate in Endothelial Cells

    PubMed Central

    Yi, Wei; Yang, Yang; Zhao, Dajun; Yang, Honggang; Geng, Ting; Xing, Jianzhou; Zhang, Yu; Tan, Songtao; Yi, Dinghua

    2014-01-01

    Ethyl pyruvate (EP) is a simple aliphatic ester of the metabolic intermediate pyruvate that has been demonstrated to be a potent anti-inflammatory agent in a variety of in vivo and in vitro model systems. However, the protective effects and mechanisms underlying the actions of EP against endothelial cell (EC) inflammatory injury are not fully understood. Previous studies have confirmed that endoplasmic reticulum stress (ERS) plays an important role in regulating the pathological process of EC inflammation. In this study, our aim was to explore the effects of EP on tumor necrosis factor-α (TNF-α)-induced inflammatory injury in human umbilical vein endothelial cells (HUVECs) and to explore the role of ERS in this process. TNF-α treatment not only significantly increased the adhesion of monocytes to HUVECs and inflammatory cytokine (sICAM1, sE-selectin, MCP-1 and IL-8) production in cell culture supernatants but it also increased ICAM and MMP9 protein expression in HUVECs. TNF-α also effectively increased the ERS-related molecules in HUVECs (GRP78, ATF4, caspase12 and p-PERK). EP treatment effectively reversed the effects of the TNF-α-induced adhesion of monocytes on HUVECs, inflammatory cytokines and ERS-related molecules. Furthermore, thapsigargin (THA, an ERS inducer) attenuated the protective effects of EP against TNF-α-induced inflammatory injury and ERS. The PERK siRNA treatment not only inhibited ERS-related molecules but also mimicked the protective effects of EP to decrease TNF-α-induced inflammatory injury. In summary, we have demonstrated for the first time that EP can effectively reduce vascular endothelial inflammation and that this effect at least in part depends on the attenuation of ERS. PMID:25470819

  19. Stress of endoplasmic reticulum modulates differentiation and lipogenesis of human adipocytes

    SciTech Connect

    Koc, Michal; Mayerová, Veronika; Kračmerová, Jana; Mairal, Aline; Mališová, Lucia; Štich, Vladimír; Langin, Dominique; Rossmeislová, Lenka

    2015-05-08

    Background: Adipocytes are cells specialized for storage of neutral lipids. This storage capacity is dependent on lipogenesis and is diminished in obesity. The reason for the decline in lipogenic activity of adipocytes in obesity remains unknown. Recent data show that lipogenesis in liver is regulated by pathways initiated by endoplasmic reticulum stress (ERS). Thus, we aimed at investigating the effect of ERS on lipogenesis in adipose cells. Methods: Preadipocytes were isolated from subcutaneous abdominal adipose tissue from obese volunteers and in vitro differentiated into adipocytes. ERS was induced pharmacologically by thapsigargin (TG) or tunicamycin (TM). Activation of Unfolded Protein Response pathway (UPR) was monitored on the level of eIF2α phosphorylation and mRNA expression of downstream targets of UPR sensors. Adipogenic and lipogenic capacity was evaluated by Oil Red O staining, measurement of incorporation of radio-labelled glucose or acetic acid into lipids and mRNA analysis of adipogenic/lipogenic markers. Results: Exposition of adipocytes to high doses of TG (100 nM) and TM (1 μg/ml) for 1–24 h enhanced expression of several UPR markers (HSPA5, EDEM1, ATF4, XBP1s) and phosphorylation of eIF2α. This acute ERS substantially inhibited expression of lipogenic genes (DGAT2, FASN, SCD1) and glucose incorporation into lipids. Moreover, chronic exposure of preadipocytes to low dose of TG (2.5 nM) during the early phases of adipogenic conversion of preadipocytes impaired both, lipogenesis and adipogenesis. On the other hand, chronic low ERS had no apparent effect on lipogenesis in mature adipocytes. Conclusions: Acute ERS weakened a capacity of mature adipocytes to store lipids and chronic ERS diminished adipogenic potential of preadipocytes. - Highlights: • High intensity ERS inhibits lipogenic capacity of adipocytes. • ERS impairs adipogenesis when present in early stages of adipogenesis. • Lipogenesis in mature adipocytes is not

  20. Melatonin inhibits tunicamycin-induced endoplasmic reticulum stress and insulin resistance in skeletal muscle cells.

    PubMed

    Quan, Xiaojuan; Wang, Juyan; Liang, Chunlian; Zheng, Huadong; Zhang, Lin

    2015-08-07

    The prevalence of type 2 diabetes mellitus (T2D) is increasing worldwide. Melatonin possesses various beneficial metabolic actions, decreased levels of which may accelerate T2D. Endoplasmic reticulum stress (ERS) has been linked to insulin resistance in multiple tissues, but the role of melatonin on ERS and insulin resistance in skeletal muscle has not yet been investigated. In this study, the results showed that tunicamycin decreased insulin-stimulated Akt phosphorylation, but promoted the phosphorylation of protein kinase R-like ER protein kinase (PERK) time-dependently in C2C12 cells. Consistently, ERS gene markers, including binding immunoglobulin protein (BIP)/glucose regulated protein 78 (GRP78) expression and the splicing of X box binding protein 1 (XBP-1), were activated by tunicamycin time-dependently. Interestingly, melatonin pretreatment reversed the elevated PERK phosphorylation, as well as the activation of Bip expression and XBP-1 splicing, and prevented the inhibitory effect of tunicamycin on Akt phosphorylation. In addition, the insulin-provoked glucose transport was reduced by tunicamycin, and then promoted by melatonin pretreatment. A strong phosphorylation of inositol-requiring enzyme 1 (IRE-1), c-JUN NH2-terminal kinase (JNK), and insulin receptor substrate 1 (IRS-1) serine, and simultaneously, a dramatic decrease of IRS-1 tyrosine phosphorylation were observed in the presence of tunicamycin, leading to a blockade of insulin signaling, which was reversed by melatonin pretreatment. Furthermore, luzindole pretreatment acted inversely with melatonin action on glucose uptake and insulin signaling. Therefore, these results demonstrated that melatonin pretreatment inhibited the activated role of tunicamycin on ERS and insulin resistance through melatonin receptor-mediated IRE-1/JNK/IRS-1 insulin signaling in skeletal muscle cells.

  1. Protrudin regulates endoplasmic reticulum morphology and function associated with the pathogenesis of hereditary spastic paraplegia.

    PubMed

    Hashimoto, Yutaka; Shirane, Michiko; Matsuzaki, Fumiko; Saita, Shotaro; Ohnishi, Takafumi; Nakayama, Keiichi I

    2014-05-09

    Protrudin is a membrane protein that regulates polarized vesicular trafficking in neurons. The protrudin gene (ZFYVE27) is mutated in a subset of individuals with hereditary spastic paraplegia (HSP), and protrudin is therefore also referred to as spastic paraplegia (SPG) 33. We have now generated mice that express a transgene for dual epitope-tagged protrudin under control of a neuron-specific promoter, and we have subjected highly purified protrudin-containing complexes isolated from the brain of these mice to proteomics analysis to identify proteins that associate with protrudin. Protrudin was found to interact with other HSP-related proteins including myelin proteolipid protein 1 (SPG2), atlastin-1 (SPG3A), REEP1 (SPG31), REEP5 (similar to REEP1), Kif5A (SPG10), Kif5B, Kif5C, and reticulon 1, 3, and 4 (similar to reticulon 2, SPG12). Membrane topology analysis indicated that one of three hydrophobic segments of protrudin forms a hydrophobic hairpin domain similar to those of other SPG proteins. Protrudin was found to localize predominantly to the tubular endoplasmic reticulum (ER), and forced expression of protrudin promoted the formation and stabilization of the tubular ER network. The protrudin(G191V) mutant, which has been identified in a subset of HSP patients, manifested an increased intracellular stability, and cells expressing this mutant showed an increased susceptibility to ER stress. Our results thus suggest that protrudin contributes to the regulation of ER morphology and function, and that its deregulation by mutation is a causative defect in HSP.

  2. Targeting the hallmarks of cancer with therapy-induced endoplasmic reticulum (ER) stress

    PubMed Central

    Garg, Abhishek D; Maes, Hannelore; van Vliet, Alexander R; Agostinis, Patrizia

    2015-01-01

    The endoplasmic reticulum (ER) is at the center of a number of vital cellular processes such as cell growth, death, and differentiation, crosstalk with immune or stromal cells, and maintenance of proteostasis or homeostasis, and ER functions have implications for various pathologies including cancer. Recently, a number of major hallmarks of cancer have been delineated that are expected to facilitate the development of anticancer therapies. However, therapeutic induction of ER stress as a strategy to broadly target multiple hallmarks of cancer has been seldom discussed despite the fact that several primary or secondary ER stress-inducing therapies have been found to exhibit positive clinical activity in cancer patients. In the present review we provide a brief historical overview of the major discoveries and milestones in the field of ER stress biology with important implications for anticancer therapy. Furthermore, we comprehensively discuss possible strategies enabling the targeting of multiple hallmarks of cancer with therapy-induced ER stress. PMID:27308392

  3. Targeting the hallmarks of cancer with therapy-induced endoplasmic reticulum (ER) stress.

    PubMed

    Garg, Abhishek D; Maes, Hannelore; van Vliet, Alexander R; Agostinis, Patrizia

    2015-01-01

    The endoplasmic reticulum (ER) is at the center of a number of vital cellular processes such as cell growth, death, and differentiation, crosstalk with immune or stromal cells, and maintenance of proteostasis or homeostasis, and ER functions have implications for various pathologies including cancer. Recently, a number of major hallmarks of cancer have been delineated that are expected to facilitate the development of anticancer therapies. However, therapeutic induction of ER stress as a strategy to broadly target multiple hallmarks of cancer has been seldom discussed despite the fact that several primary or secondary ER stress-inducing therapies have been found to exhibit positive clinical activity in cancer patients. In the present review we provide a brief historical overview of the major discoveries and milestones in the field of ER stress biology with important implications for anticancer therapy. Furthermore, we comprehensively discuss possible strategies enabling the targeting of multiple hallmarks of cancer with therapy-induced ER stress.

  4. Endothelial Dysfunction in Diabetes Mellitus: Possible Involvement of Endoplasmic Reticulum Stress?

    PubMed Central

    Basha, Basma; Samuel, Samson Mathews; Triggle, Chris R.; Ding, Hong

    2012-01-01

    The vascular complications of diabetes mellitus impose a huge burden on the management of this disease. The higher incidence of cardiovascular complications and the unfavorable prognosis among diabetic individuals who develop such complications have been correlated to the hyperglycemia-induced oxidative stress and associated endothelial dysfunction. Although antioxidants may be considered as effective therapeutic agents to relieve oxidative stress and protect the endothelium, recent clinical trials involving these agents have shown limited therapeutic efficacy in this regard. In the recent past experimental evidence suggest that endoplasmic reticulum (ER) stress in the endothelial cells might be an important contributor to diabetes-related vascular complications. The current paper contemplates the possibility of the involvement of ER stress in endothelial dysfunction and diabetes-associated vascular complications. PMID:22474423

  5. Soluble forms of polyQ-expanded huntingtin rather than large aggregates cause endoplasmic reticulum stress

    NASA Astrophysics Data System (ADS)

    Leitman, Julia; Ulrich Hartl, F.; Lederkremer, Gerardo Z.

    2013-11-01

    In Huntington’s disease, as in other neurodegenerative diseases, it was initially thought that insoluble protein aggregates are the toxic species. However, growing evidence implicates soluble oligomeric polyglutamine-expanded huntingtin in cytotoxicity. Here we show that pathogenic huntingtin inhibits endoplasmic reticulum (ER)-associated degradation and induces ER stress before its aggregation into visible inclusions. All three branches of the unfolded protein response are activated. ER stress can be compensated by overexpression of p97/VCP, suggesting its sequestration by pathogenic huntingtin as a main cause. Stress correlates with the presence of huntingtin oligomers and is independent of continual huntingtin synthesis. Stress levels, measured in striatal neurons, are stabilized but only slowly subside on huntingtin aggregation into inclusions. Our results can be explained by the constant conversion of huntingtin monomers to toxic oligomers; large aggregates sequester the former, precluding further conversion, whereas pre-existing toxic oligomers are only gradually depleted.

  6. Endothelial dysfunction in diabetes mellitus: possible involvement of endoplasmic reticulum stress?

    PubMed

    Basha, Basma; Samuel, Samson Mathews; Triggle, Chris R; Ding, Hong

    2012-01-01

    The vascular complications of diabetes mellitus impose a huge burden on the management of this disease. The higher incidence of cardiovascular complications and the unfavorable prognosis among diabetic individuals who develop such complications have been correlated to the hyperglycemia-induced oxidative stress and associated endothelial dysfunction. Although antioxidants may be considered as effective therapeutic agents to relieve oxidative stress and protect the endothelium, recent clinical trials involving these agents have shown limited therapeutic efficacy in this regard. In the recent past experimental evidence suggest that endoplasmic reticulum (ER) stress in the endothelial cells might be an important contributor to diabetes-related vascular complications. The current paper contemplates the possibility of the involvement of ER stress in endothelial dysfunction and diabetes-associated vascular complications.

  7. Endoplasmic reticulum stress and its effects on renal tubular cells apoptosis in ischemic acute kidney injury.

    PubMed

    Xu, Yan; Guo, Min; Jiang, Wei; Dong, Hui; Han, Yafei; An, Xiao-Fei; Zhang, Jisheng

    2016-06-01

    Ischemia is the most frequent cause of acute kidney injury (AKI), which is characterized by apoptosis of renal tubular cell. A common result of ischemia in AKI is dysfunction of endoplasmic reticulum (ER), which causes the protein-folding capacity to lag behind the protein-folding load. The abundance of misfolded proteins stressed the ER and results in induction of the unfolded protein response (UPR). While the UPR is an adaptive response, over time it can result in apoptosis when cells are unable to recover quickly. Recent research suggests that ER stress is a major factor in renal tubular cell apoptosis resulting from ischemic AKI. Thus, ER stress may be an important new progression factor in the pathology of ischemic AKI. In this article, we review UPR signaling, describe pathology and pathophysiology mechanisms of ischemic AKI, and highlight the dual function of ER stress on renal tubular cell apoptosis.

  8. Calreticulin and other components of endoplasmic reticulum stress in rat and human inflammatory demyelination

    PubMed Central

    2013-01-01

    Background Calreticulin (CRT) is a chaperone protein, which aids correct folding of glycosylated proteins in the endoplasmic reticulum (ER). Under conditions of ER stress, CRT is upregulated and may be displayed on the surface of cells or be secreted. This ‘ecto-CRT’ may activate the innate immune response or it may aid clearance of apoptotic cells. Our and other studies have demonstrated upregulation of ER stress markers CHOP, BiP, ATF4, XBP1 and phosphorylated e-IF2 alpha (p-eIF2 alpha) in biopsy and post-mortem human multiple sclerosis (MS) samples. We extend this work by analysing changes in expression of CRT, BiP, CHOP, XBP1 and p-eIF2 alpha in a rat model of inflammatory demyelination. Demyelination was induced in the spinal cord by intradermal injection of recombinant mouse MOG mixed with incomplete Freund’s adjuvant (IFA) at the base of the tail. Tissue samples were analysed by semi-quantitative scoring of immunohistochemically stained frozen tissue sections. Data generated following sampling of tissue from animals with spinal cord lesions, was compared to that obtained using tissue derived from IFA- or saline-injected controls. CRT present in rat serum and in a cohort of human serum derived from 14 multiple sclerosis patients and 11 healthy controls was measured by ELISA. Results Stained tissue scores revealed significantly (p<0.05) increased amounts of CRT, CHOP and p-eIF2 alpha in the lesion, lesion edge and normal-appearing white matter when compared to controls. CHOP and p-eIF2 alpha were also significantly raised in regions of grey matter and the central canal (p<0.05). Immunofluorescent dual-label staining confirmed expression of these markers in astrocytes, microglia or neurons. Dual staining of rat and human spinal cord lesions with Oil Red O and CRT antibody showed co-localisation of CRT with the rim of myelin fragments. ELISA testing of sera from control and EAE rats demonstrated significant down-regulation (p<0.05) of CRT in the serum of

  9. AKAP complex regulates Ca2+ re-uptake into heart sarcoplasmic reticulum.

    PubMed

    Lygren, Birgitte; Carlson, Cathrine Rein; Santamaria, Katja; Lissandron, Valentina; McSorley, Theresa; Litzenberg, Jessica; Lorenz, Dorothea; Wiesner, Burkhard; Rosenthal, Walter; Zaccolo, Manuela; Taskén, Kjetil; Klussmann, Enno

    2007-11-01

    The beta-adrenergic receptor/cyclic AMP/protein kinase A (PKA) signalling pathway regulates heart rate and contractility. Here, we identified a supramolecular complex consisting of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2), its negative regulator phospholamban (PLN), the A-kinase anchoring protein AKAP18delta and PKA. We show that AKAP18delta acts as a scaffold that coordinates PKA phosphorylation of PLN and the adrenergic effect on Ca(2+) re-uptake. Inhibition of the compartmentalization of this cAMP signalling complex by specific molecular disruptors interferes with the phosphorylation of PLN. This prevents the subsequent release of PLN from SERCA2, thereby affecting the Ca(2+) re-uptake into the sarcoplasmic reticulum induced by adrenergic stimuli.

  10. Magnetic nanoparticles trigger cell proliferation arrest of neuro-2a cells and ROS-mediated endoplasmic reticulum stress response

    NASA Astrophysics Data System (ADS)

    Wang, Pingping; Chen, Chuanfang; Zeng, Kun; Pan, Weidong; Song, Tao

    2014-11-01

    Magnetic nanoparticles (MNPs) have been increasingly applied in various areas, such as the biomedical and electronic industries. The unique properties of MNPs are beneficial to their applications, but concerns about their safety to human health along with the growing applications and production also arise. In this study, the cytotoxicity of superparamagnetic MNPs, with an average diameter of 10 nm and typical diameter range between 5 and 30 nm, was investigated using neuro-2a cells. The MNPs internalized into the cytoplasm of neuro-2a cells and inhibited the cell viability in a dose-dependent manner at concentrations ranging from 100 to 500 μg/mL. The cell growth inhibition would be partly attributed to the MNP-induced cell cycle arrest in the G0/G1 phase. MNPs triggered the endoplasmic reticulum (ER) stress response, as indicated by the up-regulated expression of the classical ER stress genes, binding immunoglobulin protein, activating transcription factor 6, and CCAAT-enhancer-binding protein homologous protein (CHOP). The induced production of cellular reactive oxygen species (ROS) and increased expression of heme oxygenase 1 and nuclear factor erythroid two-related factor two genes demonstrated that oxidative stress was also induced. Furthermore, the clearance of ROS by free radical scavenger N-acetylcysteine reduced the up-regulation of MNP-induced CHOP mRNA expressions, thereby suggesting that ROS was involved in the process of ER stress response induced by MNPs.

  11. Changes in cellular infrastructure after induced endoplasmic reticulum stress in Moniliophthora perniciosa.

    PubMed

    Basso, Tatiana Setenta; Vita-Santos, Evelyn; Marisco, Gabriele; Pungartnik, Cristina; Brendel, Martin

    2016-09-01

    Moniliophthora perniciosa is a basidiomycete fungus that causes witches' broom disease in Theobroma cacao We analyzed the morphology and survival of fungal hyphae and endoplasmic reticulum (ER) remodeling in either glucose- or glycerol-grown M. perniciosa after treatment with ER stress-inducing chemicals dithiothreitol (DTT) or tunicamycin (TM). Changes in intracellular redox potential can cause endoplasmic reticulum (ER) stress due to diminished efficiency in protein folding that could in turn reduce cell survival. Such stress diminishes protein-folding efficiency that could in turn reduce cell survival. Light microscopy revealed morphological changes in hyphae after TM but not after DTT treatment, regardless of the media carbon source. Decrease in fungal survival, after both TM and DTT treatments, was dose-dependent and glycerol-grown cells showed a higher resistance to both chemicals compared to glucose-grown cells. Electron microscopy showed TM and DDT-induced ER stress in M. perniciosa as evidenced by structural alterations of the organelle. The volume of ER structures increased as a typical consequence of unfolded protein stress, and the number of autophagosomes was higher. In glycerol-grown fungus DTT treatment slightly induced expression of molecular chaperone BiP. The TM exposure-induced expression of gene MpIRE1, involved in signaling of the unfolded protein response, was higher in glycerol than glucose-grown cells. Such difference was not observable with expression of gene MpATG8, encoding a key protein in autosome formation, that was induced 1.4-fold and 1.2-fold in glucose or glycerol-grown cells, respectively. DHE-based fluorescence assay showed M. perniciosa oxidative stress induced by H2O2, and treated cells had a higher level of oxidative stress compared to control. A comprehensive study of remodeling of ER is important in understanding M. perniciosa fungus resistance to oxidative stress and its ability to implement a successful infection in T

  12. Angiogenin Mediates Cell-Autonomous Translational Control under Endoplasmic Reticulum Stress and Attenuates Kidney Injury.

    PubMed

    Mami, Iadh; Bouvier, Nicolas; El Karoui, Khalil; Gallazzini, Morgan; Rabant, Marion; Laurent-Puig, Pierre; Li, Shuping; Tharaux, Pierre-Louis; Beaune, Philippe; Thervet, Eric; Chevet, Eric; Hu, Guo-Fu; Pallet, Nicolas

    2016-03-01

    Endoplasmic reticulum (ER) stress is involved in the pathophysiology of kidney disease and aging, but the molecular bases underlying the biologic outcomes on the evolution of renal disease remain mostly unknown. Angiogenin (ANG) is a ribonuclease that promotes cellular adaptation under stress but its contribution to ER stress signaling remains elusive. In this study, we investigated the ANG-mediated contribution to the signaling and biologic outcomes of ER stress in kidney injury. ANG expression was significantly higher in samples from injured human kidneys than in samples from normal human kidneys, and in mouse and rat kidneys, ANG expression was specifically induced under ER stress. In human renal epithelial cells, ER stress induced ANG expression in a manner dependent on the activity of transcription factor XBP1, and ANG promoted cellular adaptation to ER stress through induction of stress granules and inhibition of translation. Moreover, the severity of renal lesions induced by ER stress was dramatically greater in ANG knockout mice (Ang(-/-)) mice than in wild-type mice. These results indicate that ANG is a critical mediator of tissue adaptation to kidney injury and reveal a physiologically relevant ER stress-mediated adaptive translational control mechanism.

  13. Regulation of lipid metabolism via a connection between the endoplasmic reticulum and lipid droplets.

    PubMed

    Suzuki, Michitaka

    2017-01-01

    Lipid droplets (LDs) are ubiquitous organelles that store and supply lipids to regulate cellular lipid homeostasis. Fatty acids are packaged as triglyceride and cholesterol ester into endoplasmic reticulum (ER) membranes to synthesize LDs. Cytosolic LDs move dynamically and interact with organelles, including other LDs. In this process, functional proteins for metabolism are also transferred to LDs. In this review, I focus on interactions between the ER and LDs related to lipid metabolism.

  14. Saturated lipids decrease mitofusin 2 leading to endoplasmic reticulum stress activation and insulin resistance in hypothalamic cells.

    PubMed

    Diaz, Brenda; Fuentes-Mera, Lizeth; Tovar, Armando; Montiel, Teresa; Massieu, Lourdes; Martínez-Rodríguez, Herminia Guadalupe; Camacho, Alberto

    2015-11-19

    Endoplasmic reticulum (ER) and mitochondria dysfunction contribute to insulin resistance generation during obesity and diabetes. ER and mitochondria interact through Mitofusin 2 (MTF2), which anchors in the outer mitochondrial and ER membranes regulating energy metabolism. Ablation of MTF2 leads to ER stress activation and insulin resistance. Here we determine whether lipotoxic insult induced by saturated lipids decreases MTF2 expression leading to ER stress response in hypothalamus and its effects on insulin sensitivity using in vitro and in vivo models. We found that lipotoxic stimulation induced by palmitic acid, but not the monounsaturated palmitoleic acid, decreases MTF2 protein levels in hypothalamic mHypoA-CLU192 cells. Also, palmitic acid incubation activates ER stress response evidenced by increase in the protein levels of GRP78/BIP marker at later stage than MTF2 downregulation. Additionally, we found that MTF2 alterations induced by palmitic, but not palmitoleic, stimulation exacerbate insulin resistance in hypothalamic cells. Insulin resistance induced by palmitic acid is prevented by pre-incubation of the anti-inflammatory and the ER stress release reagents, sodium salicylate and 4 phenylbutirate, respectively. Finally, we demonstrated that lipotoxic insult induced by high fat feeding to mice decreases MTF2 proteins levels in arcuate nucleus of hypothalamus. Our data indicate that saturated lipids modulate MTF2 expression in hypothalamus coordinating the ER stress response and the susceptibility to insulin resistance.

  15. Inhibition of telomerase causes vulnerability to endoplasmic reticulum stress-induced neuronal cell death.

    PubMed

    Hosoi, Toru; Nakatsu, Kanako; Shimamoto, Akira; Tahara, Hidetoshi; Ozawa, Koichiro

    2016-08-26

    Endoplasmic reticulum (ER) stress is implicated in several diseases, such as cancer and neurodegenerative diseases. In the present study, we investigated the possible involvement of telomerase in ER stress-induced cell death. ER stress-induced cell death was ameliorated in telomerase reverse transcriptase (TERT) over-expressing MCF7 cells (MCF7-TERT cell). Telomerase specific inhibitor, BIBR1532, reversed the inhibitory effect of TERT on ER stress-induced cell death in MCF7-TERT cells. These findings suggest that BIBR1532 may specifically inhibit telomerase activity, thereby inducing cell death in ER stress-exposed cells. TERT was expressed in the SH-SY5Y neuroblastoma cell line. To analyze the possible involvement of telomerase in ER stress-induced neuronal cell death, we treated SH-SY5Y neuroblastoma cells with BIBR1532 and analyzed ER stress-induced cell death. We found that BIBR1532 significantly enhanced the ER stress-induced neuronal cell death. These findings suggest that inhibition of telomerase activity may enhance vulnerability to neuronal cell death caused by ER stress.

  16. The essential biology of the endoplasmic reticulum stress response for structural and computational biologists

    PubMed Central

    Wakabayashi, Sadao; Yoshida, Hiderou

    2013-01-01

    The endoplasmic reticulum (ER) stress response is a cytoprotective mechanism that maintains homeostasis of the ER by upregulating the capacity of the ER in accordance with cellular demands. If the ER stress response cannot function correctly, because of reasons such as aging, genetic mutation or environmental stress, unfolded proteins accumulate in the ER and cause ER stress-induced apoptosis, resulting in the onset of folding diseases, including Alzheimer's disease and diabetes mellitus. Although the mechanism of the ER stress response has been analyzed extensively by biochemists, cell biologists and molecular biologists, many aspects remain to be elucidated. For example, it is unclear how sensor molecules detect ER stress, or how cells choose the two opposite cell fates (survival or apoptosis) during the ER stress response. To resolve these critical issues, structural and computational approaches will be indispensable, although the mechanism of the ER stress response is complicated and difficult to understand holistically at a glance. Here, we provide a concise introduction to the mammalian ER stress response for structural and computational biologists. PMID:24688718

  17. Effect of lithium chloride on endoplasmic reticulum stress-related PERK/ROCK signaling in a rat model of glaucoma.

    PubMed

    Sun, Xiao-Bo; Lu, Hong-E; Chen, Yuan; Fan, Xiao-Hui; Tong, Bin

    2014-12-01

    Elevated intraocular pressure (IOP) is considered as the major risk factor for the loss of retinal ganglion cells (RGCs) and their axons in glaucoma. Lithium chloride (LiCl) inhibits glycogen synthase kinase-3 beta (GSK-3β) and attends PERK-induced endoplasmic reticulum stress (ERs) transition. PERK is a type I transmembrane protein located in the endoplasmic reticulum. PERK pathway activation takes place in ERs early inhibiting protein synthnesis to protect cell and promote cell survival. Here, we firstly evaluate that LiCl reduced IOP when administered intraperitoneally. After 6 weeks, IOP dropped by around 21.9% in LiCl treated rats. Then we investigated the effects of LiCI on PERK-mediated signaling pathways. LiCl treatment activated PERK and inhibited the expression of ROCK-1 and ROCK-2 in a rat model of glaucoma. Collectively, these results suggest that LiCl reduced the IOP through the phosphorylation of PERK by the regulation of PERK/ROCK signaling in glaucoma rat model.

  18. Increased endoplasmic reticulum stress in decidual tissue from pregnancies complicated by fetal growth restriction with and without pre-eclampsia

    PubMed Central

    Lian, I.A.; Løset, M.; Mundal, S.B.; Fenstad, M.H.; Johnson, M.P.; Eide, I.P.; Bjørge, L.; Freed, K.A.; Moses, E.K.; Austgulen, R.

    2011-01-01

    Objectives Endoplasmic reticulum (ER) stress has been implicated in both pre-eclampsia (PE) and fetal growth restriction (FGR), and is characterised by activation of three signalling branches: 1) PERK-pEIF2α, 2) ATF6 and 3) splicing of XBP1(U) into XBP1(S). To evaluate the contribution of ER stress in the pathogenesis of PE relative to FGR, we compared levels of ER stress markers in decidual tissue from pregnancies complicated by PE and/or FGR. Study design Whole-genome transcriptional profiling was performed on decidual tissue from women with PE (n = 13), FGR (n = 9), PE+FGR (n = 24) and controls (n = 58), and used for pathway- and targeted transcriptional analyses of ER stress markers. The expression and cellular localisation of ER stress markers was assesses by Western blot and immunofluorescence analyses. Results Increased ER stress was observed in FGR and PE+FGR, including both the PERK-pEIF2α and ATF6 signalling branches, whereas ER stress was less evident in isolated PE. However, these cases demonstrated elevated levels of XBP1(U) protein. ATF6 and XBP1 immunoreactivity was detected in most (> 80%) extravillous trophoblasts, decidual cells and macrophages. No difference in the proportion of immunopositive cells or staining pattern was observed between study groups. Conclusions Increased PERK-pEIF2α and ATF6 signalling have been associated with decreased cellular proliferation and may contribute to the impaired placental growth characterising pregnancies with FGR and PE+FGR. XBP1(U) has been proposed as a negative regulator of ER stress, and increased levels in PE may reflect a protective mechanism against the detrimental effects of ER stress. PMID:21907405

  19. Coordination of stress, Ca2+, and immunogenic signaling pathways by PERK at the endoplasmic reticulum.

    PubMed

    van Vliet, Alexander R; Garg, Abhishek D; Agostinis, Patrizia

    2016-07-01

    The endoplasmic reticulum (ER) is the main coordinator of intracellular Ca2+ signaling, protein synthesis, and folding. The ER is also implicated in the formation of contact sites with other organelles and structures, including mitochondria, plasma membrane (PM), and endosomes, thereby orchestrating through interorganelle signaling pathways, a variety of cellular responses including Ca2+ homeostasis, metabolism, and cell death signaling. Upon loss of its folding capacity, incited by a number of stress signals including those elicited by various anticancer therapies, the unfolded protein response (UPR) is launched to restore ER homeostasis. The ER stress sensor protein kinase RNA-like ER kinase (PERK) is a key mediator of the UPR and its role during ER stress has been largely recognized. However, growing evidence suggests that PERK may govern signaling pathways through UPR-independent functions. Here, we discuss emerging noncanonical roles of PERK with particular relevance for the induction of danger or immunogenic signaling and interorganelle communication.

  20. Endoplasmic reticulum protein quality control and its relationship to environmental stress responses in plants.

    PubMed

    Liu, Jian-Xiang; Howell, Stephen H

    2010-09-01

    The endoplasmic reticulum (ER) has a sophisticated quality control (QC) system to eliminate improperly folded proteins from the secretory pathway. Given that protein folding is such a fastidious process and subject to adverse environmental conditions, the ER QC system appears to have been usurped to serve as an environmental sensor and responder in plants. Under stressful conditions, the ER protein folding machinery reaches a limit as the demands for protein folding exceed the capacity of the system. Under these conditions, misfolded or unfolded proteins accumulate in the ER, triggering an unfolded protein response (UPR). UPR mitigates ER stress by upregulating the expression of genes encoding components of the protein folding machinery or the ER-associated degradation system. In Arabidopsis thaliana, ER stress is sensed and stress signals are transduced by membrane-bound transcription factors, which are activated and mobilized under environmental stress conditions. Under acute or chronic stress conditions, UPR can also lead to apoptosis or programmed cell death. Despite recent progress in our understanding of plant protein QC, discovering how different environmental conditions are perceived is one of the major challenges in understanding this system. Since the ER QC system is one among many stress response systems in plants, another major challenge is determining the extent to which the ER QC system contributes to various stress responses in plants.

  1. Endothelin receptor-specific control of endoplasmic reticulum stress and apoptosis in the kidney

    PubMed Central

    De Miguel, Carmen; Hamrick, William C.; Hobbs, Janet L.; Pollock, David M.; Carmines, Pamela K.; Pollock, Jennifer S.

    2017-01-01

    Endothelin-1 (ET-1) promotes renal damage during cardiovascular disease; yet, the molecular mechanisms involved remain unknown. Endoplasmic reticulum (ER) stress, triggered by unfolded protein accumulation in the ER, contributes to apoptosis and organ injury. These studies aimed to determine whether the ET-1 system promotes renal ER stress development in response to tunicamycin. ETB deficient (ETB def) or transgenic control (TG-con) rats were used in the presence or absence of ETA receptor antagonism. Tunicamycin treatment similarly increased cortical ER stress markers in both rat genotypes; however, only ETB def rats showed a 14–24 fold increase from baseline for medullary GRP78, sXBP-1, and CHOP. Pre-treatment of TG-con rats with the ETA blocker ABT-627 for 1 week prior to tunicamycin injection significantly reduced the ER stress response in cortex and medulla, and also inhibited renal apoptosis. Pre-treatment with ABT-627 failed to decrease renal ER stress and apoptosis in ETB def rats. In conclusion, the ET-1 system is important for the development of tunicamycin-induced renal ER stress and apoptosis. ETA receptor activation induces renal ER stress genes and apoptosis, while functional activation of the ETB receptor has protective effects. These results highlight targeting the ETA receptor as a therapeutic approach against ER stress-induced kidney injury. PMID:28230089

  2. A critical role of DDRGK1 in endoplasmic reticulum homoeostasis via regulation of IRE1α stability.

    PubMed

    Liu, Jiang; Wang, Ying; Song, Lizhi; Zeng, Linghua; Yi, Weiwei; Liu, Ting; Chen, Huanzhen; Wang, Miao; Ju, Zhenyu; Cong, Yu-Sheng

    2017-01-27

    Disturbance of endoplasmic reticulum (ER) homoeostasis induces ER stress and leads to activation of the unfolded protein response (UPR), which is an adaptive reaction that promotes cell survival or triggers apoptosis, when homoeostasis is not restored. DDRGK1 is an ER membrane protein and a critical component of the ubiquitin-fold modifier 1 (Ufm1) system. However, the functions and mechanisms of DDRGK1 in ER homoeostasis are largely unknown. Here, we show that depletion of DDRGK1 induces ER stress and enhances ER stress-induced apoptosis in both cancer cells and hematopoietic stem cells (HSCs). Depletion of DDRGK1 represses IRE1α-XBP1 signalling and activates the PERK-eIF2α-CHOP apoptotic pathway by targeting the ER-stress sensor IRE1α. We further demonstrate that DDRGK1 regulates IRE1α protein stability via its interaction with the kinase domain of IRE1α, which is dependent on its ufmylation modification. Altogether, our results provide evidence that DDRGK1 is essential for ER homoeostasis regulation.

  3. A critical role of DDRGK1 in endoplasmic reticulum homoeostasis via regulation of IRE1α stability

    PubMed Central

    Liu, Jiang; Wang, Ying; Song, Lizhi; Zeng, Linghua; Yi, Weiwei; Liu, Ting; Chen, Huanzhen; Wang, Miao; Ju, Zhenyu; Cong, Yu-Sheng

    2017-01-01

    Disturbance of endoplasmic reticulum (ER) homoeostasis induces ER stress and leads to activation of the unfolded protein response (UPR), which is an adaptive reaction that promotes cell survival or triggers apoptosis, when homoeostasis is not restored. DDRGK1 is an ER membrane protein and a critical component of the ubiquitin-fold modifier 1 (Ufm1) system. However, the functions and mechanisms of DDRGK1 in ER homoeostasis are largely unknown. Here, we show that depletion of DDRGK1 induces ER stress and enhances ER stress-induced apoptosis in both cancer cells and hematopoietic stem cells (HSCs). Depletion of DDRGK1 represses IRE1α-XBP1 signalling and activates the PERK-eIF2α-CHOP apoptotic pathway by targeting the ER-stress sensor IRE1α. We further demonstrate that DDRGK1 regulates IRE1α protein stability via its interaction with the kinase domain of IRE1α, which is dependent on its ufmylation modification. Altogether, our results provide evidence that DDRGK1 is essential for ER homoeostasis regulation. PMID:28128204

  4. XBP-1 couples endoplasmic reticulum stress to augmented IFN-β induction via a cis-acting enhancer in macrophages

    PubMed Central

    Zeng, Ling; Liu, Yi-Ping; Sha, Haibo; Chen, Hui; Qi, Ling; Smith, Judith A.

    2010-01-01

    Perturbation of the endoplasmic reticulum (ER) results in a conserved stress response called the “Unfolded Protein Response” (UPR). Macrophages undergoing a UPR respond to LPS with log-fold increased production of IFN-β, a cytokine with diverse roles in innate and adaptive immunity. In this report, we found that thapsigargin-induced ER stress augmented recruitment of IRF-3, CBP/p300, and transcriptional machinery to the murine ifnb1 promoter during LPS stimulation. Although full synergistic IFN-β production requires XBP-1, this UPR-regulated transcription factor did not appreciably bind the ifnb1 promoter. However, XBP-1 bound a conserved site 6.1kb downstream of ifnb1, along with IRF-3 and CBP only during concomitant UPR and LPS stimulation. XBP-1 physically associates with p300, suggesting a mechanism of multi-molecular assembly at the +6.1kb site. Luciferase reporter assays provide evidence this +6kb region functions as an XBP-1-dependent enhancer of ifnb1 promoter activity. Thus, this study identifies a novel role for an UPR-dependent transcription factor in the regulation of an inflammatory cytokine. Our findings have broader mechanistic implications for the pathogenesis of diseases involving ER stress and type I interferon, including viral infection, ischemia-reperfusion injury, protein-misfolding and inflammatory diseases. PMID:20660350

  5. Nuclear receptor LRH-1/NR5A2 is required and targetable for liver endoplasmic reticulum stress resolution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chronic endoplasmic reticulum (ER) stress results in toxicity that contributes to multiple human disorders. We report a stress resolution pathway initiated by the nuclear receptor LRH-1 that is independent of known unfolded protein response (UPR) pathways. Like mice lacking primary UPR components, h...

  6. Regulation of Protein Secretion Through Controlled Aggregation in the Endoplasmic Reticulum

    NASA Astrophysics Data System (ADS)

    Rivera, Victor M.; Wang, Xiurong; Wardwell, Scott; Courage, Nancy L.; Volchuk, Allen; Keenan, Terence; Holt, Dennis A.; Gilman, Michael; Orci, Lelio; Cerasoli, Frank; Rothman, James E.; Clackson, Tim

    2000-02-01

    A system for direct pharmacologic control of protein secretion was developed to allow rapid and pulsatile delivery of therapeutic proteins. A protein was engineered so that it accumulated as aggregates in the endoplasmic reticulum. Secretion was then stimulated by a synthetic small-molecule drug that induces protein disaggregation. Rapid and transient secretion of growth hormone and insulin was achieved in vitro and in vivo. A regulated pulse of insulin secretion resulted in a transient correction of serum glucose concentrations in a mouse model of hyperglycemia. This approach may make gene therapy a viable method for delivery of polypeptides that require rapid and regulated delivery.

  7. Algae Undaria pinnatifida Protects Hypothalamic Neurons against Endoplasmic Reticulum Stress through Akt/mTOR Signaling.

    PubMed

    Kim, Jongwan; Moon, Il Soo; Goo, Tae-Won; Moon, Seong-Su; Seo, Minchul

    2015-11-25

    Increased endoplasmic reticulum (ER) stress is known to be one of the causes of hypothalamic neuronal damage, as well as a cause of metabolic disorders such as obesity and diabetes. Recent evidence has suggested that Undaria pinnatifida (UP), an edible brown algae, has antioxidant activity. However, the neuroprotective effect of UP has yet to be examined. In this study, to investigate the neuroprotective effect of UP on ER stress-induced neuronal damage in mouse hypothalamic neurons, mice immortal hypothalamic neurons (GT1-7) were incubated with extract of UP. ER stress was induced by treating with tunicamycin. Tunicamycin induced apoptotic cell death was compared with the vehicle treatment through excessive ER stress. However UP protected GT1-7 cells from cell death, occurring after treatment with tunicamycin by reducing ER stress. Treatment with UP resulted in reduced increment of ATF6 and CHOP, and recovered the decrease of phosphorylation of Akt/mTOR by tunicamycin and the increment of autophagy. These results show that UP protects GT1-7 cells from ER stress induced cell death through the Akt/mTOR pathway. The current study suggests that UP may have a beneficial effect on cerebral neuronal degeneration in metabolic diseases with elevated ER stress.

  8. Galangin inhibits proliferation of hepatocellular carcinoma cells by inducing endoplasmic reticulum stress.

    PubMed

    Su, Lijuan; Chen, Xiaoyi; Wu, Jun; Lin, Biyun; Zhang, Haitao; Lan, Liubo; Luo, Hui

    2013-12-01

    Prolonged endoplasmic reticulum (ER) stress may activate apoptotic pathways in cancer cells. It is suggested that ER stress has the potential of enhancing tumor death in cancer therapy. Galangin, a flavonol derived from Alpinia officinarum Hance, has been shown to suppress the proliferation of hepatocellular carcinoma cells (HCC). The aim of this study was to determine whether galangin was able to induce ER stress in HepG2, Hep3B and PLC/PRF/5 cells. The proliferation of HCC was tested by MTT method. Intracellular Ca(2+) levels were measured with Fluo3-AM.The proteins levels of GRP94, GRP78 and CHOP were detected by Western blot. To further understand the anti-HCC mechanism of galangin, mitogen-activated protein kinases (MAPKs) were detected. The results showed that galangin treatment induced ER stress was evidenced by increased protein levels of GRP94, GRP78 and CHOP, as well as increased free cytosolic Ca(2+) concentration. ER stress inhibitor 4-PBA and CHOP siRNA blocked significantly galangin-induced ER in all three cell lines. Further experiments showed that MAPKs involved in ER stress induced by galangin. In summary, galangin is identified as a stimulator of ER stress to suppress the proliferation of HCC, and may be used as a potential anti-cancer agent.

  9. Inhibition of endoplasmic reticulum stress improves coronary artery function in the spontaneously hypertensive rats

    PubMed Central

    Choi, Soo-Kyoung; Lim, Mihwa; Byeon, Seon-Hee; Lee, Young-Ho

    2016-01-01

    Endoplasmic reticulum (ER) stress has been shown to play a critical role in the pathogenesis of cardiovascular complications. However, the role and mechanisms of ER stress in hypertension remain unclear. Thus, we hypothesized that enhanced ER stress contributes to the maintenance of hypertension in spontaneously hypertensive rats (SHRs). Sixteen-week old male SHRs and Wistar Kyoto Rats (WKYs) were used in this study. The SHRs were treated with ER stress inhibitor (Tauroursodeoxycholic acid; TUDCA, 100 mg/kg/day) for two weeks. There was a decrease in systolic blood pressure in SHR treated with TUDCA. The pressure-induced myogenic tone was significantly increased, whereas endothelium-dependent relaxation was significantly attenuated in SHR compared with WHY. Interestingly, treatment of ER stress inhibitor normalized myogenic responses and endothelium-dependent relaxation in SHR. These data were associated with an increase in expression or phosphorylation of ER stress markers (Bip, ATF6, CHOP, IRE1, XBP1, PERK, and eIF2α) in SHRs, which were reduced by TUDCA treatment. Furthermore, phosphorylation of MLC20 was increased in SHRs, which was reduced by the treatment of TUDCA. Therefore, our results suggest that ER stress could be a potential target for hypertension. PMID:27550383

  10. Endoplasmic Reticulum (ER) Stress Induces Sirtuin 1 (SIRT1) Expression via the PI3K-Akt-GSK3β Signaling Pathway and Promotes Hepatocellular Injury.

    PubMed

    Koga, Tomoaki; Suico, Mary Ann; Shimasaki, Shogo; Watanabe, Eriko; Kai, Yukari; Koyama, Kosuke; Omachi, Kohei; Morino-Koga, Saori; Sato, Takashi; Shuto, Tsuyoshi; Mori, Kazutoshi; Hino, Shinjiro; Nakao, Mitsuyoshi; Kai, Hirofumi

    2015-12-18

    Sirtuin 1 (SIRT1), an NAD(+)-dependent histone deacetylase, plays crucial roles in various biological processes including longevity, stress response, and cell survival. Endoplasmic reticulum (ER) stress is caused by dysfunction of ER homeostasis and exacerbates various diseases including diabetes, fatty liver, and chronic obstructive pulmonary disease. Although several reports have shown that SIRT1 negatively regulates ER stress and ER stress-induced responses in vitro and in vivo, the effect of ER stress on SIRT1 is less explored. In this study, we showed that ER stress induced SIRT1 expression in vitro and in vivo. We further determined the molecular mechanisms of how ER stress induces SIRT1 expression. Surprisingly, the conventional ER stress-activated transcription factors XBP1, ATF4, and ATF6 seem to be dispensable for SIRT1 induction. Based on inhibitor screening experiments with SIRT1 promoter, we found that the PI3K-Akt-GSK3β signaling pathway is required for SIRT1 induction by ER stress. Moreover, we showed that pharmacological inhibition of SIRT1 by EX527 inhibited the ER stress-induced cellular death in vitro and severe hepatocellular injury in vivo, indicating a detrimental role of SIRT1 in ER stress-induced damage responses. Collectively, these data suggest that SIRT1 expression is up-regulated by ER stress and contributes to ER stress-induced cellular damage.

  11. Endoplasmic Reticulum (ER) Stress Induces Sirtuin 1 (SIRT1) Expression via the PI3K-Akt-GSK3β Signaling Pathway and Promotes Hepatocellular Injury*

    PubMed Central

    Koga, Tomoaki; Suico, Mary Ann; Shimasaki, Shogo; Watanabe, Eriko; Kai, Yukari; Koyama, Kosuke; Omachi, Kohei; Morino-Koga, Saori; Sato, Takashi; Shuto, Tsuyoshi; Mori, Kazutoshi; Hino, Shinjiro; Nakao, Mitsuyoshi; Kai, Hirofumi

    2015-01-01

    Sirtuin 1 (SIRT1), an NAD+-dependent histone deacetylase, plays crucial roles in various biological processes including longevity, stress response, and cell survival. Endoplasmic reticulum (ER) stress is caused by dysfunction of ER homeostasis and exacerbates various diseases including diabetes, fatty liver, and chronic obstructive pulmonary disease. Although several reports have shown that SIRT1 negatively regulates ER stress and ER stress-induced responses in vitro and in vivo, the effect of ER stress on SIRT1 is less explored. In this study, we showed that ER stress induced SIRT1 expression in vitro and in vivo. We further determined the molecular mechanisms of how ER stress induces SIRT1 expression. Surprisingly, the conventional ER stress-activated transcription factors XBP1, ATF4, and ATF6 seem to be dispensable for SIRT1 induction. Based on inhibitor screening experiments with SIRT1 promoter, we found that the PI3K-Akt-GSK3β signaling pathway is required for SIRT1 induction by ER stress. Moreover, we showed that pharmacological inhibition of SIRT1 by EX527 inhibited the ER stress-induced cellular death in vitro and severe hepatocellular injury in vivo, indicating a detrimental role of SIRT1 in ER stress-induced damage responses. Collectively, these data suggest that SIRT1 expression is up-regulated by ER stress and contributes to ER stress-induced cellular damage. PMID:26499802

  12. Endoplasmic reticulum stress-mediated hippocampal neuron apoptosis involved in diabetic cognitive impairment.

    PubMed

    Zhang, Xiaoming; Xu, Linhao; He, Daqiang; Ling, Shucai

    2013-01-01

    Poor management of DM causes cognitive impairment while the mechanism is still unconfirmed. The aim of the present study was to investigate the activation of C/EBP Homology Protein (CHOP), the prominent mediator of the endoplasmic reticulum (ER) stress-induced apoptosis under hyperglycemia. We employed streptozotocin- (STZ-) induced diabetic rats to explore the ability of learning and memory by the Morris water maze test. The ultrastructure of hippocampus in diabetic rats and cultured neurons in high glucose medium were observed by transmission electron microscopy and scanning electron microscopy. TUNEL staining was also performed to assess apoptotic cells while the expression of CHOP was assayed by immunohistochemistry and Western blot assay in these hippocampal neurons. Six weeks after diabetes induction, the escape latency increased and the average frequency in finding the platform decreased in diabetic rats (P < 0.05). The morphology of neuron and synaptic structure was impaired; the number of TUNEL-positive cells and the expression of CHOP in hippocampus of diabetic rats and high glucose medium cultured neurons were markedly altered (P < 0.05). The present results suggested that the CHOP-dependent endoplasmic reticulum (ER) stress-mediated apoptosis may be involved in hyperglycemia-induced hippocampal synapses and neurons impairment and promote the diabetic cognitive impairment.

  13. Endoplasmic Reticulum Stress Links Oxidative Stress to Impaired Pancreatic Beta-Cell Function Caused by Human Oxidized LDL

    PubMed Central

    Favre, Dimitri; Ezanno, Hélène; Bonnefond, Amélie; Bonner, Caroline; Gmyr, Valéry; Kerr-Conte, Julie; Gauthier, Benoit R.; Widmann, Christian; Waeber, Gérard; Pattou, François; Froguel, Philippe; Abderrahmani, Amar

    2016-01-01

    Elevated plasma concentration of the pro-atherogenic oxidized low density lipoprotein cholesterol (LDL) triggers adverse effects in pancreatic beta-cells and is associated with type 2 diabetes. Here, we investigated whether the endoplasmic reticulum (ER) stress is a key player coupling oxidative stress to beta-cell dysfunction and death elicited by human oxidized LDL. We found that human oxidized LDL activates ER stress as evidenced by the activation of the inositol requiring 1α, and the elevated expression of both DDIT3 (also called CHOP) and DNAJC3 (also called P58IPK) ER stress markers in isolated human islets and the mouse insulin secreting MIN6 cells. Silencing of Chop and inhibition of ER stress markers by the chemical chaperone phenyl butyric acid (PBA) prevented cell death caused by oxidized LDL. Finally, we found that oxidative stress accounts for activation of ER stress markers induced by oxidized LDL. Induction of Chop/CHOP and p58IPK/P58IPK by oxidized LDL was mimicked by hydrogen peroxide and was blocked by co-treatment with the N-acetylcystein antioxidant. As a conclusion, the harmful effects of oxidized LDL in beta-cells requires ER stress activation in a manner that involves oxidative stress. This mechanism may account for impaired beta-cell function in diabetes and can be reversed by antioxidant treatment. PMID:27636901

  14. The metabolomic signature of Leber's hereditary optic neuropathy reveals endoplasmic reticulum stress.

    PubMed

    Chao de la Barca, Juan Manuel; Simard, Gilles; Amati-Bonneau, Patrizia; Safiedeen, Zainab; Prunier-Mirebeau, Delphine; Chupin, Stéphanie; Gadras, Cédric; Tessier, Lydie; Gueguen, Naïg; Chevrollier, Arnaud; Desquiret-Dumas, Valérie; Ferré, Marc; Bris, Céline; Kouassi Nzoughet, Judith; Bocca, Cinzia; Leruez, Stéphanie; Verny, Christophe; Miléa, Dan; Bonneau, Dominique; Lenaers, Guy; Martinez, M Carmen; Procaccio, Vincent; Reynier, Pascal

    2016-09-15

    the greater expression of C/EBP homologous protein and the increased XBP1 splicing, in fibroblasts from affected patients, all these changes being reversed by the endoplasmic reticulum stress inhibitor, TUDCA (tauroursodeoxycholic acid). Thus, our metabolomic analysis reveals a pharmacologically-reversible endoplasmic reticulum stress in complex I-related Leber's hereditary optic neuropathy fibroblasts, a finding that may open up new therapeutic perspectives for the treatment of Leber's hereditary optic neuropathy with endoplasmic reticulum-targeting drugs.

  15. Endoplasmic reticulum stress, a new wrestler, in the pathogenesis of idiopathic pulmonary fibrosis

    PubMed Central

    Zhang, Lei; Wang, Yi; Pandupuspitasari, Nuruliarizki Shinta; Wu, Guorao; Xiang, Xudong; Gong, Quan; Xiong, Weining; Wang, Cong-Yi; Yang, Ping; Ren, Boxu

    2017-01-01

    Idiopathic pulmonary fibrosis (IPF) has attracted extensive attention for its unexplained progressive lung scarring, short median survival and its unresponsiveness to traditional therapies. Despite extensive studies, the mechanisms underlying IPF pathoetiologies, however, remain poorly understood. Recent advances delineated a potential function of endoplasmic reticulum (ER) stress in meeting the need of fibrotic response, which pinpointed a critical role for the unfolded protein response (UPR) pathways in IPF pathogenesis. In this review, we highlight the effect of ER stress and the activation of UPR on the survival, differentiation, function and proliferation of major profibrotic cells in lung tissues during the course of IPF, and discuss the feasibility whether targeting UPR components could be an orientation for developing effective therapeutic strategies against this devastating disorder in clinical settings. PMID:28337301

  16. Endoplasmic reticulum stress and the unfolded protein response in pancreatic islet inflammation.

    PubMed

    Meyerovich, Kira; Ortis, Fernanda; Allagnat, Florent; Cardozo, Alessandra K

    2016-07-01

    Insulin-secreting pancreatic β-cells are extremely dependent on their endoplasmic reticulum (ER) to cope with the oscillatory requirement of secreted insulin to maintain normoglycemia. Insulin translation and folding rely greatly on the unfolded protein response (UPR), an array of three main signaling pathways designed to maintain ER homeostasis and limit ER stress. However, prolonged or excessive UPR activation triggers alternative molecular pathways that can lead to β-cell dysfunction and apoptosis. An increasing number of studies suggest a role of these pro-apoptotic UPR pathways in the downfall of β-cells observed in diabetic patients. Particularly, the past few years highlighted a cross talk between the UPR and inflammation in the context of both type 1 (T1D) and type 2 diabetes (T2D). In this article, we describe the recent advances in research regarding the interplay between ER stress, the UPR, and inflammation in the context of β-cell apoptosis leading to diabetes.

  17. Flurbiprofen ameliorated obesity by attenuating leptin resistance induced by endoplasmic reticulum stress

    PubMed Central

    Hosoi, Toru; Yamaguchi, Rie; Noji, Kikuko; Matsuo, Suguru; Baba, Sachiko; Toyoda, Keisuke; Suezawa, Takahiro; Kayano, Takaaki; Tanaka, Shinpei; Ozawa, Koichiro

    2014-01-01

    Endoplasmic reticulum (ER) stress, caused by the accumulation of unfolded proteins, is involved in the development of obesity. We demonstrated that flurbiprofen, a nonsteroidal anti-inflammatory drug (NSAID), exhibited chaperone activity, which reduced protein aggregation and alleviated ER stress-induced leptin resistance, characterized by insensitivity to the actions of the anti-obesity hormone leptin. This result was further supported by flurbiprofen attenuating high-fat diet-induced obesity in mice. The other NSAIDs tested did not exhibit such effects, which suggested that this anti-obesity action is mediated independent of NSAIDs. Using ferriteglycidyl methacrylate beads, we identified aldehyde dehydrogenase as the target of flurbiprofen, but not of the other NSAIDs. These results suggest that flurbiprofen may have unique pharmacological properties that reduce the accumulation of unfolded proteins and may represent a new class of drug for the fundamental treatment of obesity. Subject Categories Metabolism; Pharmacology & Drug Discovery PMID:24421337

  18. Mutations in the SPTLC1 protein cause mitochondrial structural abnormalities and endoplasmic reticulum stress in lymphoblasts.

    PubMed

    Myers, Simon J; Malladi, Chandra S; Hyland, Ryan A; Bautista, Tara; Boadle, Ross; Robinson, Phillip J; Nicholson, Garth A

    2014-07-01

    Mutations in serine palmitoyltransferase long chain subunit 1 (SPTLC1) cause the typical length-dependent axonal degeneration hereditary sensory neuropathy type 1 (HSN1). Transmission electron microscopy studies on SPTLC1 mutant lymphoblasts derived from patients revealed specific structural abnormalities of mitochondria. Swollen mitochondria with abnormal cristae were clustered around the nucleus, with some mitochondria being wrapped in rough endoplasmic reticulum (ER) membranes. Total mitochondrial counts revealed a significant change in mitochondrial numbers between healthy and diseased lymphocytes but did not reveal any change in length to width ratios nor were there any changes to cellular function. However, there was a notable change in ER homeostasis, as assessed using key ER stress markers, BiP and ERO1-Lα, displaying reduced protein expression. The observations suggest that SPTLC1 mutations cause mitochondrial abnormalities and ER stress in HSN1 cells.

  19. Crystal structures reveal transient PERK luminal domain tetramerization in endoplasmic reticulum stress signaling.

    PubMed

    Carrara, Marta; Prischi, Filippo; Nowak, Piotr R; Ali, Maruf Mu

    2015-06-03

    Stress caused by accumulation of misfolded proteins within the endoplasmic reticulum (ER) elicits a cellular unfolded protein response (UPR) aimed at maintaining protein-folding capacity. PERK, a key upstream component, recognizes ER stress via its luminal sensor/transducer domain, but the molecular events that lead to UPR activation remain unclear. Here, we describe the crystal structures of mammalian PERK luminal domains captured in dimeric state as well as in a novel tetrameric state. Small angle X-ray scattering analysis (SAXS) supports the existence of both crystal structures also in solution. The salient feature of the tetramer interface, a helix swapped between dimers, implies transient association. Moreover, interface mutations that disrupt tetramer formation in vitro reduce phosphorylation of PERK and its target eIF2α in cells. These results suggest that transient conversion from dimeric to tetrameric state may be a key regulatory step in UPR activation.

  20. alpha-Linolenic acid protects renal cells against palmitic acid lipotoxicity via inhibition of endoplasmic reticulum stress.

    PubMed

    Katsoulieris, Elias; Mabley, Jon G; Samai, Mohamed; Green, Irene C; Chatterjee, Prabal K

    2009-11-25

    Unsaturated fatty acids may counteract the lipotoxicity associated with saturated fatty acids. Palmitic acid induced endoplasmic reticulum (ER) stress and caused apoptotic and necrotic cell death in the renal proximal tubular cell line, NRK-52E. We investigated whether alpha-linolenic acid, an unsaturated fatty acid, protected against ER stress and cell death induced by palmitic acid or by other non-nutrient ER stress generators. Incubation of NRK-52E cells for 24h with palmitic acid produced a significant increase in apoptosis and necrosis. Palmitic acid also increased levels of three indicators of ER stress - the phosphorylated form of the eukaryotic initiation factor 2alpha (eIF2alpha), C/EBP homologous protein (CHOP), and glucose regulated protein 78 (GRP78). alpha-Linolenic acid dramatically reduced cell death and levels of all three indicators of ER stress brought about by palmitic acid. Tunicamycin, which induces ER stress by glycosylation of proteins, produced similar effects to those obtained using palmitic acid; its effects were partially reversed by alpha-linolenic acid. Salubrinal (a phosphatase inhibitor) causes increased levels of the phosphorylated form of eIF2alpha - this effect was partially reversed by alpha-linolenic acid. Palmitoleate, a monosaturated fatty acid, had similar effects to those of alpha-linolenic acid. These results suggest that part of the mechanism of protection of the kidney by unsaturated fatty acids is through inhibition of ER stress, eIF2alpha phosphorylation and consequential reduction of CHOP protein expression and apoptotic renal cell death.

  1. Developmental competence of bovine early embryos depends on the coupled response between oxidative and endoplasmic reticulum stress.

    PubMed

    Yoon, Seung-Bin; Choi, Seon-A; Sim, Bo-Woong; Kim, Ji-Su; Mun, Seong-Eun; Jeong, Pil-Soo; Yang, Hae-Jun; Lee, Youngjeon; Park, Young-Ho; Song, Bong-Seok; Kim, Young-Hyun; Jeong, Kang-Jin; Huh, Jae-Won; Lee, Sang-Rae; Kim, Sun-Uk; Chang, Kyu-Tae

    2014-05-01

    The stress produced by the coupling of reactive oxygen species (ROS) and endoplasmic reticulum (ER) has been explored extensively, but little is known regarding their roles in the early development of mammalian embryos. Here, we demonstrated that the early development of in vitro-produced (IVP) bovine embryos was governed by the cooperative action between ROS and ER stress. Compared with the tension produced by 5% O2, 20% O2 significantly decreased the blastocyst formation rate and cell survival, which was accompanied by increases in ROS and in levels of sXBP-1 transcript, which is an ER stress indicator. In addition, treatment with glutathione (GSH), a ROS scavenger, decreased ROS levels, which resulted in increased blastocyst formation and cell survival rates. Importantly, levels of sXBP-1 and ER stress-associated transcripts were reduced by GSH treatment in developing bovine embryos. Consistent with this observation, tauroursodeoxycholate (TUDCA), an ER stress inhibitor, improved blastocyst developmental rate, trophectoderm proportion, and cell survival. Moreover, ROS and sXBP-1 transcript levels were markedly decreased by supplementation with TUDCA, suggesting a possible mechanism governing the mutual regulation between ROS and ER stress. Interestingly, knockdown of XBP-1 transcripts resulted in both elevation of ROS and decrease of antioxidant transcripts, which ultimately reduced in vitro developmental competence of bovine embryos. Based on these results, in vitro developmental competence of IVP bovine embryos was highly dependent on the coupled response between oxidative and ER stresses. These results increase our understanding of the mechanism(s) governing early embryonic development and may improve strategies for the generation of IVP embryos with high developmental competence.

  2. Renin-angiotensin system activation accelerates atherosclerosis in experimental renal failure by promoting endoplasmic reticulum stress-related inflammation

    PubMed Central

    Yang, Jia; Zhang, Xi; Yu, Xinyi; Tang, Weixue; Gan, Hua

    2017-01-01

    In this study, we investigated the association between the renin-angiotensin system (RAS), endoplasmic reticulum (ER) stress and atherosclerosis (AS) in uremic apolipo-protein E knockout (apoE−/−) mice. Mild uremia was induced by a 5/6 nephrectomy (5/6 Nx) in 10-week-old apoE−/− mice. Four weeks after nephrectomy, the mice received losartan or no treatment for 16 weeks. Sham-operated mice served as the controls. We found that uremia accelerated AS at the aortic root. The activation of ER stress and the significant upregulation of pro-inflammatory cytokines and chemokines were observed in the uremic mice. Phosphorylated inositol-requiring 1α (p-IRE1α), an ER stress marker protein, was mainly expressed in macrophages in the atherosclerotic lesions. Treatment with losartan significantly attenuated aortic AS, inhibited ER stress and reduced aortic inflammation. In in vitro experiments, angiotensin II (Ang II) increased the levels of the common ER stress maker, glucose-regulated protein 78 (GRP78) and the phosphorylation of IRE1α in RAW264.7 macrophages. Treatment with losartan inhibited the activation of ER stress and the upregulation of GRP78, and enhanced the expression of nuclear factor-κB (NF-κB) inhibitor (IκB) in Ang II-stimulated RAW264.7 macrophages. IRE1α-siRNA suppressed inflammation and downregulated IκB expression and IκB kinase (IKK) phosphorylation, which inhibited IκB degradation and NF-κB p65 nuclear translocation in Ang II-treated RAW264.7 macrophages. These findings suggest that RAS activation accelerates AS by promoting ER stress-related inflammation in uremic mice. PMID:28098884

  3. Carfilzomib combined with suberanilohydroxamic acid (SAHA) synergistically promotes endoplasmic reticulum stress in non-small cell lung cancer cell lines

    PubMed Central

    Hanke, Neale T.; Garland, Linda L.; Baker, Amanda F.

    2015-01-01

    Purpose The endoplasmic reticulum (ER) stress response is a therapeutic target for pharmacologic intervention in cancer cells. We hypothesized that combining carfilzomib (CFZ), a proteasome inhibitor, and vorinostat (SAHA), a histone deacetylase (HDAC) inhibitor, would synergistically activate ER stress in non-small cell lung cancer (NSCLC) cell lines resulting in enhanced anti-tumor activity. Methods Five NSCLC cell lines were treated with CFZ, SAHA, or the combination and cell proliferation measured using the MTT assay. Calcusyn software was utilized to determine the combination index as a measure of synergy. Cell viability and cytotoxicity were measured using trypan blue exclusion, CellTiter and CytoTox assays. Western blot was used to measure markers of apoptosis, ER stress, and oxidative stress related proteins. Reactive oxygen species (ROS) was measured using the fluorophore CM-H2DCFDA. Results Synergistic activity was observed for all cell lines following 48 and 72 hours of combined treatment. H520 and A549 cell lines were used to assess viability and apoptosis. In both cell lines, increased death and cleaved caspase-3 was observed following combination treatment as compared with single agent treatments. Combination therapy was associated with upregulation of ER stress regulated proteins including activating transcription factor 4, GRP78/BiP, and C/EBP homologous protein. Both cell lines also showed increased ROS and the oxidative stress-related protein, heat shock protein 70. Conclusion Combining proteasome inhibition with HDAC inhibition enhances ER stress which may contribute to the synergistic anti-cancer activity observed in NSCLC cell lines. Further pre-clinical and clinical studies of CFZ + SAHA in NSCLC are warranted. PMID:26385374

  4. Zonisamide suppresses endoplasmic reticulum stress-induced neuronal cell damage in vitro and in vivo.

    PubMed

    Tsujii, Saori; Ishisaka, Mitsue; Shimazawa, Masamitsu; Hashizume, Takanori; Hara, Hideaki

    2015-01-05

    Zonisamide has been reported to have protective effects on epilepsy and Parkinson׳s disease and to work via various mechanisms of action, such as inhibition of monoamine oxidase-B and enhancement of tyrosine hydroxylase. Recently, it has been suggested that zonisamide itself shows neuroprotective actions. Therefore, in the present study we investigated the neuroprotective effects of zonisamide against endoplasmic reticulum (ER) stress. We used human neuroblastoma (SH-SY5Y) cells and investigated the protective effects of zonisamide against tunicamycin- and thapsigargin-induced neuronal cell death. In addition, we investigated the effect of zonisamide against 1-methyl-4-phenylpyridinium (MPP⁺)-induced cell death and the mechanism of protection against ER stress. In vivo, we investigated the effect of zonisamide (20 mg/kg, p.o.) in the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced mouse model of Parkinson׳s disease. Zonisamide not only suppressed MPP⁺-induced cell death, but also inhibited ER stress-induced cell death and suppressed the expression of ER stress-related factors such as C/EBO homologous protein (CHOP) in vivo. Furthermore, zonisamide inhibited the activation of caspase-3 in vitro. These results suggest that zonisamide affected ER stress via caspase-3. We think that ER stress, particularly the mechanism via caspase-3, is involved in part of the neuroprotective effect of zonisamide against the experimental models of Parkinson׳s disease.

  5. Endoplasmic Reticulum Stress and Ca2+ Depletion Differentially Modulate the Sterol Regulatory Protein PCSK9 to Control Lipid Metabolism.

    PubMed

    Lebeau, Paul; Al-Hashimi, Ali; Sood, Sudesh; Lhoták, Šárka; Yu, Pei; Gyulay, Gabriel; Paré, Guillaume; Chen, S R Wayne; Trigatti, Bernardo; Prat, Annik; Seidah, Nabil G; Austin, Richard C

    2017-01-27

    Accumulating evidence implicates endoplasmic reticulum (ER) stress as a mediator of impaired lipid metabolism, thereby contributing to fatty liver disease and atherosclerosis. Previous studies demonstrated that ER stress can activate the sterol regulatory element-binding protein-2 (SREBP2), an ER-localized transcription factor that directly up-regulates sterol regulatory genes, including PCSK9 Given that PCSK9 contributes to atherosclerosis by targeting low density lipoprotein (LDL) receptor (LDLR) degradation, this study investigates a novel mechanism by which ER stress plays a role in lipid metabolism by examining its ability to modulate PCSK9 expression. Herein, we demonstrate the existence of two independent effects of ER stress on PCSK9 expression and secretion. In cultured HuH7 and HepG2 cells, agents or conditions that cause ER Ca(2+) depletion, including thapsigargin, induced SREBP2-dependent up-regulation of PCSK9 expression. In contrast, a significant reduction in the secreted form of PCSK9 protein was observed in the media from both thapsigargin- and tunicamycin (TM)-treated HuH7 cells, mouse primary hepatocytes, and in the plasma of TM-treated C57BL/6 mice. Furthermore, TM significantly increased hepatic LDLR expression and reduced plasma LDL concentrations in mice. Based on these findings, we propose a model in which ER Ca(2+) depletion promotes the activation of SREBP2 and subsequent transcription of PCSK9. However, conditions that cause ER stress regardless of their ability to dysregulate ER Ca(2+) inhibit PCSK9 secretion, thereby reducing PCSK9-mediated LDLR degradation and promoting LDLR-dependent hepatic cholesterol uptake. Taken together, our studies provide evidence that the retention of PCSK9 in the ER may serve as a potential strategy for lowering LDL cholesterol levels.

  6. Myricetin induces apoptosis via endoplasmic reticulum stress and DNA double-strand breaks in human ovarian cancer cells

    PubMed Central

    XU, YE; XIE, QI; WU, SHAOHUA; YI, DAN; YU, YANG; LIU, SHIBING; LI, SONGYAN; LI, ZHIXIN

    2016-01-01

    The mechanisms underlying myricetin-induced cancer cell apoptosis remain to be elucidated. Certain previous studies have shown that myricetin induces apoptosis through the mitochondrial pathway. Apoptosis, however, can also be induced by other classical pathways, including endoplasmic reticulum (ER) stress and DNA double-strand breaks (DSBs). The aim of the present study was to assess whether these two apoptotic pathways are involved in myricetin-induced cell death in SKOV3 ovarian cancer cells. The results revealed that treatment with myricetin inhibited viability of SKOV3 cells in a dose-dependent manner. Myricetin induced nuclear chromatin condensation and fragmentation, and also upregulated the protein levels of active caspase 3 in a time-dependent manner. In addition, myricetin upregulated ER stress-associated proteins, glucose-regulated protein-78 and C/EBP homologous protein in SKOV3 cells. Phosphorylation of H2AX, a marker of DNA DSBs, was revealed to be upregulated in myricetin-treated cells. The data indicated that myricetin induces DNA DSBs and ER stress, which leads to apoptosis in SKOV3 cells. PMID:26782830

  7. Chemical chaperon 4-phenylbutyrate protects against the endoplasmic reticulum stress-mediated renal fibrosis in vivo and in vitro.

    PubMed

    Liu, Shing-Hwa; Yang, Ching-Chin; Chan, Ding-Cheng; Wu, Cheng-Tien; Chen, Li-Ping; Huang, Jenq-Wen; Hung, Kuan-Yu; Chiang, Chih-Kang

    2016-04-19

    Renal tubulointerstitial fibrosis is the common and final pathologic change of kidney in end-stage renal disease. Interesting, endoplasmic reticulum (ER) stress is known to contribute to the pathophysiological mechanisms during the development of renal fibrosis. Here, we investigated the effects of chemical chaperon sodium 4-phenylbutyrate (4-PBA) on renal fibrosis in vivo and in vitro. In a rat unilateral ureteral obstruction (UUO) model, 4-PBA mimicked endogenous ER chaperon in the kidneys and significantly reduced glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), activating transcription factor 4 (ATF4), and phosphorylated JNK protein expressions as well as restored spliced X-box-binding protein 1 (XBP1) expressions in the kidneys of UUO rats. 4-PBA also attenuated the increases of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) protein expressions, tubulointerstitial fibrosis, and apoptosis in the kidneys of UUO rats. Moreover, transforming growth factor (TGF)-β markedly increased ER stress-associated molecules, profibrotic factors, and apoptotic markers in the renal tubular cells (NRK-52E), all of which could be significantly counteracted by 4-PBA treatment. 4-PBA also diminished TGF-β-increased CTGF promoter activity and CTGF mRNA expression in NRK-52E cells. Taken together, our results indicated that 4-PBA acts as an ER chaperone to ameliorate ER stress-induced renal tubular cell apoptosis and renal fibrosis.

  8. 3-O-Hydroxytyrosol glucuronide and 4-O-hydroxytyrosol glucuronide reduce endoplasmic reticulum stress in vitro.

    PubMed

    Giordano, Elena; Dangles, Olivier; Rakotomanomana, Njara; Baracchini, Silvia; Visioli, Francesco

    2015-10-01

    Endoplasmic reticulum (ER) stress is important for atherosclerosis development and is mediated by the unfolded protein response (UPR). In this work, we synthesized two among the most physiologically-prominent hydroxytyrosol HT hepatic metabolites, i.e. 3-O-HT glucuronide and 4-O-HT glucuronide and we tested their activities on ER stress (in human hepatocarcinoma HepG2 cells), to gain further insight into the cardiopreventive properties of HT, extra virgin olive oil, and the Mediterranean diet. We report that 3-O-HT glucuronide and 4-O-HT glucuronide inhibit tunicamycin-induced ER stress. As compared with the effects of the parent molecule, 3-O-HT glucuronide and 4-O-HT glucuronide at 10 μM and 25 μM alone induced a milder change in mRNA expression levels of both CCAAT-enhancer-binding protein homologous protein (CHOP) and glucose regulated protein GRP78 immunoglobulin heavy chain binding protein (BiP). In conclusion, we add further evidence to the hypothesis that the HT intake might be atheroprotective and reiterate the usefulness to preferably use high-quality, high-(poly)phenol extra virgin olive oil as a prominent condiment.

  9. Chemical chaperon 4-phenylbutyrate protects against the endoplasmic reticulum stress-mediated renal fibrosis in vivo and in vitro

    PubMed Central

    Wu, Cheng-Tien; Chen, Li-Ping; Huang, Jenq-Wen; Hung, Kuan-Yu; Chiang, Chih-Kang

    2016-01-01

    Renal tubulointerstitial fibrosis is the common and final pathologic change of kidney in end-stage renal disease. Interesting, endoplasmic reticulum (ER) stress is known to contribute to the pathophysiological mechanisms during the development of renal fibrosis. Here, we investigated the effects of chemical chaperon sodium 4-phenylbutyrate (4-PBA) on renal fibrosis in vivo and in vitro. In a rat unilateral ureteral obstruction (UUO) model, 4-PBA mimicked endogenous ER chaperon in the kidneys and significantly reduced glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), activating transcription factor 4 (ATF4), and phosphorylated JNK protein expressions as well as restored spliced X-box-binding protein 1 (XBP1) expressions in the kidneys of UUO rats. 4-PBA also attenuated the increases of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) protein expressions, tubulointerstitial fibrosis, and apoptosis in the kidneys of UUO rats. Moreover, transforming growth factor (TGF)-β markedly increased ER stress-associated molecules, profibrotic factors, and apoptotic markers in the renal tubular cells (NRK-52E), all of which could be significantly counteracted by 4-PBA treatment. 4-PBA also diminished TGF-β-increased CTGF promoter activity and CTGF mRNA expression in NRK-52E cells. Taken together, our results indicated that 4-PBA acts as an ER chaperone to ameliorate ER stress-induced renal tubular cell apoptosis and renal fibrosis. PMID:26959118

  10. Overexpression of TCL1 activates the endoplasmic reticulum stress response: a novel mechanism of leukemic progression in mice

    PubMed Central

    Kriss, Crystina L.; Pinilla-Ibarz, Javier A.; Mailloux, Adam W.; Powers, John J.; Tang, Chih-Hang Anthony; Kang, Chang Won; Zanesi, Nicola; Epling-Burnette, Pearlie K.; Sotomayor, Eduardo M.; Croce, Carlo M.

    2012-01-01

    Chronic lymphocytic leukemia (CLL) represents 30% of adult leukemia. TCL1 is expressed in ∼ 90% of human CLL. Transgenic expression of TCL1 in murine B cells (Eμ-TCL1) results in mouse CLL. Here we show for the first time that the previously unexplored endoplasmic reticulum (ER) stress response is aberrantly activated in Eμ-TCL1 mouse and human CLL. This includes activation of the IRE-1/XBP-1 pathway and the transcriptionally up-regulated expression of Derlin-1, Derlin-2, BiP, GRP94, and PDI. TCL1 associates with the XBP-1 transcription factor, and causes the dysregulated expression of the transcription factors, Pax5, IRF4, and Blimp-1, and of the activation-induced cytidine deaminase. In addition, TCL1-overexpressing CLL cells manufacture a distinctly different BCR, as we detected increased expression of membrane-bound IgM and altered N-linked glycosylation of Igα and Igβ, which account for the hyperactive BCR in malignant CLL. To demonstrate that the ER stress-response pathway is a novel molecular target for the treatment of CLL, we blocked the IRE-1/XBP-1 pathway using a novel inhibitor, and observed apoptosis and significantly stalled growth of CLL cells in vitro and in mice. These studies reveal an important role of TCL1 in activating the ER stress response in support for malignant progression of CLL. PMID:22692508

  11. Endoplasmic reticulum stress mediates sulforaphane-induced apoptosis of HepG2 human hepatocellular carcinoma cells.

    PubMed

    Zou, Xiang; Qu, Zhongyuan; Fang, Yueni; Shi, Xin; Ji, Yubin

    2017-01-01

    Sulforaphane (SFN) is a naturally occurring chemopreventive agent, which effectively inhibits proliferation of HepG2 human hepatocellular carcinoma cells via mitochondria‑mediated apoptosis. Endoplasmic reticulum stress is considered the most important cause of cell apoptosis; therefore, the present study aimed to determine whether the endoplasmic reticulum pathway was involved in SFN-induced apoptosis of HepG2 cells. An MTT assay was used to detect the inhibitory effects of SFN on HepG2 cells. Fluorescence microscopy was used to observe the morphological changes in apoptotic cells, and western blot analysis was conducted to detect the expression of binding immunoglobulin protein (Bip)/glucose-regulated protein 78 (GRP78), X‑box binding protein‑1 (XBP‑1) and BH3 interacting domain death agonist (Bid). Furthermore, flow cytometry was used to determine the apoptotic rate of HepG2 cells, and the protein expression of C/EBP homologous protein (CHOP)/growth arrest‑ and DNA damage‑inducible gene 153 (GADD153) and caspase-12 in HepG2 cells. The results indicated that SFN significantly inhibited the proliferation of HepG2 cells; the half maximal inhibitory concentration values were 32.03±0.96, 20.90±1.96 and 13.87±0.44 µmol/l, following treatment with SFN for 24, 48 and 72 h, respectively. Following 48 h of SFN treatment (10, 20 and 40 µmol/l), the apoptotic rates of HepG2 cells were 31.8, 61.3 and 77.1%, respectively. Furthermore, after 48 h of exposure to SFN, the cells presented typical morphological alterations of apoptosis, as detected under fluorescence microscopy. Treatment with SFN for 48 h also significantly upregulated the protein expression levels of Bip/GRP78, XBP‑1, caspase‑12, CHOP/GADD153 and Bid in HepG2 cells. In conclusion, endoplasmic reticulum stress may be considered the most important mechanism underlying SFN-induced apoptosis in HepG2 cells.

  12. Protective effect of catechin in type I Gaucher disease cells by reducing endoplasmic reticulum stress

    SciTech Connect

    Lee, Yea-Jin; Kim, Sung-Jo; Heo, Tae-Hwe

    2011-09-23

    Highlights: {yields} Catechin reduces the expression level of ER stress marker protein in type I Gaucher disease cells. {yields} Catechin induces the proliferation rate of GD cells similar levels to normal cells. {yields} Catechin improves wound healing activity. {yields} Catechin-mediated reductions in ER stress may be associated with enhanced cell survival. {yields} We identified catechin as a protective agent against ER stress in GD cells. -- Abstract: Gaucher disease (GD) is the most common lysosomal storage disorder (LSD) and is divided into three phenotypes, I, II, and III. Type I is the most prevalent form and has its onset in adulthood. The degree of endoplasmic reticulum (ER) stress is one of the factors that determine GD severity. It has recently been reported that antioxidants reduce ER stress and apoptosis by scavenging the oxidants that cause oxidative stress. For this report, we investigated the possibility that catechin can act on type I GD patient cells to alleviate the pathogenic conditions of GD. We treated GD cells with catechin and examined the expression level of GRP78/BiP (an ER stress marker) by western blots and fluorescence microscopy, the proliferation rate of GD cells, and scratch-induced wound healing activity. Our results show that catechin reduces the expression level of GRP78/BiP, leads to cell proliferation rates of GD cells similar levels to normal cells, and improves wound healing activity. We conclude that catechin protects against ER stress in GD cells and catechin-mediated reductions in ER stress may be associated with enhanced cell survival.

  13. Asbestos-induced disruption of calcium homeostasis induces endoplasmic reticulum stress in macrophages.

    PubMed

    Ryan, Alan J; Larson-Casey, Jennifer L; He, Chao; Murthy, Shuhba; Carter, A Brent

    2014-11-28

    Although the mechanisms for fibrosis development remain largely unknown, recent evidence indicates that endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) may act as an important fibrotic stimulus in diseased lungs. ER stress is observed in lungs of patients with idiopathic pulmonary fibrosis. In this study we evaluated if ER stress and the UPR was present in macrophages exposed to chrysotile asbestos and if ER stress in macrophages was associated with asbestos-induced pulmonary fibrosis. Macrophages exposed to chrysotile had elevated transcript levels of several ER stress genes. Macrophages loaded with the Ca(2+)-sensitive dye Fura2-AM showed that cytosolic Ca(2+) increased significantly within minutes after chrysotile exposure and remained elevated for a prolonged time. Chrysotile-induced increases in cytosolic Ca(2+) were partially inhibited by either anisomycin, an inhibitor of passive Ca(2+) leak from the ER, or 1,2-bis(2-aminophenoxyl)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM), an intracellular Ca(2+) chelator known to deplete ER Ca(2+) stores. Anisomycin inhibited X-box-binding protein 1 (XBP1) mRNA splicing and reduced immunoglobulin-binding protein (BiP) levels, whereas BAPTA-AM increased XBP1 splicing and BiP expression, suggesting that ER calcium depletion may be one factor contributing to ER stress in cells exposed to chrysotile. To evaluate ER stress in vivo, asbestos-exposed mice showed fibrosis development, and alveolar macrophages from fibrotic mice showed increased expression of BiP. Bronchoalveolar macrophages from asbestosis patients showed increased expression of several ER stress genes compared with normal subjects. These findings suggest that alveolar macrophages undergo ER stress, which is associated with fibrosis development.

  14. Titanium Dioxide Nanoparticles Induce Endoplasmic Reticulum Stress-Mediated Autophagic Cell Death via Mitochondria-Associated Endoplasmic Reticulum Membrane Disruption in Normal Lung Cells.

    PubMed

    Yu, Kyeong-Nam; Chang, Seung-Hee; Park, Soo Jin; Lim, Joohyun; Lee, Jinkyu; Yoon, Tae-Jong; Kim, Jun-Sung; Cho, Myung-Haing

    2015-01-01

    Nanomaterials are used in diverse fields including food, cosmetic, and medical industries. Titanium dioxide nanoparticles (TiO2-NP) are widely used, but their effects on biological systems and mechanism of toxicity have not been elucidated fully. Here, we report the toxicological mechanism of TiO2-NP in cell organelles. Human bronchial epithelial cells (16HBE14o-) were exposed to 50 and 100 μg/mL TiO2-NP for 24 and 48 h. Our results showed that TiO2-NP induced endoplasmic reticulum (ER) stress in the cells and disrupted the mitochondria-associated endoplasmic reticulum membranes (MAMs) and calcium ion balance, thereby increasing autophagy. In contrast, an inhibitor of ER stress, tauroursodeoxycholic acid (TUDCA), mitigated the cellular toxic response, suggesting that TiO2-NP promoted toxicity via ER stress. This novel mechanism of TiO2-NP toxicity in human bronchial epithelial cells suggests that further exhaustive research on the harmful effects of these nanoparticles in relevant organisms is needed for their safe application.

  15. Endoplasmic reticulum stress inhibition attenuates hypertensive chronic kidney disease through reduction in proteinuria

    PubMed Central

    Mohammed-Ali, Zahraa; Lu, Chao; Marway, Mandeep K.; Carlisle, Rachel E.; Ask, Kjetil; Lukic, Dusan; Krepinsky, Joan C.; Dickhout, Jeffrey G.

    2017-01-01

    Endoplasmic reticulum (ER) stress is implicated in chronic kidney disease (CKD) development in patients and in animal models. Here we show that ER stress inhibition through 4-phenylbutyric acid (4-PBA) administration decreases blood pressure, albuminuria, and tubular casts in an angiotensin II/deoxycorticosterone acetate/salt murine model of CKD. Lower albuminuria in 4-PBA-treated mice was associated with higher levels of cubilin protein in renal tissue membrane fractions. 4-PBA decreased renal interstitial fibrosis, renal CD3+ T-cell and macrophage infiltration, mRNA expression of TGFβ1, Wnt signaling molecules, and ER stress-induced pro-inflammatory genes. CHOP deficient mice that underwent this model of CKD developed hypertension comparable to wild type mice, but had less albuminuria and tubular casts. CHOP deficiency resulted in higher nephrin levels and decreased glomerulosclerosis compared to wild type mice; this effect was accompanied by lower macrophage infiltration and fibrosis. Our findings portray ER stress inhibition as a means to alleviate hypertensive CKD by preserving glomerular barrier integrity and tubular function. These results demonstrate ER stress modulation as a novel target for preserving renal function in hypertensive CKD. PMID:28148966

  16. Sulfur mustard induces an endoplasmic reticulum stress response in the mouse ear vesicant model

    PubMed Central

    Chang, Yoke-Chen; Wang, James D.; Svoboda, Kathy K.; Casillas, Robert P.; Laskin, Jeffrey D.; Gordon, Marion K.; Gerecke, Donald R.

    2013-01-01

    The endoplasmic reticulum (ER) stress response is a cell survival pathway upregulated when cells are under severe stress. Severely damaged mouse ear skin exposed to the vesicant, sulfur mustard (bis-2-chloroethyl sulfide, SM), resulted in increased expression of ER chaperone proteins that accompany misfolded and incorrectly made proteins targeted for degradation. Time course studies with SM using the mouse ear vesicant model (MEVM) showed progressive histopathologic changes including edema, separation of the epidermis from the dermis, persistent inflammation, upregulation of laminin γ2 (one of the chains of laminin-332, a heterotrimeric skin glycoprotein required for wound repair), and delayed wound healing from 24 h to 168 h post exposure. This was associated with time related increased expression of the cell survival ER stress marker, GRP78/BiP, and the ER stress apoptosis marker, GADD153/CHOP, suggesting simultaneous activation of both cell survival and non-mitochondrial apoptosis pathways. Dual immunofluorescence labeling of a keratinocyte migration promoting protein, laminin γ2 and GRP78/BIP, showed colocalization of the two molecules 72 h post exposure indicating that the laminin γ2 was misfolded after SM exposure and trapped within the ER. Taken together, these data show that ER stress is induced in mouse skin within 24 h of vesicant exposure in a defensive response to promote cell survival; however, it appears that this response is rapidly overwhelmed by the apoptotic pathway as a consequence of severe SM-induced injury. PMID:23357548

  17. Tribbles 3 Mediates Endoplasmic Reticulum Stress-Induced Insulin Resistance in Skeletal Muscle

    PubMed Central

    Koh, Ho-Jin; Toyoda, Taro; Didesch, Michelle M.; Lee, Min-Young; Sleeman, Mark W.; Kulkarni, Rohit N.; Musi, Nicolas; Hirshman, Michael F.; Goodyear, Laurie J.

    2013-01-01

    Endoplasmic Reticulum (ER) stress has been linked to insulin resistance in multiple tissues but the role of ER stress in skeletal muscle has not been explored. ER stress has also been reported to increase tribbles 3 (TRB3) expression in multiple cell lines. Here, we report that high fat feeding in mice, and obesity and type 2 diabetes in humans significantly increases TRB3 and ER stress markers in skeletal muscle. Overexpression of TRB3 in C2C12 myotubes and mouse tibialis anterior muscles significantly impairs insulin signaling. Incubation of C2C12 cells and mouse skeletal muscle with ER stressors thapsigargin and tunicamycin increases TRB3 and impairs insulin signaling and glucose uptake, effects reversed in cells overexpressing RNAi for TRB3 and in muscles from TRB3 knockout mice. Furthermore, TRB3 knockout mice are protected from high fat diet-induced insulin resistance in skeletal muscle. These data demonstrate that TRB3 mediates ER stress-induced insulin resistance in skeletal muscle. PMID:23695665

  18. Cannabidiol protects oligodendrocyte progenitor cells from inflammation-induced apoptosis by attenuating endoplasmic reticulum stress.

    PubMed

    Mecha, M; Torrao, A S; Mestre, L; Carrillo-Salinas, F J; Mechoulam, R; Guaza, C

    2012-06-28

    Cannabidiol (CBD) is the most abundant cannabinoid in Cannabis sativa that has no psychoactive properties. CBD has been approved to treat inflammation, pain and spasticity associated with multiple sclerosis (MS), of which demyelination and oligodendrocyte loss are hallmarks. Thus, we investigated the protective effects of CBD against the damage to oligodendrocyte progenitor cells (OPCs) mediated by the immune system. Doses of 1 μM CBD protect OPCs from oxidative stress by decreasing the production of reactive oxygen species. CBD also protects OPCs from apoptosis induced by LPS/IFNγ through the decrease of caspase 3 induction via mechanisms that do not involve CB1, CB2, TRPV1 or PPARγ receptors. Tunicamycin-induced OPC death was attenuated by CBD, suggesting a role of endoplasmic reticulum (ER) stress in the mode of action of CBD. This protection against ER stress-induced apoptosis was associated with reduced phosphorylation of eiF2α, one of the initiators of the ER stress pathway. Indeed, CBD diminished the phosphorylation of PKR and eiF2α induced by LPS/IFNγ. The pro-survival effects of CBD in OPCs were accompanied by decreases in the expression of ER apoptotic effectors (CHOP, Bax and caspase 12), and increased expression of the anti-apoptotic Bcl-2. These findings suggest that attenuation of the ER stress pathway is involved in the 'oligoprotective' effects of CBD during inflammation.

  19. Cannabidiol protects oligodendrocyte progenitor cells from inflammation-induced apoptosis by attenuating endoplasmic reticulum stress

    PubMed Central

    Mecha, M; Torrao, A S; Mestre, L; Carrillo-Salinas, F J; Mechoulam, R; Guaza, C

    2012-01-01

    Cannabidiol (CBD) is the most abundant cannabinoid in Cannabis sativa that has no psychoactive properties. CBD has been approved to treat inflammation, pain and spasticity associated with multiple sclerosis (MS), of which demyelination and oligodendrocyte loss are hallmarks. Thus, we investigated the protective effects of CBD against the damage to oligodendrocyte progenitor cells (OPCs) mediated by the immune system. Doses of 1 μM CBD protect OPCs from oxidative stress by decreasing the production of reactive oxygen species. CBD also protects OPCs from apoptosis induced by LPS/IFNγ through the decrease of caspase 3 induction via mechanisms that do not involve CB1, CB2, TRPV1 or PPARγ receptors. Tunicamycin-induced OPC death was attenuated by CBD, suggesting a role of endoplasmic reticulum (ER) stress in the mode of action of CBD. This protection against ER stress-induced apoptosis was associated with reduced phosphorylation of eiF2α, one of the initiators of the ER stress pathway. Indeed, CBD diminished the phosphorylation of PKR and eiF2α induced by LPS/IFNγ. The pro-survival effects of CBD in OPCs were accompanied by decreases in the expression of ER apoptotic effectors (CHOP, Bax and caspase 12), and increased expression of the anti-apoptotic Bcl-2. These findings suggest that attenuation of the ER stress pathway is involved in the ‘oligoprotective' effects of CBD during inflammation. PMID:22739983

  20. Acid Sphingomyelinase Mediates Oxidized-LDL Induced Apoptosis in Macrophage via Endoplasmic Reticulum Stress

    PubMed Central

    Zhao, Min; Pan, Wei; Shi, Rui-zheng; Bai, Yong-ping; You, Bo-yang; Zhang, Kai; Fu, Qiong-mei; Schuchman, Edward H.

    2016-01-01

    Aim: Macrophage apoptosis is a vital event in advanced atherosclerosis, and oxidized low-density lipoprotein (ox-LDL) is a major contributor to this process. Acid sphingomyelinase (ASM) and ceramide are also involved in the induction of apoptosis, particularly in macrophages. Our current study focuses on ASM and investigates its role in ox-LDL-induced macrophage apoptosis. Methods: Human THP-1 and mouse peritoneal macrophages were cultured in vitro and treated with ox-LDL. ASM activity and ceramide levels were quantified using ultra performance liquid chromatography. Protein and mRNA levels were analyzed using Western blot analysis and quantitative realtime PCR, respectively. Cell apoptosis was determined using Hoechst staining and flow cytometry. Results: Ox-LDL-induced macrophage apoptosis was triggered by profound endoplasmic reticulum (ER) stress, leading to an upregulation of ASM activity and ceramide levels at an early stage. ASM was inhibited by siRNA or desipramine (DES), and/or ceramide was degraded by recombinant acid ceramidase (AC). These events attenuated the effect of ox-LDL on ER stress. In contrast, recombinant ASM upregulated ceramide and ER stress. ASM siRNA, DES, recombinant AC, and ER stress inhibitor 4-phenylbutyric acid were blocked by elevated levels of C/EBP homologous protein (CHOP); ox-LDL induced elevated levels of CHOP. These events attenuated macrophage apoptosis. Conclusion: These results indicate that ASM/ceramide signaling pathway is involved in ox-LDL-induced macrophage apoptosis via ER stress pathway. PMID:26923251

  1. IGL-1 solution reduces endoplasmic reticulum stress and apoptosis in rat liver transplantation

    PubMed Central

    Mosbah, I B; Zaouali, M A; Martel, C; Bjaoui, M; Abdennebi, H B; Hotter, G; Brenner, C; Roselló-Catafau, J

    2012-01-01

    Injury due to cold ischemia reperfusion (I/R) is a major cause of primary graft non-function following liver transplantation. We postulated that I/R-induced cellular damage during liver transplantation might affect the secretory pathway, particularly at the endoplasmic reticulum (ER). We examined the involvement of ER stress in organ preservation, and compared cold storage in University of Wisconsin (UW) solution and in Institute Georges Lopez-1 (IGL-1) solution. In one group of rats, livers were preserved in UW solution for 8 h at 4 °C, and then orthotopic liver transplantation was performed according to Kamada's cuff technique. In another group, livers were preserved in IGL-1 solution. The effect of each preservation solution on the induction of ER stress, hepatic injury, mitochondrial damage and cell death was evaluated. As expected, we found increased ER stress after liver transplantation. IGL-1 solution significantly attenuated ER damage by reducing the activation of three pathways of unfolded protein response and their effector molecules caspase-12, C/EBP homologous protein-10, X-box-binding protein 1, tumor necrosis factor-associated factor 2 and eukaryotic translation initiation factor 2. This attenuation of ER stress was associated with a reduction in hepatic injury and cell death. Our results show that IGL-1 solution may be a useful means to circumvent excessive ER stress reactions associated with liver transplantation, and may optimize graft quality. PMID:22402603

  2. Evidence that endoplasmic reticulum (ER) stress and caspase-4 activation occur in human neutrophils.

    PubMed

    Binet, François; Chiasson, Sonia; Girard, Denis

    2010-01-01

    Apoptosis can result from activation of three major pathways: the extrinsic, the intrinsic, and the most recently identified endoplasmic reticulum (ER) stress-mediated pathway. While the two former pathways are known to be operational in human polymorphonuclear neutrophils (PMNs), the existence of the ER stress-mediated pathway, generally involving caspase-4, has never been reported in these cells. Recently, we have documented that arsenic trioxide (ATO) induced apoptosis in human PMNs by a mechanism that needs to be further investigated. In this study, using immunofluorescence and electron microscopy, we present evidence of ER alterations in PMNs activated by the ER stress inducer arsenic trioxide (ATO). Several key players of the unfolded protein response, including GRP78, GADD153, ATF6, XBP1 and eIF2alpha are expressed and activated in PMNs treated with ATO or other ER stress inducers. Although caspase-4 is expressed and activated in neutrophils, treatment with a caspase-4 inhibitor did not attenuate the pro-apoptotic effect of ATO at a concentration that reverses caspase-4 processing and activation. Our results demonstrate for the first time that the ER stress-mediated apoptotic pathway operates in human neutrophils.

  3. Tunicamycin-induced Endoplasmic Reticulum Stress Upregulates the Expression of Pentraxin 3 in Human Retinal Pigment Epithelial Cells

    PubMed Central

    Hwang, Narae; Kwon, Min-Young; Cha, Jae Bong; Chung, Su Wol

    2016-01-01

    Purpose To investigate the production of long pentraxin 3 (PTX3) in response to tunicamycin-induced endoplasmic reticulum (ER) stress and its role in ER stress-associated cell death, PTX3 expression was evaluated in the human retinal pigment epithelial cell line, ARPE-19. Methods PTX3 production in ARPE-19 cells was analyzed in the absence or presence of tunicamycin treatment by enzyme-linked immunosorbent assay. PTX3 protein and mRNA levels were estimated using western blot analysis and real-time reverse transcription-polymerase chain reaction, respectively. Protein and mRNA levels of CCAAT-enhancer-binding protein homologous protein (CHOP) and ARPE-19 cell viability were measured in the presence of tunicamycin-induced ER stress in control or PTX3 small hairpin RNA (shRNA)-transfected ARPE-19 cells. Results The protein and mRNA levels of PTX3 were found to be significantly increased by tunicamycin treatment. PTX3 production was significantly decreased in inositol-requiring enzyme 1α shRNA-transfected ARPE-19 cells compared to control shRNA-transfected cells. Furthermore, pretreatment with the NF-κB inhibitor abolished tunicamycin-induced PTX3 production. Decreased cell viability and prolonged protein and mRNA expression of CHOP were observed under tunicamycin-induced ER stress in PTX3 shRNA transfected ARPE-19 cells. Conclusions These results suggest that PTX3 production increased in the presence of tunicamycin-induced ER stress. Therefore, PTX3 could be an important protector of ER stress-induced cell death in human retinal pigment epithelial cells. Inositol-requiring enzyme 1α and the NF-κB signaling pathway may serve as potential targets for regulation of PTX3 expression in the retina. Therefore, their role in PTX3 expression needs to be further investigated. PMID:27980366

  4. Endoplasmic reticulum stress plays critical role in brain damage after chronic intermittent hypoxia in growing rats.

    PubMed

    Cai, Xiao-Hong; Li, Xiu-Cui; Jin, Sheng-Wei; Liang, Dong-Shi; Wen, Zheng-Wang; Cao, Hong-Chao; Mei, Hong-Fang; Wu, Ying; Lin, Zhong-Dong; Wang, Liang-Xing

    2014-07-01

    Obstructive sleep apnea hypopnea syndrome (OSAHS) in children is associated with multiple system morbidities. Cognitive dysfunction as a result of central nervous system complication has been reported in children with OSAHS. However, the underlying mechanisms are poorly understood. Endoplasmic reticulum stress (ERS)-related apoptosis plays an important role in various diseases of the central nervous system, but very little is known about the role of ERS in mediating pathophysiological reactions to cognitive dysfunction in OSAHS. Chronic intermittent hypoxia (CIH) exposures, modeling OSAHS, across 2 and 4weeks in growing rats made more reference memory errors, working memory errors and total memory errors in the 8-Arm radial maze task, increased significantly TUNEL positive cells, upregulated the unfolded protein response in the hippocampus and prefrontal cortex as evidenced by increased phosphorylation of PKR-like endoplasmic reticulum kinase, inositol-requiring enzyme l and some downstream products. A selective inhibitor of eukaryotic initiation factor-2a dephosphorylation, salubrinal, prevented C/EBP-homologous protein activation in the hippocampus and prefrontal cortex throughout hypoxia/reoxygenation exposure. Our findings suggest that ERS mediated cell apoptosis may be one of the underlying mechanisms of cognitive dysfunction in OSAHS children. Further, a specific ERS inhibitor Salubrinal should be tested for neuroprotection against CIH-induced injury.

  5. Endoplasmic reticulum calcium release potentiates the ER stress and cell death caused by an oxidative stress in MCF-7 cells.

    PubMed

    Dejeans, Nicolas; Tajeddine, Nicolas; Beck, Raphaël; Verrax, Julien; Taper, Henryk; Gailly, Philippe; Calderon, Pedro Buc

    2010-05-01

    Increase in cytosolic calcium concentration ([Ca2+](c)), release of endoplasmic reticulum (ER) calcium ([Ca2+](er)) and ER stress have been proposed to be involved in oxidative toxicity. Nevertheless, their relative involvements in the processes leading to cell death are not well defined. In this study, we investigated whether oxidative stress generated during ascorbate-driven menadione redox cycling (Asc/Men) could trigger these three events, and, if so, whether they contributed to Asc/Men cytoxicity in MCF-7 cells. Using microspectrofluorimetry, we demonstrated that Asc/Men-generated oxidative stress was associated with a slow and moderate increase in [Ca2+](c), largely preceding permeation of propidium iodide, and thus cell death. Asc/Men treatment was shown to partially deplete ER calcium stores after 90 min (decrease by 45% compared to control). This event was associated with ER stress activation, as shown by analysis of eIF2 phosphorylation and expression of the molecular chaperone GRP94. Thapsigargin (TG) was then used to study the effect of complete [Ca2+](er) emptying during the oxidative stress generated by Asc/Men. Surprisingly, the combination of TG and Asc/Men increased ER stress to a level considerably higher than that observed for either treatment alone, suggesting that [Ca2+](er) release alone is not sufficient to explain ER stress activation during oxidative stress. Finally, TG-mediated [Ca2+](er) release largely potentiated ER stress, DNA fragmentation and cell death caused by Asc/Men, supporting a role of ER stress in the process of Asc/Men cytotoxicity. Taken together, our results highlight the involvement of ER stress and [Ca2+](er) decrease in the process of oxidative stress-induced cell death in MCF-7 cells.

  6. Spike, a novel BH3-only protein, regulates apoptosis at the endoplasmic reticulum.

    PubMed

    Mund, Thomas; Gewies, Andreas; Schoenfeld, Nicole; Bauer, Manuel K A; Grimm, Stefan

    2003-04-01

    We have isolated Spike, a novel and evolutionary conserved BH3-only protein. BH3-only proteins constitute a family of apoptosis inducers that mediate proapoptotic signals. In contrast to most proteins of this family, Spike was not found to be associated with mitochondria. Furthermore, unlike the known BH3-only proteins, Spike could not interact with all tested Bcl-2 family members, despite its BH3 domain being necessary for cell killing. Our findings indicate that Spike is localized to the endoplasmic reticulum. The endoplasmic reticulum is an organelle that has only recently been implicated in regulation of apoptosis. At this locale, Spike interacts with Bap31, an adaptor protein for pro-caspase-8 and Bcl-XL. In doing so, Spike is able to inhibit the formation of a complex between Bap31 and the antiapoptotic Bcl-XL protein. Furthermore, Spike transmits the signal of specific death receptors. Its down-regulation in certain tumors suggests that Spike may also play a role in tumorigenesis. Our findings add new insight for how BH3-only and antiapoptotic Bcl-2 proteins regulate cell death.

  7. Evidence for Increased Response to Induced Endoplasmic Reticulum Stress in Myeloid Cells in Acquired Aplastic Anemia.

    PubMed

    Sidhu, Alpa; Callaghan, Michael U; Gadgeel, Manisha S; Buck, Steven A; Fribley, Andrew M; Savaşan, Süreyya

    2017-04-01

    Autoimmune response targeting the hematopoietic stem cells highlights the current understanding of acquired aplastic anemia (AAA) pathogenesis. Upregulation of the unfolded protein response is the cell's rejoinder to a variety of stresses, which either result in restoring homeostasis or cell death by increased expression of the transcription factor C/EBP homologous protein. We hypothesized that there is an inherent increased sensitivity to various cellular stressors, including the ones that target endoplasmic reticulum (ER) in AAA leading to a decreased proliferation and potentially contributing to susceptibility to autologous cytotoxicity. Using archived bone marrow aspirate samples, we demonstrate that the culture-expanded AAA myeloid cells have an increased response to ER stress induced by tunicamycin leading to decreased cell proliferation. Within the AAA myeloid samples, we show that the disease status, active versus response to therapy at the time of sampling does not alter the ER stress response. This is the first report, which provides evidence for an inherent defective stress control in the myeloid cells as a possible mechanism of evolution of the disease process in AAA.

  8. Dysregulation of Endoplasmic Reticulum Stress and Autophagic Responses by the Antiretroviral Drug Efavirenz

    PubMed Central

    Bertrand, Luc

    2015-01-01

    Increasing evidence demonstrates that the antiretroviral drugs (ARVds) used for human immunodeficiency virus (HIV) treatment have toxic effects that result in various cellular and tissue pathologies; however, their impact on the cells composing the blood-brain barrier is poorly understood. The current study focused on ARVds, used either in combination or alone, on the induction of endoplasmic reticulum (ER) stress responses in human brain endothelial cells. Among studied drugs (efavirenz, tenofovir, emtricitabine, lamivudine, and indinavir), only efavirenz increased ER stress via upregulation and activation of protein kinase-like ER kinase PERK and inositol requiring kinase 1α (IRE1α). At the same time, efavirenz diminished autophagic activity, a surprising result because typically the induction of ER stress is linked to enhanced autophagy. These results were confirmed in microvessels of HIV transgenic mice chronically administered with efavirenz. In a series of further experiments, we identified that efavirenz dysregulated ER stress and autophagy by blocking the activity of the Beclin-1/Atg14/PI3KIII complex in regard to synthesis of phosphatidylinositol 3-phosphate, a process that is linked to the formation of autophagosomes. Because autophagy is a protective mechanism involved in the removal of dysfunctional proteins and organelles, its inhibition can contribute to the toxicity of efavirenz or the development of neurodegenerative disease in HIV patients treated with this drug. PMID:25987489

  9. Miltirone exhibits antileukemic activity by ROS-mediated endoplasmic reticulum stress and mitochondrial dysfunction pathways

    PubMed Central

    Zhou, Ling; Jiang, Lifeng; Xu, Maolei; Liu, Qun; Gao, Ning; Li, Ping; Liu, E-Hu

    2016-01-01

    In this study, we investigated the effects of miltirone in human leukemia cell lines, primary leukemia cells, and nude mice U937 xenograft. Treatment of cells with miltirone resulted in apoptosis, mitochondria membrane potential (MMP) collapses, increase of Bax/Bcl-2 ratio, and cytochrome c release. Miltirone triggered the endoplasmic reticulum (ER) stress identified through several key molecules of the unfolded protein response, including phosphorylated PERK, eIF2a, GRP78, GRP94, and caspase-12. Miltrone treatment also resulted in the release of Ca2+ from the ER stores and mitochondrial Ca2+ loading in the cells. Further research revealed that miltirone resulted in dose-dependent decrease in complex III activity and elevated reactive oxygen species (ROS) production in these cells. Miltirone-induced apoptosis, dissipation of MMP and ER stress were dramatically blocked by pretreatment with antioxidant N-acetylcysteine (NAC). In contrast, treatment with ER stress inhibitor TUDCA significantly attenuated miltirone-induced ROS and apoptosis in leukemia cells. Moreover, our in vivo findings showed that administration of miltirone markedly inhibited tumor growth and induced apoptosis in U937 xenograft model with low systemic toxicity. Taken together, these findings indicate that miltirone may exert its antileukemic activity by inducing apoptosis through a ROS-dependent destructive cycle involving ER stress and mitochondrial dysfunction. PMID:26848099

  10. Vitamin E δ-tocotrienol triggers endoplasmic reticulum stress-mediated apoptosis in human melanoma cells

    PubMed Central

    Montagnani Marelli, Marina; Marzagalli, Monica; Moretti, Roberta M.; Beretta, Giangiacomo; Casati, Lavinia; Comitato, Raffaella; Gravina, Giovanni L.; Festuccia, Claudio; Limonta, Patrizia

    2016-01-01

    Malignant melanoma is the leading cause of death from skin cancer. Drug toxicity and resistance represent a serious challange for melanoma treatments. Evidence demonstrates that natural compounds may play a crucial role in cancer prevention, growth and progression. Vitamin E tocotrienols (TT) were shown to possess antitumor activity. Here, we analyzed the effects of δ-TT on melanoma cell growth and the involvement of the endoplasmic reticulum (ER) stress in this activity. The experiments were performed on human melanoma cell lines, BLM and A375. δ-TT exerted a significant proapoptotic effect on both cell lines, involving the intrinsic apoptosis pathway; importantly, this compound did not affect the viability of normal human melanocytes. In melanoma cells, δ-TT exerted its antitumor effect through activation of the PERK/p-eIF2α/ATF4/CHOP, IRE1α and caspase-4 ER stress-related branches. Salubrinal, an inhibitor of the ER stress, counteracted the cytotoxic activity of δ-TT. In vivo experiments performed in nude mice bearing A375 xenografts evidenced that δ-TT reduces tumor volume and tumor mass; importantly, tumor progression was significantly delayed by δ-TT treatment. In conclusion, δ-TT exerts a proapoptotic activity on melanoma cells, through activation of the ER stress-related pathways. δ-TT might represent an effective option for novel chemopreventive/therapeutic strategies for melanoma. PMID:27461002

  11. Mitochondrial cholesterol accumulation in alcoholic liver disease: Role of ASMase and endoplasmic reticulum stress.

    PubMed

    Marí, Montserrat; Morales, Albert; Colell, Anna; García-Ruiz, Carmen; Fernández-Checa, Jose C

    2014-01-01

    Alcoholic liver disease (ALD) is a major cause of chronic liver disease and a growing health concern in theworld. While the pathogenesis of ALD is poorly characterized key players identified in experimental models and patients, such as perturbations in mitochondrial structure and function, selective loss of antioxidant defense and susceptibility to inflammatory cytokines, contribute to ALD progression. Both oxidative stress and mitochondrial dysfunction compromise essential cellular functions and energy generation and hence are important pathogenic mechanisms of ALD. An important process mediating the mitochondrial disruption induced by alcohol intake is the trafficking of cholesterol to mitochondria, mediated by acid sphingomyelinase-induced endoplasmic reticulum stress, which contributes to increased cholesterol synthesis and StARD1upregulation. Mitochondrial cholesterol accumulation not only sensitizes to oxidative stress but it can contribute to the metabolic reprogramming in ALD, manifested by activation of the hypoxia inducible transcription factor 1 and stimulation of glycolysis and lactate secretion. Thus, a better understanding of the mechanisms underlying alcohol-mediated mitochondrial impairment and oxidative stress may lead to the identification of novel treatments for ALD. The present review briefly summarizes current knowledge on the cellular and molecular mechanisms contributing to alcohol-induced mitochondrial dysfunction and cholesterol accumulation and provides insights for potential therapeutic targets in ALD.

  12. Unexpected blockade of adipocyte differentiation by K-7174: Implication for endoplasmic reticulum stress

    SciTech Connect

    Shimada, Tsuyoshi; Hiramatsu, Nobuhiko; Okamura, Maro; Hayakawa, Kunihiro; Kasai, Ayumi; Yao, Jian; Kitamura, Masanori

    2007-11-16

    Preadipocytes constitutively express GATA-2 and GATA-3 that are required to halt the cells at the undifferentiated stage. However, we unexpectedly found that K-7174, a GATA-specific inhibitor, did not induce but rather inhibited differentiation of 3T3-L1 preadipocytes. It was associated with lack of lipid accumulation, blunted expression of adipocyte markers including adiponectin and peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}), and sustained expression of a preadipocyte marker monocyte chemoattractant protein 1 (MCP-1). Subsequent experiments revealed that K-7174 had the potential to induce endoplasmic reticulum (ER) stress evidenced by induction of GRP78 and CHOP. Other inducers of ER stress completely reproduced the effects of K-7174 including suppression of lipid accumulation, blockade of induction of adiponection and PPAR{gamma} and maintenance of MCP-1 expression. These results indicated a possibility that ER stress suppresses adipocyte differentiation and that GATA inhibitor K-7174 has the potential for interfering with adipogenesis through induction of ER stress.

  13. A small deletion in SERPINC1 causes type I antithrombin deficiency by promoting endoplasmic reticulum stress

    PubMed Central

    Cai, Lei; Zhang, Xin; Zhai, Yu; Liu, Jianren

    2016-01-01

    Antithrombin (AT) deficiency is an autosomal dominant disorder, and identification of mutation AT variants would improve our understanding of the anticoagulant function of this serine protease inhibitor (SERPIN) and the molecular pathways underlying this disorder. In the present study, we performed whole-exome sequencing of a Chinese family with deep vein thrombosis, and identified a new small deletion that eliminates four amino acids (INEL) from exon 4 of SERPINC1 gene. This causes type I AT deficiency by enhancing the intracellular retention of this protein. AT retention leads to endoplasmic reticulum (ER) stress, which further inhibits AT release. In addition, ER stress activates ER-associated degradation, which promotes AT degradation. Suppression of ER stress enhanced the secretion of AT, while inhibition of ER-associated degradation suppressed AT release. Thus, our study identified a new mutation (INEL deletion) causing type I AT deficiency, and uncovered a novel mechanism for AT retention through enhanced ER stress, which may provide an innovative approach for treating AT deficiency. PMID:27708219

  14. Vitamin E δ-tocotrienol triggers endoplasmic reticulum stress-mediated apoptosis in human melanoma cells.

    PubMed

    Montagnani Marelli, Marina; Marzagalli, Monica; Moretti, Roberta M; Beretta, Giangiacomo; Casati, Lavinia; Comitato, Raffaella; Gravina, Giovanni L; Festuccia, Claudio; Limonta, Patrizia

    2016-07-27

    Malignant melanoma is the leading cause of death from skin cancer. Drug toxicity and resistance represent a serious challange for melanoma treatments. Evidence demonstrates that natural compounds may play a crucial role in cancer prevention, growth and progression. Vitamin E tocotrienols (TT) were shown to possess antitumor activity. Here, we analyzed the effects of δ-TT on melanoma cell growth and the involvement of the endoplasmic reticulum (ER) stress in this activity. The experiments were performed on human melanoma cell lines, BLM and A375. δ-TT exerted a significant proapoptotic effect on both cell lines, involving the intrinsic apoptosis pathway; importantly, this compound did not affect the viability of normal human melanocytes. In melanoma cells, δ-TT exerted its antitumor effect through activation of the PERK/p-eIF2α/ATF4/CHOP, IRE1α and caspase-4 ER stress-related branches. Salubrinal, an inhibitor of the ER stress, counteracted the cytotoxic activity of δ-TT. In vivo experiments performed in nude mice bearing A375 xenografts evidenced that δ-TT reduces tumor volume and tumor mass; importantly, tumor progression was significantly delayed by δ-TT treatment. In conclusion, δ-TT exerts a proapoptotic activity on melanoma cells, through activation of the ER stress-related pathways. δ-TT might represent an effective option for novel chemopreventive/therapeutic strategies for melanoma.

  15. Proline biosynthesis is required for endoplasmic reticulum stress tolerance in Saccharomyces cerevisiae.

    PubMed

    Liang, Xinwen; Dickman, Martin B; Becker, Donald F

    2014-10-03

    The amino acid proline is uniquely involved in cellular processes that underlie stress response in a variety of organisms. Proline is known to minimize protein aggregation, but a detailed study of how proline impacts cell survival during accumulation of misfolded proteins in the endoplasmic reticulum (ER) has not been performed. To address this we examined in Saccharomyces cerevisiae the effect of knocking out the PRO1, PRO2, and PRO3 genes responsible for proline biosynthesis. The null mutants pro1, pro2, and pro3 were shown to have increased sensitivity to ER stress relative to wild-type cells, which could be restored by proline or the corresponding genetic complementation. Of these mutants, pro3 was the most sensitive to tunicamycin and was rescued by anaerobic growth conditions or reduced thiol reagents. The pro3 mutant cells have higher intracellular reactive oxygen species, total glutathione, and a NADP(+)/NADPH ratio than wild-type cells under limiting proline conditions. Depletion of proline biosynthesis also inhibits the unfolded protein response (UPR) indicating proline protection involves the UPR. To more broadly test the role of proline in ER stress, increased proline biosynthesis was shown to partially rescue the ER stress sensitivity of a hog1 null mutant in which the high osmolality pathway is disrupted.

  16. The Role of p58IPK in Protecting the Stressed Endoplasmic Reticulum

    PubMed Central

    Rutkowski, D. Thomas; Kang, Sang-Wook; Goodman, Alan G.; Garrison, Jennifer L.; Taunton, Jack; Katze, Michael G.

    2007-01-01

    The preemptive quality control (pQC) pathway protects cells from acute endoplasmic reticulum (ER) stress by attenuating translocation of nascent proteins despite their targeting to translocons at the ER membrane. Here, we investigate the hypothesis that the DnaJ protein p58IPK plays an essential role in this process via HSP70 recruitment to the cytosolic face of translocons for extraction of translocationally attenuated nascent chains. Our analyses revealed that the heightened stress sensitivity of p58−/− cells was not due to an impairment of the pQC pathway or elevated ER substrate burden during acute stress. Instead, the lesion was in the protein processing capacity of the ER lumen, where p58IPK was found to normally reside in association with BiP. ER lumenal p58IPK could be coimmunoprecipitated with a newly synthesized secretory protein in vitro and stimulated protein maturation upon overexpression in cells. These results identify a previously unanticipated location for p58IPK in the ER lumen where its putative function as a cochaperone explains the stress-sensitivity phenotype of knockout cells and mice. PMID:17567950

  17. A small deletion in SERPINC1 causes type I antithrombin deficiency by promoting endoplasmic reticulum stress.

    PubMed

    Su, Jingjing; Shu, Liang; Zhang, Zhou; Cai, Lei; Zhang, Xin; Zhai, Yu; Liu, Jianren

    2016-11-22

    Antithrombin (AT) deficiency is an autosomal dominant disorder, and identification of mutation AT variants would improve our understanding of the anticoagulant function of this serine protease inhibitor (SERPIN) and the molecular pathways underlying this disorder. In the present study, we performed whole-exome sequencing of a Chinese family with deep vein thrombosis, and identified a new small deletion that eliminates four amino acids (INEL) from exon 4 of SERPINC1 gene. This causes type I AT deficiency by enhancing the intracellular retention of this protein. AT retention leads to endoplasmic reticulum (ER) stress, which further inhibits AT release. In addition, ER stress activates ER-associated degradation, which promotes AT degradation. Suppression of ER stress enhanced the secretion of AT, while inhibition of ER-associated degradation suppressed AT release. Thus, our study identified a new mutation (INEL deletion) causing type I AT deficiency, and uncovered a novel mechanism for AT retention through enhanced ER stress, which may provide an innovative approach for treating AT deficiency.

  18. The Endoplasmic Reticulum Resident Protein AGR3. Required for Regulation of Ciliary Beat Frequency in the Airway.

    PubMed

    Bonser, Luke R; Schroeder, Bradley W; Ostrin, Lisa A; Baumlin, Nathalie; Olson, Jean L; Salathe, Matthias; Erle, David J

    2015-10-01

    Protein disulfide isomerase (PDI) family members regulate protein folding and calcium homeostasis in the endoplasmic reticulum (ER). The PDI family member anterior gradient (AGR) 3 is expressed in the airway, but the localization, regulation, and function of AGR3 are poorly understood. Here we report that AGR3, unlike its closest homolog AGR2, is restricted to ciliated cells in the airway epithelium and is not induced by ER stress. Mice lacking AGR3 are viable and develop ciliated cells with normal-appearing cilia. However, ciliary beat frequency was lower in airways from AGR3-deficient mice compared with control mice (20% lower in the absence of stimulation and 35% lower after ATP stimulation). AGR3 deficiency had no detectable effects on ciliary beat frequency (CBF) when airways were perfused with a calcium-free solution, suggesting that AGR3 is required for calcium-mediated regulation of ciliary function. Decreased CBF was associated with impaired mucociliary clearance in AGR3-deficient airways. We conclude that AGR3 is a specialized member of the PDI family that plays an unexpected role in the regulation of CBF and mucociliary clearance in the airway.

  19. Hydrogen Sulfide Improves Vascular Calcification in Rats by Inhibiting Endoplasmic Reticulum Stress

    PubMed Central

    Yang, Rui; Teng, Xu; Li, Hui; Xue, Hong-Mei; Guo, Qi; Xiao, Lin; Wu, Yu-Ming

    2016-01-01

    In this study, the vitamin D3 plus nicotine (VDN) model of rats was used to prove that H2S alleviates vascular calcification (VC) and phenotype transformation of vascular smooth muscle cells (VSMC). Besides, H2S can also inhibit endoplasmic reticulum stress (ERS) of calcified aortic tissues. The effect of H2S on alleviating VC and phenotype transformation of VSMC can be blocked by TM, while PBA also alleviated VC and phenotype transformation of VSMC that was similar to the effect of H2S. These results suggest that H2S may alleviate rat aorta VC by inhibiting ERS, providing new target and perspective for prevention and treatment of VC. PMID:27022436

  20. The roles of endoplasmic reticulum stress response in female mammalian reproduction.

    PubMed

    Yang, Yanzhou; Pei, Xiuying; Jin, Yaping; Wang, Yanrong; Zhang, Cheng

    2016-03-01

    Endoplasmic reticulum stress (ERS) activates a protective pathway, called the unfold protein response, for maintaining cellular homeostasis, but cellular apoptosis is triggered by excessive or persistent ERS. Several recent studies imply that the ERS response might have broader physiological roles in the various reproductive processes of female mammals, including embryo implantation, decidualization, preimplantation embryonic development, follicle atresia, and the development of the placenta. This review summarizes the existing data concerning the molecular and biological roles of the ERS response. The study of the functions of the ERS response in mammalian reproduction might provide novel insights into and an understanding of reproductive cell survival and apoptosis under physiological and pathological conditions. The ERS response is a novel signaling pathway for reproductive cell survival and apoptosis. Infertility might be a result of disturbing the ERS response during the process of female reproduction.

  1. Salubrinal Alleviates Pressure Overload-Induced Cardiac Hypertrophy by Inhibiting Endoplasmic Reticulum Stress Pathway

    PubMed Central

    Rani, Shilpa; Sreenivasaiah, Pradeep Kumar; Cho, Chunghee; Kim, Do Han

    2017-01-01

    Pathological hypertrophy of the heart is closely associated with endoplasmic reticulum stress (ERS), leading to maladaptations such as myocardial fibrosis, induction of apoptosis, and cardiac dysfunctions. Salubrinal is a known selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phospho-eukaryotic translation initiation factor 2 subunit (p-eIF2)-α, the key signaling process in the ERS pathway. In this study, the effects of salubrinal were examined on cardiac hypertrophy using the mouse model of transverse aortic constriction (TAC) and cell model of neonatal rat ventricular myocytes (NRVMs). Treatment of TAC-induced mice with salubrinal (0.5 mg·kg−1·day−1) alleviated cardiac hypertrophy and tissue fibrosis. Salubrinal also alleviated hypertrophic growth in endothelin 1 (ET1)-treated NRVMs. Therefore, the present results suggest that salubrinal may be a potentially efficacious drug for treating pathological cardiac remodeling. PMID:28152298

  2. Sulfur mustard induces an endoplasmic reticulum stress response in the mouse ear vesicant model

    SciTech Connect

    Chang, Yoke-Chen; Wang, James D.; Svoboda, Kathy K.; Casillas, Robert P.; Laskin, Jeffrey D.; Gordon, Marion K.; Gerecke, Donald R.

    2013-04-15

    The endoplasmic reticulum (ER) stress response is a cell survival pathway upregulated when cells are under severe stress. Severely damaged mouse ear skin exposed to the vesicant, sulfur mustard (bis-2-chloroethyl sulfide, SM), resulted in increased expression of ER chaperone proteins that accompany misfolded and incorrectly made proteins targeted for degradation. Time course studies with SM using the mouse ear vesicant model (MEVM) showed progressive histopathologic changes including edema, separation of the epidermis from the dermis, persistent inflammation, upregulation of laminin γ2 (one of the chains of laminin-332, a heterotrimeric skin glycoprotein required for wound repair), and delayed wound healing from 24 h to 168 h post exposure. This was associated with time related increased expression of the cell survival ER stress marker, GRP78/BiP, and the ER stress apoptosis marker, GADD153/CHOP, suggesting simultaneous activation of both cell survival and non-mitochondrial apoptosis pathways. Dual immunofluorescence labeling of a keratinocyte migration promoting protein, laminin γ2 and GRP78/BIP, showed colocalization of the two molecules 72 h post exposure indicating that the laminin γ2 was misfolded after SM exposure and trapped within the ER. Taken together, these data show that ER stress is induced in mouse skin within 24 h of vesicant exposure in a defensive response to promote cell survival; however, it appears that this response is rapidly overwhelmed by the apoptotic pathway as a consequence of severe SM-induced injury. - Highlights: ► We demonstrated ER stress response in the mouse ear vesicant model. ► We described the asymmetrical nature of wound repair in the MEVM. ► We identified the distribution of various ER stress markers in the MEVM.

  3. Humanin Protects RPE Cells from Endoplasmic Reticulum Stress-Induced Apoptosis by Upregulation of Mitochondrial Glutathione

    PubMed Central

    Matsunaga, Douglas; Sreekumar, Parameswaran G.; Ishikawa, Keijiro; Terasaki, Hiroto; Barron, Ernesto; Cohen, Pinchas

    2016-01-01

    Humanin (HN) is a small mitochondrial-encoded peptide with neuroprotective properties. We have recently shown protection of retinal pigmented epithelium (RPE) cells by HN in oxidative stress; however, the effect of HN on endoplasmic reticulum (ER) stress has not been evaluated in any cell type. Our aim here was to study the effect of HN on ER stress-induced apoptosis in RPE cells with a specific focus on ER-mitochondrial cross-talk. Dose dependent effects of ER stressors (tunicamycin (TM), brefeldin A, and thapsigargin) were studied after 12 hr of treatment in confluent primary human RPE cells with or without 12 hr of HN pretreatment (1–20 μg/mL). All three ER stressors induced RPE cell apoptosis in a dose dependent manner. HN pretreatment significantly decreased the number of apoptotic cells with all three ER stressors in a dose dependent manner. HN pretreatment similarly protected U-251 glioma cells from TM-induced apoptosis in a dose dependent manner. HN pretreatment significantly attenuated activation of caspase 3 and ER stress-specific caspase 4 induced by TM. TM treatment increased mitochondrial superoxide production, and HN co-treatment resulted in a decrease in mitochondrial superoxide compared to TM treatment alone. We further showed that depleted mitochondrial glutathione (GSH) levels induced by TM were restored with HN co-treatment. No significant changes were found for the expression of several antioxidant enzymes between TM and TM plus HN groups except for the expression of glutamylcysteine ligase catalytic subunit (GCLC), the rate limiting enzyme required for GSH biosynthesis, which is upregulated with TM and TM+HN treatment. These results demonstrate that ER stress promotes mitochondrial alterations in RPE that lead to apoptosis. We further show that HN has a protective effect against ER stress-induced apoptosis by restoring mitochondrial GSH. Thus, HN should be further evaluated for its therapeutic potential in disorders linked to ER stress. PMID

  4. Humanin Protects RPE Cells from Endoplasmic Reticulum Stress-Induced Apoptosis by Upregulation of Mitochondrial Glutathione.

    PubMed

    Matsunaga, Douglas; Sreekumar, Parameswaran G; Ishikawa, Keijiro; Terasaki, Hiroto; Barron, Ernesto; Cohen, Pinchas; Kannan, Ram; Hinton, David R

    2016-01-01

    Humanin (HN) is a small mitochondrial-encoded peptide with neuroprotective properties. We have recently shown protection of retinal pigmented epithelium (RPE) cells by HN in oxidative stress; however, the effect of HN on endoplasmic reticulum (ER) stress has not been evaluated in any cell type. Our aim here was to study the effect of HN on ER stress-induced apoptosis in RPE cells with a specific focus on ER-mitochondrial cross-talk. Dose dependent effects of ER stressors (tunicamycin (TM), brefeldin A, and thapsigargin) were studied after 12 hr of treatment in confluent primary human RPE cells with or without 12 hr of HN pretreatment (1-20 μg/mL). All three ER stressors induced RPE cell apoptosis in a dose dependent manner. HN pretreatment significantly decreased the number of apoptotic cells with all three ER stressors in a dose dependent manner. HN pretreatment similarly protected U-251 glioma cells from TM-induced apoptosis in a dose dependent manner. HN pretreatment significantly attenuated activation of caspase 3 and ER stress-specific caspase 4 induced by TM. TM treatment increased mitochondrial superoxide production, and HN co-treatment resulted in a decrease in mitochondrial superoxide compared to TM treatment alone. We further showed that depleted mitochondrial glutathione (GSH) levels induced by TM were restored with HN co-treatment. No significant changes were found for the expression of several antioxidant enzymes between TM and TM plus HN groups except for the expression of glutamylcysteine ligase catalytic subunit (GCLC), the rate limiting enzyme required for GSH biosynthesis, which is upregulated with TM and TM+HN treatment. These results demonstrate that ER stress promotes mitochondrial alterations in RPE that lead to apoptosis. We further show that HN has a protective effect against ER stress-induced apoptosis by restoring mitochondrial GSH. Thus, HN should be further evaluated for its therapeutic potential in disorders linked to ER stress.

  5. Excessive training is associated with endoplasmic reticulum stress but not apoptosis in the hypothalamus of mice.

    PubMed

    Pinto, Ana Paula; da Rocha, Alisson Luiz; Pereira, Bruno Cesar; Oliveira, Luciana da Costa; Morais, Gustavo Paroschi; Moura, Leandro Pereira; Ropelle, Eduardo Rochete; Pauli, José Rodrigo; da Silva, Adelino Sanchez Ramos

    2016-12-05

    Downhill running-based overtraining model increases the hypothalamic levels of IL-1β, TNF-α, SOCS3, and pSAPK-JNK. The aim of the present study was to verify the effects of 3 overtraining protocols on the levels of BiP, pIRE-1 (Ser724), pPERK (Thr981), pelF2α (Ser52), ATF-6, GRP-94, caspase 4, caspase 12, pAKT (Ser473), pmTOR (Ser2448), and pAMPK (Thr172) proteins in the mouse hypothalamus. The mice were randomized into the control, overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up), and overtrained by running without inclination (OTR) groups. After the overtraining protocols (i.e., at the end of week 8), hypothalamus was removed and used for immunoblotting. The OTR/down group exhibited increased levels of all of the analyzed endoplasmic reticulum stress markers in the hypothalamus at the end of week 8. The OTR/up and OTR groups exhibited increased levels of BiP, pIRE-1 (Ser724), and pPERK (Thr981) in the hypothalamus at the end of week 8. There were no significant differences in the levels of caspase 4, caspase 12, pAKT (Ser473), pmTOR (Ser2448), and pAMPK (Thr172) between the experimental groups at the end of week 8. In conclusion, the 3 overtraining protocols increased the endoplasmic reticulum stress at the end of week 8.

  6. Nonesterified Fatty Acid-Induced Endoplasmic Reticulum Stress in Cattle Cumulus Oocyte Complexes Alters Cell Metabolism and Developmental Competence.

    PubMed

    Sutton-McDowall, Melanie L; Wu, Linda L Y; Purdey, Malcolm; Abell, Andrew D; Goldys, Ewa M; MacMillan, Keith L; Thompson, Jeremy G; Robker, Rebecca L

    2016-01-01

    Reduced oocyte quality has been associated with poor fertility of high-performance dairy cows during peak lactation, due to negative energy balance. We examined the role of nonesterified fatty acids (NEFAs), known to accumulate within follicular fluid during under- and overnutrition scenarios, in causing endoplasmic reticulum (ER) stress of in vitro maturated cattle cumulus-oocyte complexes (COCs). NEFA concentrations were: palmitic acid (150 μM), oleic acid (200 μM), and steric acid (75 μM). Abattoir-derived COCs were randomly matured for 24 h in the presence of NEFAs and/or an ER stress inhibitor, salubrinal. Total and hatched blastocyst yields were negatively impacted by NEFA treatment compared with controls, but this was reversed by salubrinal. ER stress markers, activating transcription factor 4 (Atf4) and heat shock protein 5 (Hspa5), but not Atf6, were significantly up-regulated by NEFA treatment within whole COCs but reversed by coincubation with salubrinal. Likewise, glucose uptake and lactate production, measured in spent medium samples, showed a similar pattern, suggesting that cumulus cell metabolism is sensitive to NEFAs via an ER stress-mediated process. In contrast, while mitochondrial DNA copy number was recovered in NEFA-treated oocytes, oocyte autofluorescence of the respiratory chain cofactor, FAD, was lower following NEFA treatment of COCs, and this was not reversed by salubrinal, suggesting the negative impact was via reduced mitochondrial function. These results reveal the significance of NEFA-induced ER stress on bovine COC developmental competence, revealing a potential therapeutic target for improving oocyte quality during peak lactation.

  7. Identification of a calmodulin-regulated Ca2+-ATPase in the endoplasmic reticulum

    NASA Technical Reports Server (NTRS)

    Hong, B.; Ichida, A.; Wang, Y.; Gens, J. S.; Pickard, B. G.; Harper, J. F.; Evans, M. L. (Principal Investigator)

    1999-01-01

    A unique subfamily of calmodulin-dependent Ca2+-ATPases was recently identified in plants. In contrast to the most closely related pumps in animals, plasma membrane-type Ca2+-ATPases, members of this new subfamily are distinguished by a calmodulin-regulated autoinhibitor located at the N-terminal instead of a C-terminal end. In addition, at least some isoforms appear to reside in non-plasma membrane locations. To begin delineating their functions, we investigated the subcellular localization of isoform ACA2p (Arabidopsis Ca2+-ATPase, isoform 2 protein) in Arabidopsis. Here we provide evidence that ACA2p resides in the endoplasmic reticulum (ER). In buoyant density sucrose gradients performed with and without Mg2+, ACA2p cofractionated with an ER membrane marker and a typical "ER-type" Ca2+-ATPase, ACA3p/ECA1p. To visualize its subcellular localization, ACA2p was tagged with a green fluorescence protein at its C terminus (ACA2-GFPp) and expressed in transgenic Arabidopsis. We collected fluorescence images from live root cells using confocal and computational optical-sectioning microscopy. ACA2-GFPp appeared as a fluorescent reticulum, consistent with an ER location. In addition, we observed strong fluorescence around the nuclei of mature epidermal cells, which is consistent with the hypothesis that ACA2p may also function in the nuclear envelope. An ER location makes ACA2p distinct from all other calmodulin-regulated pumps identified in plants or animals.

  8. The regulation of sarco(endo)plasmic reticulum calcium-ATPases (SERCA).

    PubMed

    Stammers, Andrew N; Susser, Shanel E; Hamm, Naomi C; Hlynsky, Michael W; Kimber, Dustin E; Kehler, D Scott; Duhamel, Todd A

    2015-10-01

    The sarco(endo)plasmic reticulum calcium ATPase (SERCA) is responsible for transporting calcium (Ca(2+)) from the cytosol into the lumen of the sarcoplasmic reticulum (SR) following muscular contraction. The Ca(2+) sequestering activity of SERCA facilitates muscular relaxation in both cardiac and skeletal muscle. There are more than 10 distinct isoforms of SERCA expressed in different tissues. SERCA2a is the primary isoform expressed in cardiac tissue, whereas SERCA1a is the predominant isoform expressed in fast-twitch skeletal muscle. The Ca(2+) sequestering activity of SERCA is regulated at the level of protein content and is further modified by the endogenous proteins phospholamban (PLN) and sarcolipin (SLN). Additionally, several novel mechanisms, including post-translational modifications and microRNAs (miRNAs) are emerging as integral regulators of Ca(2+) transport activity. These regulatory mechanisms are clinically relevant, as dysregulated SERCA function has been implicated in the pathology of several disease states, including heart failure. Currently, several clinical trials are underway that utilize novel therapeutic approaches to restore SERCA2a activity in humans. The purpose of this review is to examine the regulatory mechanisms of the SERCA pump, with a particular emphasis on the influence of exercise in preventing the pathological conditions associated with impaired SERCA function.

  9. Chronic restraint stress promotes learning and memory impairment due to enhanced neuronal endoplasmic reticulum stress in the frontal cortex and hippocampus in male mice.

    PubMed

    Huang, Rong-Rong; Hu, Wen; Yin, Yan-Yan; Wang, Yu-Chan; Li, Wei-Ping; Li, Wei-Zu

    2015-02-01

    Chronic stress has been implicated in many types of neurodegenerative diseases, such as Alzheimer's disease (AD). In our previous study, we demonstrated that chronic restraint stress (CRS) induced reactive oxygen species (ROS) overproduction and oxidative damage in the frontal cortex and hippocampus in mice. In the present study, we investigated the effects of CRS (over a period of 8 weeks) on learning and memory impairment and endoplasmic reticulum (ER) stress in the frontal cortex and hippocampus in male mice. The Morris water maze was used to investigate the effects of CRS on learning and memory impairment. Immunohistochemistry and immunoblot analysis were also used to determine the expression levels of protein kinase C α (PKCα), 78 kDa glucose-regulated protein (GRP78), C/EBP-homologous protein (CHOP) and mesencephalic astrocyte-derived neurotrophic factor (MANF). The results revealed that CRS significantly accelerated learning and memory impairment, and induced neuronal damage in the frontal cortex and hippocampus CA1 region. Moreover, CRS significantly increased the expression of PKCα, CHOP and MANF, and decreased that of GRP78 in the frontal cortex and hippocampus. Our data suggest that exposure to CRS (for 8 weeks) significantly accelerates learning and memory impairment, and the mechanisms involved may be related to ER stress in the frontal cortex and hippocampus.

  10. Disturbance of hippocampal H2S generation contributes to CUMS-induced depression-like behavior: involvement in endoplasmic reticulum stress of hippocampus.

    PubMed

    Tan, Huiying; Zou, Wei; Jiang, Jiamei; Tian, Ying; Xiao, Zhifang; Bi, Lili; Zeng, Haiying; Tang, Xiaoqing

    2015-04-01

    The chronic unpredictable mild stress (CUMS) model is a widely used experimental model of depression. Exogenous stress-induced neuronal cell death in the hippocampus is closely associated with the pathogenesis of depression. Excessive and prolonged endoplasmic reticulum (ER) stress triggers cell death. Hydrogen sulfide (H2S), the third endogenous signaling gasotransmitter, plays an important role in brain functions as a neuromodulator and a neuroprotectant. We hypothesized that the disturbance of endogenous H2S generation and ER stress in the hippocampus might be involved in CUMS-induced depression-like behaviors. Thus, the present study focused on whether CUMS disturbs the generation of endogenous H2S and up-regulates ER stress in the hippocampus and whether exogenous H2S prevents CUMS-induced depressive-like behaviors. Results showed that CUMS-treated rats exhibit depression-like behavior and hippocampal ER stress responses including up-regulated levels of glucose-regulated protein 78, CCAAT/enhancer binding protein homologous protein, and cleaved caspase-12 expression, while the endogenous generation of H2S in the hippocampus is suppressed in CUMS-treated rats. Furthermore, exogenous H2S prevents CUMS-induced depression-like behavior. These data indicated that CUMS-induced depression-like behaviors are related to the disturbance of endogenous H2S generation and ER stress in the hippocampus and suggested that endogenous H2S and ER stress are novel treatment targets of depression.

  11. Nur77 exacerbates PC12 cellular injury in vitro by aggravating mitochondrial impairment and endoplasmic reticulum stress

    PubMed Central

    Gao, Huimin; Chen, Zhaoyu; Fu, Yongmei; Yang, Xiaoyan; Weng, Ruihui; Wang, Rui; Lu, Jianjun; Pan, Mengqiu; Jin, Kunlin; McElroy, Chris; Tang, Beisha; Xia, Ying; Wang, Qing

    2016-01-01

    The nuclear orphan receptor, Nur77 plays important roles in neuroimflammation, apoptosis, and dopaminergic neurodegeneration. We conducted a further mechanistic investigation into the association of Nur77 with cell death. Cytosporone B (Csn-B), an agonist for Nur77, and Nur77 knockdown were adopted in the 6-hydroxydopamine (OHDA)-lesioned PC12 cells to investigate the mechanisms underlying Nur77-mediated injury. The 6-OHDA incubation caused Nur77 translocation from the nucleus to cytosol and Endoplasm reticulum (ER) and induced co-localization of Tom20/Nur77 and Protein Disulfide Isomerase (PDI)/Nur77. Nur77 activation further decreased cell viability, aggravated intracellular LDH release, intracellular Ca2+, ROS levels, apoptosis, ER tress and, mitochondrial transmembrane potential (ΔΨm) decline. In addition, Nur77 activation significantly enhanced the efficiency of autophagy as indicated by an up-regulation of Beclin-1/LC-3 and downregulation of p62, and aggravated mitochondrial dysfunctions and ER stress as shown by increased HSP60/Cytochrome C (Cyt C) and CHOP-ATF3 levels respectively. These changes could be partially reversed by Nur77 knockdown. Moreover, Nur77 activation upregulated PINK1 and downregulated Parkin levels. We conclude that Nur77 exacerbates PC12 cell death at least partially by aggravating the mitochondrial impairment and ER stress and enhancing autophagy. We propose that Nur77 is likely a critical target in the PD therapy. PMID:27679973

  12. Nafamostat mesilate attenuates transient focal ischemia/reperfusion-induced brain injury via the inhibition of endoplasmic reticulum stress.

    PubMed

    Kwon, Sun Kwan; Ahn, Moonsang; Song, Hee-Jung; Kang, Shin Kwang; Jung, Saet-Byel; Harsha, Nagar; Jee, Sungju; Moon, Jae Young; Suh, Kwang-Sun; Lee, Sang Do; Jeon, Byeong Hwa; Kim, Dong Woon; Kim, Cuk-Seong

    2015-11-19

    Nafamostat mesilate (NM), a serine protease inhibitor, has a broad range of clinical applications that include use as an anticoagulant during hemodialysis in cerebral hemorrhage patients, as a hemoperfusion anticoagulant for patients with intravascular coagulation, hemorrhagic lesions, and hemorrhagic tendencies, and for the improvement of acute pancreatitis. However, the effects of NM on acute cerebral ischemia have yet to be investigated. Thus, the present study utilized a rat model in which transient middle cerebral artery occlusion (MCAO) was used to induce ischemic injury to investigate the effects of NM on infarct volume and histological and biological changes. NM (1mg/kg) was intravenously administered prior to and after the MCAO procedure. Compared to control rats, the administration of NM significantly decreased infarct size and the extent of brain edema after the induction of focal ischemia via MCAO. Additionally, NM treatment attenuated MCAO-induced neuronal degeneration and activation of microglia and astrocytes. NM treatment also inhibited the MCAO-induced expression levels of glucose-regulated protein 78 (GRP78), CATT/EBP homologous protein (CHOP), and p-eukaryotic initiation factor 2α (eIF2α), which are endoplasmic reticulum (ER) stress markers, in the cerebral cortex. The present findings demonstrate that NM exerts neuroprotective effects in the brain following focal ischemia via, at least in part, the inhibition of ER stress.

  13. Endoplasmic reticulum stress-induced apoptosis accompanies enhanced expression of multiple inositol polyphosphate phosphatase 1 (Minpp1): a possible role for Minpp1 in cellular stress response.

    PubMed

    Kilaparty, Surya P; Agarwal, Rakhee; Singh, Pooja; Kannan, Krishnaswamy; Ali, Nawab

    2016-07-01

    Inositol polyphosphates represent a group of differentially phosphorylated inositol metabolites, many of which are implicated to regulate diverse cellular processes such as calcium mobilization, vesicular trafficking, differentiation, apoptosis, etc. The metabolic network of these compounds is complex and tightly regulated by various kinases and phosphatases present predominantly in the cytosol. Multiple inositol polyphosphate phosphatase 1 (Minpp1) is the only known endoplasmic reticulum (ER) luminal enzyme that hydrolyzes various inositol polyphosphates in vitro as well as in vivo conditions. However, access of the Minpp1 to cytosolic substrates has not yet been demonstrated clearly and hence its physiological function. In this study, we examined a potential role for Minpp1 in ER stress-induced apoptosis. We generated a custom antibody and characterized its specificity to study the expression of Minpp1 protein in multiple mammalian cells under experimentally induced cellular stress conditions. Our results demonstrate a significant increase in the expression of Minpp1 in response to a variety of cellular stress conditions. The protein expression was corroborated with the expression of its mRNA and enzymatic activity. Further, in an attempt to link the role of Minpp1 to apoptotic stress, we studied the effect of Minpp1 expression on apoptosis following silencing of the Minpp1 gene by its specific siRNA. Our results suggest an attenuation of apoptotic parameters following knockdown of Minpp1. Thus, in addition to its known role in inositol polyphosphate metabolism, we have identified a novel role for Minpp1 as a stress-responsive protein. In summary, our results provide, for the first time, a probable link between ER stress-induced apoptosis and Minpp1 expression.

  14. Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation.

    PubMed

    Kubota, Kaori; Lee, Daniel H; Tsuchiya, Masahiro; Young, Conan S; Everett, Eric T; Martinez-Mier, Esperanza A; Snead, Malcolm L; Nguyen, Linh; Urano, Fumihiko; Bartlett, John D

    2005-06-17

    The mechanism of how fluoride causes fluorosis remains unknown. Exposure to fluoride can inhibit protein synthesis, and this may also occur by agents that cause endoplasmic reticulum (ER) stress. When translated proteins fail to fold properly or become misfolded, ER stress response genes are induced that together comprise the unfolded protein response. Because ameloblasts are responsible for dental enamel formation, we used an ameloblast-derived cell line (LS8) to characterize specific responses to fluoride treatment. LS8 cells were growth-inhibited by as little as 1.9-3.8 ppm fluoride, whereas higher doses induced ER stress and caspase-mediated DNA fragmentation. Growth arrest and DNA damage-inducible proteins (GADD153/CHOP, GADD45alpha), binding protein (BiP/glucose-responsive protein 78 (GRP78), the non-secreted form of carbonic anhydrase VI (CA-VI), and active X-box-binding protein-1 (Xbp-1) were all induced significantly after exposure to 38 ppm fluoride. Unexpectedly, DNA fragmentation increased when GADD153 expression was inhibited by short interfering RNA treatment but remained unaffected by transient GADD153 overexpression. Analysis of control and GADD153(-/-) embryonic fibroblasts demonstrated that caspase-3 mediated the increased DNA fragmentation observed in the GADD153 null cells. We also demonstrate that mouse incisor ameloblasts are sensitive to the toxic effects of high dose fluoride in drinking water. Activated Ire1 initiates an ER stress response pathway, and mouse ameloblasts were shown to express activated Ire1. Ire1 levels appeared induced by fluoride treatment, indicating that ER stress may play a role in dental fluorosis. Low dose fluoride, such as that present in fluoridated drinking water, did not induce ER stress.

  15. β-Hydroxybutyrate suppresses inflammasome formation by ameliorating endoplasmic reticulum stress via AMPK activation

    PubMed Central

    Park, Min Hi; Lee, Bonggi; Kim, Min Jo; Lee, Eun Kyeong; Chung, Ki Wung; Kim, Seong Min; Im, Dong Soon; Chung, Hae Young

    2016-01-01

    β-Hydroxybutyrate, a ketone body that is used as an energy source in organs such as the brain, muscle, and heart when blood glucose is low, is produced by fatty acid oxidation in the liver under the fasting state. Endoplasmic reticulum (ER) stress is linked with the generation of intracellular reactive oxygen species and the accumulation of misfolded protein in the ER. ER stress is known to induce the NOD-like receptor protein 3 inflammasome, which mediates activation of the proinflammatory cytokine interleukin-1β, whose maturation is caspase-1-dependent. We investigated whether β-hydroxybutyrate modulates ER stress, inflammasome formation, and insulin signaling. Sprague Dawley rats (6 and 24 months of age) that were starved for 3 d and rats treated with β-hydroxybutyrate (200 mg·kg−1·d−1 i.p., for 5 d) were used for in vivo investigations, whereas human hepatoma HepG2 cells were used for in vitro studies. Overexpression of AMPK in cultured cells was performed to elucidate the molecular mechanism. The starvation resulted in increased serum β-hydroxybutyrate levels with decreased ER stress (PERK, IRE1, and ATF6α) and inflammasome (ASC, caspase-1, and NLRP3) formation compared with non-fasted 24-month-old rats. In addition, β-hydroxybutyrate suppressed the increase of ER stress- and inflammasome-related marker proteins. Furthermore, β-hydroxybutyrate treatment increased the expression of manganese superoxide dismutase and catalase via the AMP-activated protein kinase-forkhead box protein O3α transcription factor pathway both in vivo and in vitro. The significance of the current study was the discovery of the potential therapeutic role of β-hydroxybutyrate in suppressing ER-stress-induced inflammasome formation. PMID:27661104

  16. Ablation of PGC1 beta prevents mTOR dependent endoplasmic reticulum stress response

    PubMed Central

    Camacho, Alberto; Rodriguez-Cuenca, Sergio; Blount, Margaret; Prieur, Xavier; Barbarroja, Nuria; Fuller, Maria; Hardingham, Giles E.; Vidal-Puig, Antonio

    2012-01-01

    Mitochondria dysfunction contributes to the pathophysiology of obesity, diabetes, neurodegeneration and ageing. The peroxisome proliferator-activated receptor-gamma coactivator-1β (PGC-1β) coordinates mitochondrial biogenesis and function as well as fatty acid metabolism. It has been suggested that endoplasmic reticulum (ER) stress may be one of the mechanisms linking mitochondrial dysfunction and these pathologies. Here we investigate whether PGC-1β ablation affects the ER stress response induced by specific nutritional and pharmacological challenges in the CNS. By using flow cytometry, western blot, real time PCR and several pharmacological and nutritional interventions in PGC-1β knock out and WT mice, we confirmed that PGC-1β coordinates mitochondria function in brain and reported for the first time that a) ablation of PGC-1β is associated with constitutive activation of mTORC1 pathway associated with increased basal GRP78 protein levels in hypothalamus and cortex of animals fed chow diet; and b) in animals fed chronically with high fat diet (HFD) or high protein diet (HPD), we observed a failure to appropriately induce ER stress response in the absence of PGC-1β, associated with an increase in mTOR pathway phosphorylation. This contrasted with the appropriate upregulation of ER stress response observed in wild type littermates. Additionally, inefficient in vitro induction of ER stress by thapsigargin seems result in apoptotic neuronal cell death in PGC-1β KO. Our data indicate that PGC-1β is required for a neuronal ER response to nutritional stress imposed by HFD and HPD diets and that genetic ablation of PGC-1β might increase the susceptibility to neuronal damage and cell death. PMID:22771762

  17. Interferon alpha impairs insulin production in human beta cells via endoplasmic reticulum stress.

    PubMed

    Lombardi, Angela; Tomer, Yaron

    2017-02-23

    Despite substantial advances in the research exploring the pathogenesis of Type 1 Diabetes (T1D), the pathophysiological mechanisms involved remain unknown. We hypothesized in this study that interferon alpha (IFNα) participates in the early stages of T1D development by triggering endoplasmic reticulum (ER) stress. To verify our hypothesis, human islets and human EndoC-βH1 cells were exposed to IFNα and tested for ER stress markers, glucose stimulated insulin secretion (GSIS) and insulin content. IFNα treatment induced upregulation of ER stress markers including Binding immunoglobulin Protein, phospho-eukaryotic translation initiation factor 2α, spliced- X-box binding protein-1, C/EBP homologous protein and activating transcription factor 4. Intriguingly, IFNα treatment did not impair GSIS but significantly decreased insulin production in both human islets and EndoC-βH1 cells. Furthermore, IFNα decreased the expression of both proinsulin convertase 1 and proinsulin convertase 2, suggesting an altered functional state of the beta cells characterized by a slower proinsulin-insulin conversion. Pretreatment of both human islets and EndoC-βH1 cells with chemical chaperones 4-phenylbutyric acid and tauroursodeoxycholic acid completely prevented IFNα effects, indicating an ER stress-mediated impairment of insulin production. We demonstrated for the first time that IFNα elicits ER stress in human beta cells providing a novel mechanistic role for this virus-induced cytokine in the development of T1D. Compounds targeting molecular processes altered in ER-stressed beta cells could represent a potential therapeutic strategy to prevent IFNα-induced beta cell dysfunction in the early onset of T1D.

  18. Atorvastatin attenuates atherosclerotic plaque destabilization by inhibiting endoplasmic reticulum stress in hyperhomocysteinemic mice.

    PubMed

    Jia, Fang; Wu, Chunfang; Chen, Zhenyue; Lu, Guoping; Sun, Jianhui

    2016-04-01

    Endoplasmic reticulum (ER) stress has been suggested to play a role in the progression of plaque vulnerability and the occurrence of acute complications of coronary atherosclerosis. Atorvastatin is known to exert pleiotropic effects on the cardiovascular system. The present study aimed to examine the stabilizing effects of atorvastatin on vulnerable plaques within hyperhomocysteinemic apolipoprotein E‑deficient (ApoE‑/‑) mice, and to investigate the potential mechanisms underlying ER stress in ApoE‑/‑ mice and macrophages. In the present study, ApoE‑/‑ mice were administrated methionine or atorvastatin, and were sacrificed after 2 months. Necrotic core size, collagen content and inflammatory cytokine infiltration were subsequently measured in the aortic lesions, in order to investigate plaque stability. Treatment with atorvastatin decreased the number and size of necrotic cores, increased collagen content, and downregulated tumor necrosis factor (TNF)‑α and matrix metalloproteinase (MMP)‑9 mRNA expression, as compared with the methionine group. Immunohistochemical analysis indicated that atorvastatin administration prevented ER stress activation in aortic lesions of hyperhomocysteinemic mice. Furthermore, macrophages were challenged with homocysteine (Hcy) in the presence or absence of atorvastatin and thapsigargin (an ER stress inducer). Atorvastatin suppressed Hcy‑induced ER stress, and downregulated TNF‑α and MMP‑9 mRNA expression in the macrophages. Conversely, thapsigargin attenuated the inhibitory effects of atorvastatin against Hcy‑induced TNF‑α and MMP‑9 expression. These results indicated that hyperhomocysteinemia may promote atherosclerotic plaque development and instability. In addition, atorvastatin was able to improve atherosclerotic plaque stability in hyperhomocysteinemic mice by inhibiting ER stress.

  19. HMGB1 induces an inflammatory response in endothelial cells via the RAGE-dependent endoplasmic reticulum stress pathway

    SciTech Connect

    Luo, Ying; Li, Shu-Jun; Yang, Jian; Qiu, Yuan-Zhen; Chen, Fang-Ping

    2013-09-06

    Highlights: •Mechanisms of inflammatory response induced by HMGB1 are incompletely understood. •We found that endoplasmic reticulum stress mediate the inflammatory response induced by HMGB1. •RAGE-mediated ERS pathways are involved in those processes. •We reported a new mechanism for HMGB1 induced inflammatory response. -- Abstract: The high mobility group 1B protein (HMGB1) mediates chronic inflammatory responses in endothelial cells, which play a critical role in atherosclerosis. However, the underlying mechanism is unknown. The goal of our study was to identify the effects of HMGB1 on the RAGE-induced inflammatory response in endothelial cells and test the possible involvement of the endoplasmic reticulum stress pathway. Our results showed that incubation of endothelial cells with HMGB1 (0.01–1 μg/ml) for 24 h induced a dose-dependent activation of endoplasmic reticulum stress transducers, as assessed by PERK and IRE1 protein expression. Moreover, HMGB1 also promoted nuclear translocation of ATF6. HMGB1-mediated ICAM-1 and P-selectin production was dramatically suppressed by PERK siRNA or IRE1 siRNA. However, non-targeting siRNA had no such effects. HMGB1-induced increases in ICAM-1 and P-selectin expression were also inhibited by a specific eIF2α inhibitor (salubrinal) and a specific JNK inhibitor (SP600125). Importantly, a blocking antibody specifically targeted against RAGE (anti-RAGE antibody) decreased ICAM-1, P-selectin and endoplasmic reticulum stress molecule (PERK, eIF2α, IRE1 and JNK) protein expression levels. Collectively, these novel findings suggest that HMGB1 promotes an inflammatory response by inducing the expression of ICAM-1 and P-selectin via RAGE-mediated stimulation of the endoplasmic reticulum stress pathway.

  20. Homocysteine-induced endoplasmic reticulum stress causes dysregulation of the cholesterol and triglyceride biosynthetic pathways

    PubMed Central

    Werstuck, Geoff H.; Lentz, Steven R.; Dayal, Sanjana; Hossain, Gazi S.; Sood, Sudesh K.; Shi, Yuan Y.; Zhou, Ji; Maeda, Nobuyo; Krisans, Skaidrite K.; Malinow, M. Rene; Austin, Richard C.

    2001-01-01

    Hepatic steatosis is common in patients having severe hyperhomocysteinemia due to deficiency for cystathionine β-synthase. However, the mechanism by which homocysteine promotes the development and progression of hepatic steatosis is unknown. We report here that homocysteine-induced endoplasmic reticulum (ER) stress activates both the unfolded protein response and the sterol regulatory element–binding proteins (SREBPs) in cultured human hepatocytes as well as vascular endothelial and aortic smooth muscle cells. Activation of the SREBPs is associated with increased expression of genes responsible for cholesterol/triglyceride biosynthesis and uptake and with intracellular accumulation of cholesterol. Homocysteine-induced gene expression was inhibited by overexpression of the ER chaperone, GRP78/BiP, thus demonstrating a direct role of ER stress in the activation of cholesterol/triglyceride biosynthesis. Consistent with these in vitro findings, cholesterol and triglycerides were significantly elevated in the livers, but not plasmas, of mice having diet-induced hyperhomocysteinemia. This effect was not due to impaired hepatic export of lipids because secretion of VLDL-triglyceride was increased in hyperhomocysteinemic mice. These findings suggest a mechanism by which homocysteine-induced ER stress causes dysregulation of the endogenous sterol response pathway, leading to increased hepatic biosynthesis and uptake of cholesterol and triglycerides. Furthermore, this mechanism likely explains the development and progression of hepatic steatosis and possibly atherosclerotic lesions observed in hyperhomocysteinemia. PMID:11375416

  1. Baicalein Induces Apoptosis and Autophagy via Endoplasmic Reticulum Stress in Hepatocellular Carcinoma Cells

    PubMed Central

    Jiang, Chunping; Luo, Dongjun; Cao, Yin; Liu, Baorui

    2014-01-01

    Background. Hepatocellular carcinoma (HCC) remains a disastrous disease and the treatment for HCC is rather limited. Separation and identification of active compounds from traditionally used herbs in HCC treatment may shed light on novel therapeutic drugs for HCC. Methods. Cell viability and colony forming assay were conducted to determine anti-HCC activity. Morphology of cells and activity of caspases were analyzed. Antiapoptotic Bcl-2 family proteins and JNK were also examined. Levels of unfolded protein response (UPR) markers were determined and intracellular calcium was assayed. Small interfering RNAs (siRNAs) were used to investigate the role of UPR and autophagy in baicalein-induced cell death. Results. Among four studied flavonoids, only baicalein exhibited satisfactory inhibition of viability and colony formation of HCC cells within water-soluble concentration. Baicalein induced apoptosis via endoplasmic reticulum (ER) stress, possibly by downregulating prosurvival Bcl-2 family, increasing intracellular calcium, and activating JNK. CHOP was the executor of cell death during baicalein-induced ER stress while eIF2α and IRE1α played protective roles. Protective autophagy was also triggered by baicalein in HCC cells. Conclusion. Baicalein exhibits prominent anti-HCC activity. This flavonoid induces apoptosis and protective autophagy via ER stress. Combination of baicalein and autophagy inhibitors may represent a promising therapy against HCC. PMID:24995326

  2. Protective effect of mild endoplasmic reticulum stress on radiation-induced bystander effects in hepatocyte cells.

    PubMed

    Xie, Yuexia; Ye, Shuang; Zhang, Jianghong; He, Mingyuan; Dong, Chen; Tu, Wenzhi; Liu, Peifeng; Shao, Chunlin

    2016-12-13

    Radiation-induced bystander effect (RIBE) has important implications for secondary cancer risk assessment during cancer radiotherapy, but the defense and self-protective mechanisms of bystander normal cells are still largely unclear. The present study found that micronuclei (MN) formation could be induced in the non-irradiated HL-7702 hepatocyte cells after being treated with the conditioned medium from irradiated hepatoma HepG2 cells under either normoxia or hypoxia, where the ratio of the yield of bystander MN induction to the yield of radiation-induced MN formation under hypoxia was much higher than that of normoxia. Nonetheless, thapsigargin induced endoplasmic reticulum (ER) stress and dramatically suppressed this bystander response manifested as the decrease of MN and apoptosis inductions. Meanwhile, the interference of BiP gene, a major ER chaperone, amplified the detrimental RIBE. More precisely, thapsigargin provoked ER sensor of PERK to initiate an instantaneous and moderate ER stress thus defensed the hazard form RIBE, while BiP depletion lead to persistently destroyed homeostasis of ER and exacerbated cell injury. These findings provide new insights that the mild ER stress through BiP-PERK-p-eIF2α signaling pathway has a profound role in protecting cellular damage from RIBE and hence may decrease the potential secondary cancer risk after cancer radiotherapy.

  3. Endoplasmic reticulum stress in amelogenesis imperfecta and phenotypic rescue using 4-phenylbutyrate

    PubMed Central

    Brookes, Steven J.; Barron, Martin J.; Boot-Handford, Ray; Kirkham, Jennifer; Dixon, Michael J.

    2014-01-01

    Inherited diseases caused by genetic mutations can arise due to loss of protein function. Alternatively, mutated proteins may mis-fold, impairing endoplasmic reticulum (ER) trafficking, causing ER stress and triggering the unfolded protein response (UPR). The UPR attempts to restore proteostasis but if unsuccessful drives affected cells towards apoptosis. Previously, we reported that in mice, the p.Tyr64His mutation in the enamel extracellular matrix (EEM) protein amelogenin disrupts the secretory pathway in the enamel-forming ameloblasts, resulting in eruption of malformed tooth enamel that phenocopies human amelogenesis imperfecta (AI). Defective amelogenin post-secretory self-assembly and processing within the developing EEM has been suggested to underlie the pathogenesis of X chromosome-linked AI. Here, we challenge this concept by showing that AI pathogenesis associated with the p.Tyr64His amelogenin mutation involves ameloblast apoptosis induced by ER stress. Furthermore, we show that 4-phenylbutyrate can rescue the enamel phenotype in affected female mice by promoting cell survival over apoptosis such that they are able to complete enamel formation despite the presence of the mutation, offering a potential therapeutic option for patients with this form of AI and emphasizing the importance of ER stress in the pathogenesis of this inherited conformational disease. PMID:24362885

  4. Z α-1 antitrypsin deficiency and the endoplasmic reticulum stress response

    PubMed Central

    Greene, Catherine M; McElvaney, Noel G

    2010-01-01

    The serine proteinase inhibitor α-1 antitrypsin (AAT) is produced principally by the liver at the rate of 2 g/d. It is secreted into the circulation and provides an antiprotease protective screen throughout the body but most importantly in the lung, where it can neutralise the activity of the serine protease neutrophil elastase. Mutations leading to deficiency in AAT are associated with liver and lung disease. The most notable is the Z AAT mutation, which encodes a misfolded variant of the AAT protein in which the glutamic acid at position 342 is replaced by a lysine. More than 95% of all individuals with AAT deficiency carry at least one Z allele. ZAAT protein is not secreted effectively and accumulates intracellularly in the endoplasmic reticulum (ER) of hepatocytes and other AAT-producing cells. This results in a loss of function associated with decreased circulating and intrapulmonary levels of AAT. However, the misfolded protein acquires a toxic gain of function that impacts on the ER. A major function of the ER is to ensure correct protein folding. ZAAT interferes with this function and promotes ER stress responses and inflammation. Here the signalling pathways activated during ER stress in response to accumulation of ZAAT are described and therapeutic strategies that can potentially relieve ER stress are discussed. PMID:21577302

  5. Emergence of endoplasmic reticulum stress and activated microglia in Purkinje cell degeneration mice.

    PubMed

    Kyuhou, Shin-ichi; Kato, Nobuo; Gemba, Hisae

    2006-03-27

    In the current studies, we characterized the molecular and cellular mechanism of cell death in Purkinje cell degeneration (pcd) mice using real-time quantitative PCR, immunohistochemistry, and Western blotting. It appears that endoplasmic reticulum (ER) stress is involved in this degeneration of Purkinje cells because ER stress-related substrates, such as CHOP and caspase 12, were strongly activated in Purkinje cells of pcd mice during the third postnatal (P) week. A significant increase in the expression of the ER-specific chaperone BiP suggested that unfolded protein responses were induced. We also found that Purkinje cells underwent apoptosis via the activation of caspase 3 and subsequent fragmentation of DNA. In addition to the activation of apoptosis in Purkinje cells, many activated microglial cells are found to be present in the molecular layer of the cerebellar cortex. In the later phase of degeneration, there was conspicuous expression of inducible nitric oxide synthase (iNOS), and some Purkinje cells were strongly labeled with an antibody to nitrotyrosine, suggesting that Purkinje cells in pcd mice are damaged by nitric oxide released from microglial cells. Administration of minocycline, which may inhibit iNOS expression, delayed the death of Purkinje cells in pcd mice and mildly improved their motor abilities. These findings suggest that ER stress participates in the degeneration of Purkinje cells and that activation of microglia accelerates Purkinje cell death in pcd mice.

  6. Endoplasmic Reticulum Oxidative Stress Triggers Tgf-Beta-Dependent Muscle Dysfunction by Accelerating Ascorbic Acid Turnover

    PubMed Central

    Pozzer, Diego; Favellato, Mariagrazia; Bolis, Marco; Invernizzi, Roberto William; Solagna, Francesca; Blaauw, Bert; Zito, Ester

    2017-01-01

    Endoplasmic reticulum (ER) and oxidative stress are two related phenomena that have important metabolic consequences. As many skeletal muscle diseases are triggered by oxidative stress, we explored the chain of events linking a hyperoxidized ER (which causes ER and oxidative stress) with skeletal muscle dysfunction. An unbiased exon expression array showed that the combined genetic modulation of the two master ER redox proteins, selenoprotein N (SEPN1) and endoplasmic oxidoreductin 1 (ERO1), led to an SEPN1-related myopathic phenotype due to excessive signalling of transforming growth factor (TGF)-beta. The increased TGF-beta activity in the genetic mutants was caused by accelerated turnover of the ER localized (anti-oxidant) ascorbic acid that affected collagen deposition in the extracellular matrix. In a mouse mutant of SEPN1, which is dependent on exogenous ascorbic acid, a limited intake of ascorbic acid revealed a myopathic phenotype as a consequence of an altered TGF-beta signalling. Indeed, systemic antagonism of TGF-beta re-established skeletal muscle function in SEPN1 mutant mice. In conclusion, this study sheds new light on the molecular mechanism of SEPN1-related myopathies and indicates that the TGF-beta/ERO1/ascorbic acid axis offers potential for their treatment. PMID:28106121

  7. Berberine prevents progression from hepatic steatosis to steatohepatitis and fibrosis by reducing endoplasmic reticulum stress

    PubMed Central

    Zhang, Zhiguo; Li, Bo; Meng, Xiangjian; Yao, Shuangshuang; Jin, Lina; Yang, Jian; Wang, Jiqiu; Zhang, Huizhi; Zhang, Zhijian; Cai, Dongsheng; Zhang, Yifei; Ning, Guang

    2016-01-01

    The histological spectrum of nonalcoholic fatty liver diseases (NAFLD) ranges from hepatic steatosis to steatohepatitis and fibrosis. Berberine (BBR) is known for its therapeutic effect on obesity, hyperglycaemia and dyslipidaemia; however, its effect on NAFLD has yet to be thoroughly explored. Db/db mice and methionine-choline-deficient diet-fed mice were administered BBR via gavage. We found that BBR-treated mice were more resistant to steatosis in the liver than vehicle-treated mice and that BBR significantly reduced hepatic inflammation, fibrosis and lipid peroxides. The beneficial effect of BBR was associated with suppressing endoplasmic reticulum (ER) stress. Additionally, BBR decreased the free fatty acid-induced lipid accumulation and tunicamycin-induced ER stress in primary hepatocytes and hepatocyte cell lines. We demonstrated that BBR exhibited chaperone activity, reduced protein aggregation in vitro and alleviated tunicamycin-induced triglyceride and collagen deposition in vivo. Finally, we showed that BBR could reverse ER stress-activated lipogenesis through the ATF6/SREBP-1c pathway in vitro. These results indicated that BBR may be a new therapeutic strategy against hepatic steatosis and non-alcoholic steatohepatitis. PMID:26857750

  8. Trichodermin induces cell apoptosis through mitochondrial dysfunction and endoplasmic reticulum stress in human chondrosarcoma cells

    SciTech Connect

    Su, Chen-Ming; Wang, Shih-Wei; Lee, Tzong-Huei; Tzeng, Wen-Pei; Hsiao, Che-Jen; Liu, Shih-Chia; Tang, Chih-Hsin

    2013-10-15

    Chondrosarcoma is the second most common primary bone tumor, and it responds poorly to both chemotherapy and radiation treatment. Nalanthamala psidii was described originally as Myxosporium in 1926. This is the first study to investigate the anti-tumor activity of trichodermin (trichothec-9-en-4-ol, 12,13-epoxy-, acetate), an endophytic fungal metabolite from N. psidii against human chondrosarcoma cells. We demonstrated that trichodermin induced cell apoptosis in human chondrosarcoma cell lines (JJ012 and SW1353 cells) instead of primary chondrocytes. In addition, trichodermin triggered endoplasmic reticulum (ER) stress protein levels of IRE1, p-PERK, GRP78, and GRP94, which were characterized by changes in cytosolic calcium levels. Furthermore, trichodermin induced the upregulation of Bax and Bid, the downregulation of Bcl-2, and the dysfunction of mitochondria, which released cytochrome c and activated caspase-3 in human chondrosarcoma. In addition, animal experiments illustrated reduced tumor volume, which led to an increased number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells and an increased level of cleaved PARP protein following trichodermin treatment. Together, this study demonstrates that trichodermin is a novel anti-tumor agent against human chondrosarcoma cells both in vitro and in vivo via mitochondrial dysfunction and ER stress. - Highlights: • Trichodermin induces chondrosarcoma apoptosis. • ER stress is involved in trichodermin-induced cell death. • Trichodermin induces chondrosarcoma death in vivo.

  9. Endoplasmic reticulum stress in amelogenesis imperfecta and phenotypic rescue using 4-phenylbutyrate.

    PubMed

    Brookes, Steven J; Barron, Martin J; Boot-Handford, Ray; Kirkham, Jennifer; Dixon, Michael J

    2014-05-01

    Inherited diseases caused by genetic mutations can arise due to loss of protein function. Alternatively, mutated proteins may mis-fold, impairing endoplasmic reticulum (ER) trafficking, causing ER stress and triggering the unfolded protein response (UPR). The UPR attempts to restore proteostasis but if unsuccessful drives affected cells towards apoptosis. Previously, we reported that in mice, the p.Tyr64His mutation in the enamel extracellular matrix (EEM) protein amelogenin disrupts the secretory pathway in the enamel-forming ameloblasts, resulting in eruption of malformed tooth enamel that phenocopies human amelogenesis imperfecta (AI). Defective amelogenin post-secretory self-assembly and processing within the developing EEM has been suggested to underlie the pathogenesis of X chromosome-linked AI. Here, we challenge this concept by showing that AI pathogenesis associated with the p.Tyr64His amelogenin mutation involves ameloblast apoptosis induced by ER stress. Furthermore, we show that 4-phenylbutyrate can rescue the enamel phenotype in affected female mice by promoting cell survival over apoptosis such that they are able to complete enamel formation despite the presence of the mutation, offering a potential therapeutic option for patients with this form of AI and emphasizing the importance of ER stress in the pathogenesis of this inherited conformational disease.

  10. Reactive Oxygen Species, Endoplasmic Reticulum Stress and Mitochondrial Dysfunction: The Link with Cardiac Arrhythmogenesis

    PubMed Central

    Tse, Gary; Yan, Bryan P.; Chan, Yin W. F.; Tian, Xiao Yu; Huang, Yu

    2016-01-01

    Background: Cardiac arrhythmias represent a significant problem globally, leading to cerebrovascular accidents, myocardial infarction, and sudden cardiac death. There is increasing evidence to suggest that increased oxidative stress from reactive oxygen species (ROS), which is elevated in conditions such as diabetes and hypertension, can lead to arrhythmogenesis. Method: A literature review was undertaken to screen for articles that investigated the effects of ROS on cardiac ion channel function, remodeling and arrhythmogenesis. Results: Prolonged endoplasmic reticulum stress is observed in heart failure, leading to increased production of ROS. Mitochondrial ROS, which is elevated in diabetes and hypertension, can stimulate its own production in a positive feedback loop, termed ROS-induced ROS release. Together with activation of mitochondrial inner membrane anion channels, it leads to mitochondrial depolarization. Abnormal function of these organelles can then activate downstream signaling pathways, ultimately culminating in altered function or expression of cardiac ion channels responsible for generating the cardiac action potential (AP). Vascular and cardiac endothelial cells become dysfunctional, leading to altered paracrine signaling to influence the electrophysiology of adjacent cardiomyocytes. All of these changes can in turn produce abnormalities in AP repolarization or conduction, thereby increasing likelihood of triggered activity and reentry. Conclusion: ROS plays a significant role in producing arrhythmic substrate. Therapeutic strategies targeting upstream events include production of a strong reducing environment or the use of pharmacological agents that target organelle-specific proteins and ion channels. These may relieve oxidative stress and in turn prevent arrhythmic complications in patients with diabetes, hypertension, and heart failure. PMID:27536244

  11. Protective effect of mild endoplasmic reticulum stress on radiation-induced bystander effects in hepatocyte cells

    PubMed Central

    Xie, Yuexia; Ye, Shuang; Zhang, Jianghong; He, Mingyuan; Dong, Chen; Tu, Wenzhi; Liu, Peifeng; Shao, Chunlin

    2016-01-01

    Radiation-induced bystander effect (RIBE) has important implications for secondary cancer risk assessment during cancer radiotherapy, but the defense and self-protective mechanisms of bystander normal cells are still largely unclear. The present study found that micronuclei (MN) formation could be induced in the non-irradiated HL-7702 hepatocyte cells after being treated with the conditioned medium from irradiated hepatoma HepG2 cells under either normoxia or hypoxia, where the ratio of the yield of bystander MN induction to the yield of radiation-induced MN formation under hypoxia was much higher than that of normoxia. Nonetheless, thapsigargin induced endoplasmic reticulum (ER) stress and dramatically suppressed this bystander response manifested as the decrease of MN and apoptosis inductions. Meanwhile, the interference of BiP gene, a major ER chaperone, amplified the detrimental RIBE. More precisely, thapsigargin provoked ER sensor of PERK to initiate an instantaneous and moderate ER stress thus defensed the hazard form RIBE, while BiP depletion lead to persistently destroyed homeostasis of ER and exacerbated cell injury. These findings provide new insights that the mild ER stress through BiP-PERK-p-eIF2α signaling pathway has a profound role in protecting cellular damage from RIBE and hence may decrease the potential secondary cancer risk after cancer radiotherapy. PMID:27958308

  12. Combined inhibition of Hsp90 and heme oxygenase-1 induces apoptosis and endoplasmic reticulum stress in melanoma.

    PubMed

    Barbagallo, Ignazio; Parenti, Rosalba; Zappalà, Agata; Vanella, Luca; Tibullo, Daniele; Pepe, Francesco; Onni, Toniangelo; Li Volti, Giovanni

    2015-10-01

    Heat shock proteins are ubiquitous molecular chaperones involved in post-translational folding, stability, activation and maturation of many proteins that are essential mediators of signal transduction and cell cycle progression. Heat shock protein 90 (Hsp90) has recently emerged as an attractive therapeutic target in cancer treatment since it may act as a key regulator of various oncogene products and cell-signaling molecules. Heme oxygenase-1 (HO-1; also known as Hsp32) is an inducible enzyme participating in heme degradation and involved in oxidative stress resistance. Recent studies indicate that HO-1 activation may play a role in tumor development and progression. In the present study we investigated the chemotherapic effects of combining an Hsp90 inhibitor (NMS E973) and an HO-1 inhibitor (SnMP) on A375 melanoma cells. NMS E973 treatment was able to reduce cell viability and induce endoplasmic reticulum (ER) stress (i.e. Ire1α, ERO1, PDI, BIP and CHOP). Interestingly, no significant effect was observed in reactive oxygen species (ROS) formation. Finally, NMS E973 treatment resulted in a significant HO-1 overexpression, which in turn serves as a possible chemoresistance molecular mechanism. Interestingly, the combination of NMS E973 and SnMP produced an increase of ROS and reduced cell viability compared to NMS E973 treatment alone. The inhibitors combination exhibited higher ER stress, apoptosis as evidenced by bifunctional apoptosis regulator (BFAR) mRNA expression and lower phosphorylation of Akt when compared to NMS E973 alone. In conclusion, these data suggest that HO-1 inhibition potentiates NMS E973 toxicity and may be exploited as a strategy for melanoma treatment.

  13. VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation.

    PubMed

    Shih, Yu-Tzu; Hsueh, Yi-Ping

    2016-03-17

    Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders.

  14. VCP and ATL1 regulate endoplasmic reticulum and protein synthesis for dendritic spine formation

    PubMed Central

    Shih, Yu-Tzu; Hsueh, Yi-Ping

    2016-01-01

    Imbalanced protein homeostasis, such as excessive protein synthesis and protein aggregation, is a pathogenic hallmark of a range of neurological disorders. Here, using expression of mutant proteins, a knockdown approach and disease mutation knockin mice, we show that VCP (valosin-containing protein), together with its cofactor P47 and the endoplasmic reticulum (ER) morphology regulator ATL1 (Atlastin-1), regulates tubular ER formation and influences the efficiency of protein synthesis to control dendritic spine formation in neurons. Strengthening the significance of protein synthesis in dendritic spinogenesis, the translation blocker cyclohexamide and the mTOR inhibitor rapamycin reduce dendritic spine density, while a leucine supplement that increases protein synthesis ameliorates the dendritic spine defects caused by Vcp and Atl1 deficiencies. Because VCP and ATL1 are the causative genes of several neurodegenerative and neurodevelopmental disorders, we suggest that impaired ER formation and inefficient protein synthesis are significant in the pathogenesis of multiple neurological disorders. PMID:26984393

  15. Smoke exposure causes endoplasmic reticulum stress and lipid accumulation in retinal pigment epithelium through oxidative stress and complement activation.

    PubMed

    Kunchithapautham, Kannan; Atkinson, Carl; Rohrer, Bärbel

    2014-05-23

    Age-related macular degeneration (AMD) is a complex disease caused by genetic and environmental factors, including genetic variants in complement components and smoking. Smoke exposure leads to oxidative stress, complement activation, endoplasmic reticulum (ER) stress, and lipid dysregulation, which have all been proposed to be associated with AMD pathogenesis. Here we examine the effects of smoke exposure on the retinal pigment epithelium (RPE). Mice were exposed to cigarette smoke or filtered air for 6 months. RPE cells grown as stable monolayers were exposed to 5% cigarette smoke extract (CSE). Effects of smoke were determined by biochemical, molecular, and histological measures. Effects of the alternative pathway (AP) of complement and complement C3a anaphylatoxin receptor signaling were analyzed using knock-out mice or specific inhibitors. ER stress markers were elevated after smoke exposure in RPE of intact mice, which was eliminated in AP-deficient mice. To examine this relationship further, RPE monolayers were exposed to CSE. Short term smoke exposure resulted in production and release of complement C3, the generation of C3a, oxidative stress, complement activation on the cell membrane, and ER stress. Long term exposure to CSE resulted in lipid accumulation, and secretion. All measures were reversed by blocking C3a complement receptor (C3aR), alternative complement pathway signaling, and antioxidant therapy. Taken together, our results provide clear evidence that smoke exposure results in oxidative stress and complement activation via the AP, resulting in ER stress-mediated lipid accumulation, and further suggesting that oxidative stress and complement act synergistically in the pathogenesis of AMD.

  16. Endoplasmic reticulum stress and Nrf2 repression in circulating cells of type 2 diabetic patients without the recommended glycemic goals.

    PubMed

    Mozzini, C; Garbin, U; Stranieri, C; Pasini, A; Solani, E; Tinelli, I A; Cominacini, L; Fratta Pasini, A M

    2015-03-01

    Endoplasmic reticulum (ER) stress plays a role in the pathogenesis of type 2 diabetes mellitus (T2DM), with activation of the unfolded protein response (UPR) and ER apoptosis in β-cells. The aim of the study is investigating the role of the prolonged glycemic, inflammatory, and oxidative impairment as possible UPR and ER apoptosis inductors in triggering the ER stress response and the protective nuclear erythroid-related factor 2 (Nrf2)/antioxidant-related element (ARE) activation in peripheral blood mononuclear cells (PBMC) of T2DM patients without glycemic target. Oxidative stress markers (oxidation product of phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine [oxPAPC], and malondialdehyde [MDA]), the UPR and ER apoptosis, the activation of the pro-inflammatory nuclear factor-kappa B (NF-kB) with its inhibitory protein inhibitor-kBα, and the expression of the protective Nrf2 and heme oxygenase-1 (HO-1) were evaluated in PBMC of 15 T2DM patients and 15 healthy controls (C). OxPAPC concentrations (in PBMC and plasma), MDA levels (in plasma), the expressions of the glucose-regulated protein 78 kDa (or BiP) as representative of UPR, and of the CCAAT/enhancer-binding protein homologous protein as representative of ER apoptosis were significantly higher (p < 0.01) in T2DM with respect to C. IkBα expression was significantly lower (p < 0.01) in T2DM as well as Nrf2 and HO-1. In vitro experiments demonstrated that hyperglycemic conditions, if prolonged, were NF-kB inductors, without a corresponding Nrf2/ARE response. In PBMC of T2DM without glycemic target achievement, there is an activation of the UPR and of the ER apoptosis, which may be related to the chronic exposure to hyperglycemia, to the augmented inflammation, and to the augmented oxidative stress, without a corresponding Nrf2/ARE defense activation.

  17. Cold-inducible RBM3 inhibits PERK phosphorylation through cooperation with NF90 to protect cells from endoplasmic reticulum stress.

    PubMed

    Zhu, Xinzhou; Zelmer, Andrea; Kapfhammer, Josef P; Wellmann, Sven

    2016-02-01

    The cold-inducible RNA-binding motif protein 3 (RBM3) is involved in the protection of neurons in hypoxic-ischemic and neurodegenerative disorders. RBM3 belongs to a small group of proteins whose synthesis increases during hypothermia while global protein production is slowed down. To investigate the molecular mechanisms underlying RBM3 action, we subjected hippocampal organotypic slice cultures from RBM3 knockout mice to various stressors and found exuberant signaling of the endoplasmic reticulum (ER) stress pathway PRKR-like ER kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α)-CCAAT/enhancer-binding protein homologous protein (CHOP) as compared with wild-type mice. Further, blocking RBM3 expression in human embryonic kidney HEK293 cells by specific small interfering RNAs increased phosphorylation of PERK and eIF2α, whereas overexpression of RBM3 prevented PERK-eIF2α-CHOP signaling during ER stress induced by thapsigargin or tunicamycin. RBM3 did not affect expression of the ER stress sensor immunoglobulin binding protein/GRP78. However, based on affinity purification coupled with mass spectrometry, coimmunoprecipitation, and proximity ligation assay, we revealed that nuclear factor 90 (NF90) is a novel protein interactor of PERK and that this interaction is essential for RBM3-mediated regulation of PERK activity, which requires an RNA-dependent interaction. In conclusion, our data provide evidence for a central role of RBM3 in preventing cell death by inhibiting the PERK-eIF2α-CHOP ER stress pathway through cooperation with NF90.

  18. Fisetin induces apoptosis and endoplasmic reticulum stress in human non-small cell lung cancer through inhibition of the MAPK signaling pathway.

    PubMed

    Kang, Kyoung Ah; Piao, Mei Jing; Madduma Hewage, Susara Ruwan Kumara; Ryu, Yea Seong; Oh, Min Chang; Kwon, Taeg Kyu; Chae, Sungwook; Hyun, Jin Won

    2016-07-01

    Fisetin (3,3',4',7-tetrahydroxyflavone), a dietary flavonoid compound, is currently being investigated for its anticancer effect in various cancer models, including lung cancer. Recent studies show that fisetin induces cell growth inhibition and apoptosis in the human non-small cell lung cancer line NCI-H460. In this study, we investigated whether fisetin can induce endoplasmic reticulum (ER) stress-mediated apoptosis in NCI-H460 cells. Fisetin induced mitochondrial reactive oxygen species (ROS) and characteristic signs of ER stress: ER staining; mitochondrial Ca(2+) overload; expression of ER stress-related proteins; glucose-regulated protein (GRP)-78, phosphorylation of protein kinase RNA (PKR)-like endoplasmic reticulum kinase (PERK) and phosphorylation of eukaryotic initiation factor-2 α subunit; cleavage of activating transcription factor-6; phosphorylation of inositol-requiring kinase-1 and splicing of X-box transcription factor-1; induction of C/EBP homologous protein and cleaved caspase-12. siRNA-mediated knockdown of CHOP and ATF-6 attenuated fisetin-induced apoptotic cell death. In addition, fisetin induced phosphorylation of ERK, JNK, and p38 MAPK. Moreover, silencing of the MAPK signaling pathway prevented apoptotic cell death. In summary, our results indicate that, in NCI-H460 cells, fisetin induces apoptosis and ER stress that is mediated by induction of the MAPK signaling pathway.

  19. Ammonia exposure induces oxidative stress, endoplasmic reticulum stress and apoptosis in hepatopancreas of pacific white shrimp (Litopenaeus vannamei).

    PubMed

    Liang, Zhongxiu; Liu, Rui; Zhao, Depeng; Wang, Lingling; Sun, Mingzhe; Wang, Mengqiang; Song, Linsheng

    2016-07-01

    Ammonia is one of major environmental pollutants in the aquatic system that poses a great threat to the survival of shrimp. In the present study, the mRNA expression of endoplasmic reticulum (ER) stress marker and unfolded protein response (UPR) related genes, as well as the change of redox enzyme and apoptosis were investigated in hepatopancreas of the pacific white shrimp, Litopenaeus vannamei after the exposure of 20 mg L(-1) total ammonia nitrogen (TAN). Compared with the control group, the superoxide dismutase (SOD) activity in hepatopancreas decreased significantly (p < 0.05) at 96 h, whereas the malonyldialdehyde (MDA) concentration increased significantly (p < 0.05). The mRNA expression levels of ER stress marker-immunoglobulin heavy chain binding protein (Bip) gene and key UPR related genes including activating transcription factor 4 (ATF4) and the spliced form of X box binding protein 1 (XBP1) increased significantly (p < 0.05) in hepatopancreas at 96 h after exposure to ammonia. In addition, apoptosis was observed obviously in the hepatopancreas of L. vannamei after exposure to ammonia by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The results indicated that ammonia exposure could induce oxidative stress, which further caused ER stress and apoptosis in hepatopancreas of L. vannamei.

  20. The Effect of Chronic Ozone Exposure on the Activation of Endoplasmic Reticulum Stress and Apoptosis in Rat Hippocampus

    PubMed Central

    Rodríguez-Martínez, Erika; Nava-Ruiz, Concepcion; Escamilla-Chimal, Elsa; Borgonio-Perez, Gabino; Rivas-Arancibia, Selva

    2016-01-01

    The chronic exposure to low doses of ozone, like in environmental pollution, leads to a state of oxidative stress, which has been proposed to contribute to neurodegenerative disorders, including Alzheimer’s disease (AD). It induces an increase of calcium in the endoplasmic reticulum (ER), which produces ER stress. On the other hand, different studies show that, in diseases such as Alzheimer’s, there exist disturbances in protein folding where ER plays an important role. The objective of this study was to evaluate the state of chronic oxidative stress on ER stress and its relationship with apoptotic death in the hippocampus of rats exposed to low doses of ozone. We used 108 male Wistar rats randomly divided into five groups. The groups received one of the following treatments: (1) Control (air); (2) Ozone (O3) 7 days; (3) O3 15 days; (4) O3 30 days; (5) O3 60 days; and (6) O3 90 days. Two hours after each treatment, the animals were sacrificed and the hippocampus was extracted. Afterwards, the tissue was processed for western blot and immunohistochemistry using the following antibodies: ATF6, 78 kDa glucose-regulated protein (GRP78) and caspase 12. It was also subjected to terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and electronic microscopy. Our results show an increase in ATF6, GRP78 and caspase 12 as well as ER ultrastructural alterations and an increase of TUNEL positive cells after 60 and 90 days of exposure to ozone. With the obtained results, we can conclude that oxidative stress induced by chronic exposure to low doses of ozone leads to ER stress. ER stress activates ATF6 inducing the increase of GRP78 in the cytoplasm, which leads to the increase in the nuclear translocation of ATF6. Finally, the translocation creates a vicious cycle that, together with the activation of the cascade for apoptotic cell death, contributes to the maintenance of ER stress. These events potentially contribute in the neurodegeneration processes

  1. Cellular Pathology of Pelizaeus-Merzbacher Disease Involving Chaperones Associated with Endoplasmic Reticulum Stress

    PubMed Central

    Inoue, Ken

    2017-01-01

    Disease-causing mutations in genes encoding membrane proteins may lead to the production of aberrant polypeptides that accumulate in the endoplasmic reticulum (ER). These mutant proteins have detrimental conformational changes or misfolding events, which result in the triggering of the unfolded protein response (UPR). UPR is a cellular pathway that reduces ER stress by generally inhibiting translation, increasing ER chaperones levels, or inducing cell apoptosis in severe ER stress. This process has been implicated in the cellular pathology of many neurological disorders, including Pelizaeus-Merzbacher disease (PMD). PMD is a rare pediatric disorder characterized by the failure in the myelination process of the central nervous system (CNS). PMD is caused by mutations in the PLP1 gene, which encodes a major myelin membrane protein. Severe clinical PMD phenotypes appear to be the result of cell toxicity, due to the accumulation of PLP1 mutant proteins and not due to the lack of functional PLP1. Therefore, it is important to clarify the pathological mechanisms by which the PLP1 mutants negatively impact the myelin-generating cells, called oligodendrocytes, to overcome this devastating disease. This review discusses how PLP1 mutant proteins change protein homeostasis in the ER of oligodendrocytes, especially focusing on the reaction of ER chaperones against the accumulation of PLP1 mutant proteins that cause PMD. PMID:28286750

  2. KUS121, a VCP modulator, attenuates ischemic retinal cell death via suppressing endoplasmic reticulum stress

    PubMed Central

    Hata, Masayuki; Ikeda, Hanako O.; Kikkawa, Chinami; Iwai, Sachiko; Muraoka, Yuki; Hasegawa, Tomoko; Kakizuka, Akira; Yoshimura, Nagahisa

    2017-01-01

    Ischemic neural damages cause several devastating diseases, including brain stroke and ischemic retinopathies, and endoplasmic reticulum (ER) stress has been proposed to be the underlying mechanism of the neuronal cell death of these conditions. We previously synthesized Kyoto University substances (KUSs) as modulators of valosin-containing protein (VCP); KUSs inhibit VCP ATPase activity and protect cells from different cell death-inducing insults. Here, we examined the efficacy of KUS121 in a rat model of retinal ischemic injury. Systemic administration of KUS121 to rats with ischemic retinal injury significantly suppressed inner retinal thinning and death of retinal ganglion and amacrine cells, with a significant functional maintenance of visual functions, as judged by electroretinography. Furthermore, intravitreal injection of KUS121, which is the clinically preferred route of drug administration for retinal diseases, appeared to show an equal or better neuroprotective efficacy in the ischemic retina compared with systemic administration. Indeed, induction of the ER stress marker C/EBP homologous protein (CHOP) after the ischemic insult was significantly suppressed by KUS121 administration. Our study suggests VCP modulation by KUS as a promising novel therapeutic strategy for ischemic neuronal diseases. PMID:28317920

  3. Hyperglycemia magnifies bupivacaine-induced cell apoptosis triggered by mitochondria dysfunction and endoplasmic reticulum stress.

    PubMed

    Li, Le; Ye, Xiao-ping; Lu, Ai-zhu; Zhou, Shu-qin; Liu, Hui; Liu, Zhong-jie; Jiang, Shan; Xu, Shi-yuan

    2013-06-01

    Nerve cell injury associated with apoptosis plays an important role in the development of diabetic peripheral neuropathy (DPN). However, it remains unclear whether preexisting or potential neurocyte damage induced by hyperglycemia increases sensitivity to local anesthetics. SH-SY5Y cells were pretreated with a high concentration of glucose in vitro, to imitate DPN prior to administration of bupivacaine or placebo. Cell viability and apoptosis were investigated with a CCK-8 assay and flow cytometry, respectively. In addition, mitochondrial membrane potential, reactive oxygen species (ROS), mitochondrially generated ROS, and activity of mitochondrial complexes I and III were studied to explore the molecular mechanism of bupivacaine-induced mitochondrial injury. Grp78 and caspase-12 expression were measured by qRT-PCR and Western blot, representing endoplasmic reticulum (ER) stress. Cell structure was also assessed via transmission electron microscopy. Incubation with bupivacaine decreased the activity of mitochondrial complexes I and III; increased ROS production at cell and mitochondrial levels, mitochondrial potential depolarization, and Grp78 and caspase-12 expression at both transcription and translation levels; and affected cell structure, which could be enhanced by glucose pretreatment. These findings indicate that mitochondrial dysfunction and ER stress related to ROS are involved in bupivacaine-induced apoptosis and may be enhanced by glucose administration.

  4. Endoplasmic Reticulum Stress and Autophagy in Homocystinuria Patients with Remethylation Defects

    PubMed Central

    Martínez-Pizarro, Ainhoa; Desviat, Lourdes R.; Ugarte, Magdalena; Pérez, Belén; Richard, Eva

    2016-01-01

    Proper function of endoplasmic reticulum (ER) and mitochondria is crucial for cellular homeostasis, and dysfunction at either site as well as perturbation of mitochondria-associated ER membranes (MAMs) have been linked to neurodegenerative and metabolic diseases. Previously, we have observed an increase in ROS and apoptosis levels in patient-derived fibroblasts with remethylation disorders causing homocystinuria. Here we show increased mRNA and protein levels of Herp, Grp78, IP3R1, pPERK, ATF4, CHOP, asparagine synthase and GADD45 in patient-derived fibroblasts suggesting ER stress and calcium perturbations in homocystinuria. In addition, overexpressed MAM-associated proteins (Grp75, σ-1R and Mfn2) were found in these cells that could result in mitochondrial calcium overload and oxidative stress increase. Our results also show an activation of autophagy process and a substantial degradation of altered mitochondria by mitophagy in patient-derived fibroblasts. Moreover, we have observed that autophagy was partially abolished by antioxidants suggesting that ROS participate in this process that may have a protective role. Our findings argue that alterations in Ca2+ homeostasis and autophagy may contribute to the development of this metabolic disorder and suggest a therapeutic potential in homocystinuria for agents that stabilize calcium homeostasis and/or restore the proper function of ER-mitochondria communications. PMID:26959487

  5. Arsenic trioxide induces endoplasmic reticulum stress-related events in neutrophils.

    PubMed

    Binet, François; Chiasson, Sonia; Girard, Denis

    2010-04-01

    We recently reported that the endoplasmic reticulum (ER)-induced cell pathway of apoptosis is operational in human neutrophils and that some ER stressors can accelerate this process. Recent data suggest that arsenic trioxide (As(2)O(3) or ATO), may also act as an ER stressor. The aims of the present study were to elucidate if other ER stress-related events occur in ATO-induced neutrophils, and to determine the role of caspase-4 in the proapoptotic activity of ATO. We found that ATO induced ubiquitination of proteins, and increased calcium concentration and gene expression of calcineurin in neutrophils. In addition to caspase-4, activities of caspase-3, -8 and -9 were increased by ATO. The processing of caspase-4 was reversed by a caspase-8 inhibitor, indicating that caspase-4 activation requires the action of upstream initiator components, questioning on the role of caspase-4 in ATO-induced ER stress-mediated cell apoptosis. Using caspase-4 deficient THP-1 cells, we demonstrated that the proapoptotic effect of ATO was similar to that of control caspase-4-positive cells. We conclude that ATO is an ER stressor that can induce cell apoptosis by a mechanism which does not require caspase-4. In addition, we conclude that caspase-4 activation in ATO-induced neutrophils could be involved in functions other than apoptosis.

  6. Prolonged endoplasmic reticulum stress alters placental morphology and causes low birth weight

    SciTech Connect

    Kawakami, Takashige Yoshimi, Masaki; Kadota, Yoshito; Inoue, Masahisa; Sato, Masao; Suzuki, Shinya

    2014-03-01

    The role of endoplasmic reticulum (ER) stress in pregnancy remains largely unknown. Pregnant mice were subcutaneously administered tunicamycin (Tun), an ER stressor, as a single dose [0, 50, and 100 μg Tun/kg/body weight (BW)] on gestation days (GDs) 8.5, 12.5, and 15.5. A high incidence (75%) of preterm delivery was observed only in the group treated with Tun 100 μg/kg BW at GD 15.5, indicating that pregnant mice during late gestation are more susceptible to ER stress on preterm delivery. We further examined whether prolonged in utero exposure to ER stress affects fetal development. Pregnant mice were subcutaneously administered a dose of 0, 20, 40, and 60 μg Tun/kg from GD 12.5 to 16.5. Tun treatment decreased the placental and fetal weights in a dose-dependent manner. Histological evaluation showed the formation of a cluster of spongiotrophoblast cells in the labyrinth zone of the placenta of Tun-treated mice. The glycogen content of the fetal liver and placenta from Tun-treated mice was lower than that from control mice. Tun treatment decreased mRNA expression of Slc2a1/glucose transporter 1 (GLUT1), which is a major transporter for glucose, but increased placental mRNA levels of Slc2a3/GLUT3. Moreover, maternal exposure to Tun resulted in a decrease in vascular endothelial growth factor receptor-1 (VEGFR-1), VEGFR-2, and placental growth factor. These results suggest that excessive and exogenous ER stress may induce functional abnormalities in the placenta, at least in part, with altered GLUT and vascular-related gene expression, resulting in low infant birth weight. - Highlights: • Maternal exposure to excessive ER stress induced preterm birth and IUGR. • Prolonged excessive ER stress altered the formation of the placental labyrinth. • ER stress decreased GLUT1 mRNA expression in the placenta, but increased GLUT3. • ER stress-induced IUGR causes decreased glycogen and altered glucose transport.

  7. Aberrant Mucin Assembly in Mice Causes Endoplasmic Reticulum Stress and Spontaneous Inflammation Resembling Ulcerative Colitis

    PubMed Central

    Price, Gareth R; Tauro, Sharyn B; Taupin, Douglas; Thornton, David J; Png, Chin Wen; Crockford, Tanya L; Cornall, Richard J; Adams, Rachel; Kato, Masato; Nelms, Keats A; Hong, Nancy A; Florin, Timothy H. J; Goodnow, Christopher C; McGuckin, Michael A

    2008-01-01

    Background MUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. The inflammatory bowel disease ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, but the aetiology remains obscure. In this study we used random mutagenesis to produce two murine models of inflammatory bowel disease, characterised the basis and nature of the inflammation in these mice, and compared the pathology with human ulcerative colitis. Methods and Findings By murine N-ethyl-N-nitrosourea mutagenesis we identified two distinct noncomplementing missense mutations in Muc2 causing an ulcerative colitis-like phenotype. 100% of mice of both strains developed mild spontaneous distal intestinal inflammation by 6 wk (histological colitis scores versus wild-type mice, p < 0.01) and chronic diarrhoea. Monitoring over 300 mice of each strain demonstrated that 25% and 40% of each strain, respectively, developed severe clinical signs of colitis by age 1 y. Mutant mice showed aberrant Muc2 biosynthesis, less stored mucin in goblet cells, a diminished mucus barrier, and increased susceptibility to colitis induced by a luminal toxin. Enhanced local production of IL-1β, TNF-α, and IFN-γ was seen in the distal colon, and intestinal permeability increased 2-fold. The number of leukocytes within mesenteric lymph nodes increased 5-fold and leukocytes cultured in vitro produced more Th1 and Th2 cytokines (IFN-γ, TNF-α, and IL-13). This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis, and wound repair. Expression of mutated Muc2 oligomerisation domains in vitro demonstrated that aberrant Muc2 oligomerisation underlies the ER stress. In human ulcerative colitis we demonstrate similar

  8. Androgen Mediated Regulation of Endoplasmic Reticulum-Associated Degradation and its Effects on Prostate Cancer

    PubMed Central

    Erzurumlu, Yalcin; Ballar, Petek

    2017-01-01

    The endoplasmic reticulum (ER) comprises thirty percent of the newly translated proteins in eukaryotic cells. The quality control mechanism within the ER distinguishes between properly and improperly folded proteins and ensures that unwanted proteins are retained in the ER and subsequently degraded through ER-associated degradation (ERAD). Besides cleaning of misfolded proteins ERAD is also important for physiological processes by regulating the abundance of normal proteins of the ER. Thus it is important to unreveal the regulation patterns of ERAD. Here, we describe that ERAD pathway is regulated by androgen, where its inhibitor SVIP was downregulated, all other ERAD genes were upregulated. Consistently, androgen treatment increased the degradation rate of ERAD substrates. Using several independent techniques, we showed that this regulation is through androgen receptor transactivation. ERAD genes found to be upregulated in prostate cancer tissues and silencing expression of Hrd1, SVIP, and gp78 reduced the in vitro migration and malignant transformation of LNCaP cells. Our data suggests that expression levels of ERAD components are regulated by androgens, that promotes ERAD proteolytic activity, which is positively related with prostate tumorigenesis. PMID:28091582

  9. The plant-unique cis-element that mediates signaling from multiple endoplasmic reticulum stress sensors.

    PubMed

    Hayashi, Shimpei; Takaiwa, Fumio

    2013-06-01

    The accumulation of unfolded proteins in the ER lumen induces intracellular signaling mediated by the ER stress sensor protein IRE1. Our recent study identified a new common cis-element of ER stress-responsive genes (such as rice BiP paralogs and WRKY45) that were regulated via an IRE1-dependent pathway. ER stress-responsive cis-elements had been expected to be conserved between plants and mammals. However, contrary to expectations, sequences of the plant cis-element, pUPRE-II, were not identical to those of its mammalian counterpart. Additionally, pUPRE-II also interacted with another ER stress sensor protein and mediated multiple signaling pathways. Here, we provide a summary of the results that suggest the complicated mechanism underlying the regulation of ER stress-responsive gene expression in plants.

  10. Polyurethane conjugating TGF-β on surface impacts local inflammation and endoplasmic reticulum stress in skeletal muscle.

    PubMed

    Shi, Dandan; Xiao, Jiangwei; Gu, Ruicai; Wu, Gang; Liao, Hua

    2017-04-01

    The synthesized short peptide-polymers would provide key functions for tissue regeneration and repair, through enriching bioactive molecules on polymers or releasing these molecules pre-conjugated on the materials. We have developed a degradable polyurethane (PU) bearing HSNGLPL peptide, which has affinity binding ability to transforming growth factor-betas (TGF-β). For deeply understanding spatial release of TGF-β from the PU polymers and its localized bioactivity, quartz crystal microbalance (QCM) and Elisa test were used to verify TGF-β binding capacities in vitro and in vivo. The PU polymers, with or without pre-conjugating of TGF-β, were implanted into gastronomies muscle (GN) of C57BL/6 mice, for addressing TGF-β release from the polymers and its bio-regulating function in vivo. QCM result shows that PU bearing HSNGLPL peptide has affinity binding ability to TGF-β in vitro. Intramuscular implanting experiment further supports the enrichment efficiency of TGF-β on PU polymers in vivo. The detecting data involving intramuscular inflammatory infiltration triggered by the implants, myofiber regeneration, muscular fibrosis degree, and activation of endoplasmic reticulum stress (ER stress), evidence TGF-β can be released from PU polymers, and exerts regulating effects on the material-induced inflammation. Thus, our present results suggest it is feasible to improve biocompatibility of PU polymers in vivo, by pre-bearing bioactive molecules on materials before the implanting. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1156-1165, 2017.

  11. Kaempferol induces apoptosis in HepG2 cells via activation of the endoplasmic reticulum stress pathway.

    PubMed

    Guo, Haiqing; Ren, Feng; Zhang, Li; Zhang, Xiangying; Yang, Rongrong; Xie, Bangxiang; Li, Zhuo; Hu, Zhongjie; Duan, Zhongping; Zhang, Jing

    2016-03-01

    Kaempferol is a flavonoid compound that has gained importance due to its antitumor properties; however, the underlying mechanisms remain to be fully understood. The present study aimed to investigate the molecular mechanisms of the antitumor function of kaempferol in HepG2 hepatocellular carcinoma cells. Kaempferol was determined to reduce cell viability, increase lactate dehydrogenase activity and induce apoptosis in a concentration‑ and time‑dependent manner in HepG2 cells. Additionally, kaempferol‑induced apoptosis possibly acts via the endoplasmic reticulum (ER) stress pathway, due to the significant increase in the protein expression levels of glucose‑regulated protein 78, glucose‑regulated protein 94, protein kinase R‑like ER kinase, inositol‑requiring enzyme 1α, partial activating transcription factor 6 cleavage, caspase‑4, C/EBP homologous protein (CHOP) and cleaved caspase‑3. The pro‑apoptotic activity of kaempferol was determined to be due to induction of the ER stress‑CHOP pathway, as: i) ER stress was blocked by 4‑phenyl butyric acid (4‑PBA) pretreatment and knockdown of CHOP with small interfering RNA, which resulted in alleviation of kaempferol‑induced HepG2 cell apoptosis; and ii) transfection with plasmid overexpressing CHOP reversed the protective effect of 4‑PBA in kaempferol‑induced HepG2 cells and increased the apoptotic rate. Thus, kaempferol promoted HepG2 cell apoptosis via induction of the ER stress‑CHOP signaling pathway. These observations indicate that kaempferol may be used as a potential chemopreventive treatment strategy for patients with hepatocellular carcinoma.

  12. Cytokines downregulate the sarcoendoplasmic reticulum pump Ca2+ ATPase 2b and deplete endoplasmic reticulum Ca2+, leading to induction of endoplasmic reticulum stress in pancreatic beta-cells.

    PubMed

    Cardozo, Alessandra K; Ortis, Fernanda; Storling, Joachim; Feng, Ying-Mei; Rasschaert, Joanne; Tonnesen, Morten; Van Eylen, Françoise; Mandrup-Poulsen, Thomas; Herchuelz, André; Eizirik, Décio L

    2005-02-01

    Cytokines and free radicals are mediators of beta-cell death in type 1 diabetes. Under in vitro conditions, interleukin-1beta (IL-1beta) + gamma-interferon (IFN-gamma) induce nitric oxide (NO) production and apoptosis in rodent and human pancreatic beta-cells. We have previously shown, by microarray analysis of primary beta-cells, that IL-1beta + IFN-gamma decrease expression of the mRNA encoding for the sarcoendoplasmic reticulum pump Ca(2+) ATPase 2b (SERCA2b) while inducing expression of the endoplasmic reticulum stress-related and proapoptotic gene CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein). In the present study we show that cytokine-induced apoptosis and necrosis in primary rat beta-cells and INS-1E cells largely depends on NO production. IL-1beta + IFN-gamma, via NO synthesis, markedly decreased SERCA2b protein expression and depleted ER Ca(2+) stores. Of note, beta-cells showed marked sensitivity to apoptosis induced by SERCA blockers, as compared with fibroblasts. Cytokine-induced ER Ca(2+) depletion was paralleled by an NO-dependent induction of CHOP protein and activation of diverse components of the ER stress response, including activation of inositol-requiring ER-to-nucleus signal kinase 1alpha (IRE1alpha) and PRK (RNA-dependent protein kinase)-like ER kinase (PERK)/activating transcription factor 4 (ATF4), but not ATF6. In contrast, the ER stress-inducing agent thapsigargin triggered these four pathways in parallel. In conclusion, our results suggest that the IL-1beta + IFN-gamma-induced decrease in SERCA2b expression, with subsequent depletion of ER Ca(2+) and activation of the ER stress pathway, is a potential contributory mechanism to beta-cell death.

  13. Cadmium-induced teratogenicity: Association with ROS-mediated endoplasmic reticulum stress in placenta

    SciTech Connect

    Wang, Zhen; Wang, Hua; Xu, Zhong Mei; Ji, Yan-Li; Chen, Yuan-Hua; Zhang, Zhi-Hui; Zhang, Cheng; Meng, Xiu-Hong; Zhao, Mei; Xu, De-Xiang

    2012-03-01

    The placenta is essential for sustaining the growth of the fetus. An increased endoplasmic reticulum (ER) stress has been associated with the impaired placental and fetal development. Cadmium (Cd) is a potent teratogen that caused fetal malformation and growth restriction. The present study investigated the effects of maternal Cd exposure on placental and fetal development. The pregnant mice were intraperitoneally injected with CdCl{sub 2} (4.5 mg/kg) on gestational day 9. As expected, maternal Cd exposure during early limb development significantly increased the incidences of forelimb ectrodactyly in fetuses. An obvious impairment in the labyrinth, a highly developed tissue of blood vessels, was observed in placenta of mice treated with CdCl{sub 2}. In addition, maternal Cd exposure markedly repressed cell proliferation and increased apoptosis in placenta. An additional experiment showed that maternal Cd exposure significantly upregulated the expression of GRP78, an ER chaperone. Moreover, maternal Cd exposure induced the phosphorylation of placental eIF2α, a downstream molecule of PERK signaling. In addition, maternal Cd exposure significantly increased the level of placental CHOP, another target of PERK signaling, indicating that the unfolded protein response (UPR) signaling was activated in placenta of mice treated with CdCl{sub 2}. Interestingly, alpha-phenyl-N-t-butylnitrone, a free radical spin-trapping agent, significantly alleviated Cd-induced placental ER stress and UPR. Taken together, these results suggest that reactive oxygen species (ROS)-mediated ER stress might be involved in Cd-induced impairment on placental and fetal development. Antioxidants may be used as pharmacological agents to protect against Cd-induced fetal malformation and growth restriction. -- Highlights: ► Cd induces fetal malformation and growth restriction. ► Cd induced placental ER stress and UPR. ► PBN alleviates Cd-induced ER stress and UPR in placenta. ► ROS-mediated ER

  14. Glutamine treatment attenuates endoplasmic reticulum stress and apoptosis in TNBS-induced colitis.

    PubMed

    Crespo, Irene; San-Miguel, Beatriz; Prause, Carolina; Marroni, Norma; Cuevas, María J; González-Gallego, Javier; Tuñón, María J

    2012-01-01

    Endoplasmic reticulum (ER) stress and apoptotic cell death play an important role in the pathogenesis and perpetuation of inflammatory bowel disease (IBD). We aimed to explore the potential of glutamine to reduce ER stress and apoptosis in a rat model of experimental IBD. Colitis was induced in male Wistar rats by intracolonic administration of 30 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Glutamine (25 mg/dL) was given by rectal route daily for 2 d or 7 d. Both oxidative stress (TBARS concentration and oxidised/reduced glutathione ratio) and ER stress markers (CHOP, BiP, calpain-1 and caspase-12 expression) increased significantly within 48 h of TNBS instillation, and glutamine attenuated the extent of the changes. Glutamine also inhibited the significant increases of ATF6, ATF4 and spliced XBP-1 mRNA levels induced by TNBS instillation. TNBS-colitis resulted in a significant increase in p53 and cytochrome c expression, and a reduced Bcl-xL expression and Bax/Bcl-2 ratio. These effects were significantly inhibited by glutamine. Treatment with the amino acid also resulted in significant decreases of caspase-9, caspase-8 and caspase-3 activities. Double immunofluorescence staining showed co-localization of CHOP and cleaved caspase-3 in colon sections. Phospho-JNK and PARP-1 expression was also significantly higher in TNBS-treated rats, and treatment with glutamine significantly decreased JNK phosphorylation and PARP-1 proteolysis. To directly address the effect of glutamine on ER stress and apoptosis in epithelial cells, the ER stress inducers brefeldin A and tunicamycin were added to Caco-2 cells that were treated with glutamine (5 mM and 10 mM). The significant enhancement in PERK, ATF6 phosphorylated IRE1, BiP and cleaved caspase-3 expression induced by brefeldin A and tunicamycin was partly prevented by glutamine. Data obtained indicated that modulation of ER stress signalling and anti-apoptotic effects contribute to protection by glutamine against damage

  15. Cigarette smoke induces endoplasmic reticulum stress and the unfolded protein response in normal and malignant human lung cells

    PubMed Central

    Jorgensen, Ellen; Stinson, Andy; Shan, Lin; Yang, Jin; Gietl, Diana; Albino, Anthony P

    2008-01-01

    Background Although lung cancer is among the few malignancies for which we know the primary etiological agent (i.e., cigarette smoke), a precise understanding of the temporal sequence of events that drive tumor progression remains elusive. In addition to finding that cigarette smoke (CS) impacts the functioning of key pathways with significant roles in redox homeostasis, xenobiotic detoxification, cell cycle control, and endoplasmic reticulum (ER) functioning, our data highlighted a defensive role for the unfolded protein response (UPR) program. The UPR promotes cell survival by reducing the accumulation of aberrantly folded proteins through translation arrest, production of chaperone proteins, and increased degradation. Importance of the UPR in maintaining tissue health is evidenced by the fact that a chronic increase in defective protein structures plays a pathogenic role in diabetes, cardiovascular disease, Alzheimer's and Parkinson's syndromes, and cancer. Methods Gene and protein expression changes in CS exposed human cell cultures were monitored by high-density microarrays and Western blot analysis. Tissue arrays containing samples from 110 lung cancers were probed with antibodies to proteins of interest using immunohistochemistry. Results We show that: 1) CS induces ER stress and activates components of the UPR; 2) reactive species in CS that promote oxidative stress are primarily responsible for UPR activation; 3) CS exposure results in increased expression of several genes with significant roles in attenuating oxidative stress; and 4) several major UPR regulators are increased either in expression (i.e., BiP and eIF2α) or phosphorylation (i.e., phospho-eIF2α) in a majority of human lung cancers. Conclusion These data indicate that chronic ER stress and recruitment of one or more UPR effector arms upon exposure to CS may play a pivotal role in the etiology or progression of lung cancers, and that phospho-eIF2α and BiP may have diagnostic and

  16. Activating transcription factor 4 is involved in endoplasmic reticulum stress-mediated apoptosis contributing to vascular calcification.

    PubMed

    Duan, Xiao-Hui; Chang, Jin-Rui; Zhang, Jing; Zhang, Bao-Hong; Li, Yu-Lin; Teng, Xu; Zhu, Yi; Du, Jie; Tang, Chao-Shu; Qi, Yong-Fen

    2013-09-01

    Our previous work reported that endoplasmic reticulum stress (ERS)-mediated apoptosis was activated during vascular calcification (VC). Activating transcription factor 4 (ATF4) is a critical transcription factor in osteoblastogenesis and ERS-induced apoptosis. However, whether ATF4 is involved in ERS-mediated apoptosis contributing to VC remains unclear. In the present study, in vivo VC was induced in rats by administering vitamin D3 plus nicotine. Vascular smooth muscle cell (VSMC) calcification in vitro was induced by incubation in calcifying media containing β-glycerophosphate and CaCl2. ERS inhibitors taurine or 4-phenylbutyric acid attenuated ERS and VSMC apoptosis in calcified rat arteries, reduced calcification and retarded the VSMC contractile phenotype transforming into an osteoblast-like phenotype in vivo. Inhibition of ERS retarded the VSMC phenotypic transition into an osteoblast-like cell phenotype and reduced VSMC calcification and apoptosis in vitro. Interestingly, ATF4 was activated in calcified aortas and calcified VSMCs in vitro. ATF4 knockdown attenuated ERS-induced apoptosis in calcified VSMCs. ATF4 deficiency blocked VSMC calcification and negatively regulated the osteoblast phenotypic transition of VSMCs in vitro. Our results demonstrate that ATF4 was involved at least in part in the process of ERS-mediated apoptosis contributing to VC.

  17. Vertical sleeve gastrectomy reduces blood pressure and hypothalamic endoplasmic reticulum stress in mice.

    PubMed

    McGavigan, Anne K; Henseler, Zachariah M; Garibay, Darline; Butler, Scott D; Jayasinghe, Sisitha; Ley, Ruth E; Davisson, Robin L; Cummings, Bethany P

    2017-03-01

    Bariatric surgery, such as vertical sleeve gastrectomy (VSG), causes remarkable improvements in cardiometabolic health, including hypertension remission. However, the mechanisms responsible remain undefined and poorly studied. Therefore, we developed and validated the first murine model of VSG that recapitulates the blood pressure-lowering effect of VSG using gold-standard radiotelemetry technology. We used this model to investigate several potential mechanisms, including body mass, brain endoplasmic reticulum (ER) stress signaling and brain inflammatory signaling, which are all critical contributors to the pathogenesis of obesity-associated hypertension. Mice fed on a high-fat diet underwent sham or VSG surgery and radiotelemeter implantation. Sham mice were fed ad libitum or were food restricted to match their body mass to VSG-operated mice to determine the role of body mass in the ability of VSG to lower blood pressure. Blood pressure was then measured in freely moving unstressed mice by radiotelemetry. VSG decreased energy intake, body mass and fat mass. Mean arterial blood pressure (MAP) was reduced in VSG-operated mice compared with both sham-operated groups. VSG-induced reductions in MAP were accompanied by a body mass-independent decrease in hypothalamic ER stress, hypothalamic inflammation and sympathetic nervous system tone. Assessment of gut microbial populations revealed VSG-induced increases in the relative abundance of Gammaproteobacteria and Enterococcus, and decreases in Adlercreutzia These results suggest that VSG reduces blood pressure, but this is only partly due to the reduction in body weight. VSG-induced reductions in blood pressure may be driven by a decrease in hypothalamic ER stress and inflammatory signaling, and shifts in gut microbial populations.

  18. Tauroursodeoxycholic acid reduces endoplasmic reticulum stress, acinar cell damage, and systemic inflammation in acute pancreatitis.

    PubMed

    Seyhun, Ersin; Malo, Antje; Schäfer, Claus; Moskaluk, Christopher A; Hoffmann, Ralf-Thorsten; Göke, Burkhard; Kubisch, Constanze H

    2011-11-01

    In acute pancreatitis, endoplasmic reticulum (ER) stress prompts an accumulation of malfolded proteins inside the ER, initiating the unfolded protein response (UPR). Because the ER chaperone tauroursodeoxycholic acid (TUDCA) is known to inhibit the UPR in vitro, this study examined the in vivo effects of TUDCA in an acute experimental pancreatitis model. Acute pancreatitis was induced in Wistar rats using caerulein, with or without prior TUDCA treatment. UPR components were analyzed, including chaperone binding protein (BiP), phosphorylated protein kinase-like ER kinase (pPERK), X-box binding protein (XBP)-1, phosphorylated c-Jun NH(2)-terminal kinase (pJNK), CCAAT/enhancer binding protein homologues protein, and caspase 12 and 3 activation. In addition, pancreatitis biomarkers were measured, such as serum amylase, trypsin activation, edema formation, histology, and the inflammatory reaction in pancreatic and lung tissue. TUDCA treatment reduced intracellular trypsin activation, edema formation, and cell damage, while leaving amylase levels unaltered. The activation of myeloperoxidase was clearly reduced in pancreas and lung. Furthermore, TUDCA prevented caerulein-induced BiP upregulation, reduced XBP-1 splicing, and caspase 12 and 3 activation. It accelerated the downregulation of pJNK. In controls without pancreatitis, TUDCA showed cytoprotective effects including pPERK signaling and activation of downstream targets. We concluded that ER stress responses activated in acute pancreatitis are grossly attenuated by TUDCA. The chaperone reduced the UPR and inhibited ER stress-associated proapoptotic pathways. TUDCA has a cytoprotective potential in the exocrine pancreas. These data hint at new perspectives for an employment of chemical chaperones, such as TUDCA, in prevention of acute pancreatitis.

  19. Vertical sleeve gastrectomy reduces blood pressure and hypothalamic endoplasmic reticulum stress in mice

    PubMed Central

    McGavigan, Anne K.; Henseler, Zachariah M.; Garibay, Darline; Butler, Scott D.; Jayasinghe, Sisitha; Ley, Ruth E.; Davisson, Robin L.

    2017-01-01

    ABSTRACT Bariatric surgery, such as vertical sleeve gastrectomy (VSG), causes remarkable improvements in cardiometabolic health, including hypertension remission. However, the mechanisms responsible remain undefined and poorly studied. Therefore, we developed and validated the first murine model of VSG that recapitulates the blood pressure-lowering effect of VSG using gold-standard radiotelemetry technology. We used this model to investigate several potential mechanisms, including body mass, brain endoplasmic reticulum (ER) stress signaling and brain inflammatory signaling, which are all critical contributors to the pathogenesis of obesity-associated hypertension. Mice fed on a high-fat diet underwent sham or VSG surgery and radiotelemeter implantation. Sham mice were fed ad libitum or were food restricted to match their body mass to VSG-operated mice to determine the role of body mass in the ability of VSG to lower blood pressure. Blood pressure was then measured in freely moving unstressed mice by radiotelemetry. VSG decreased energy intake, body mass and fat mass. Mean arterial blood pressure (MAP) was reduced in VSG-operated mice compared with both sham-operated groups. VSG-induced reductions in MAP were accompanied by a body mass-independent decrease in hypothalamic ER stress, hypothalamic inflammation and sympathetic nervous system tone. Assessment of gut microbial populations revealed VSG-induced increases in the relative abundance of Gammaproteobacteria and Enterococcus, and decreases in Adlercreutzia. These results suggest that VSG reduces blood pressure, but this is only partly due to the reduction in body weight. VSG-induced reductions in blood pressure may be driven by a decrease in hypothalamic ER stress and inflammatory signaling, and shifts in gut microbial populations. PMID:28093508

  20. Sulforaphane Improves Ischemia-Induced Detrusor Overactivity by Downregulating the Enhancement of Associated Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Rat Bladder

    PubMed Central

    Tai, Huai-Ching; Chung, Shiu-Dong; Chien, Chiang-Ting; Yu, Hong-Jeng

    2016-01-01

    Atherosclerosis-associated pelvic ischemia has been reported to be a risk factor for bladder dysfunction and subsequent lower urinary tract symptoms (LUTS) in the elderly population. However, the molecular mechanisms of this association remain unclear. We hypothesized that stress-induced cellular responses might play a role in the pathogenesis of ischemia-induced bladder dysfunction. In the present study, the animal model of bladder ischemia was induced by bilateral partial arterial occlusion (BPAO) in rats. We found that BPAO significantly induced the presence of detrusor overactivity (DO) and upregulated the expression of several molecular reactions, including biomarkers in endoplasmic reticulum stress (78 kDa glucose-regulated protein, GRP78 and C/EBP-homologous protein, CHOP), autophagy (Beclin-1, p62 and LC3 II) and apoptosis (caspase 3). BPAO also disturbed the Kelch-like ECH-associated protein 1–nuclear factor erythroid-2-related factor 2 (Keap1–Nrf2) pathways. These responses might collectively alter muscarinic and purinergic signaling and contribute to the presence of DO in the ischemic bladder. Therapeutically, treatment with neither a muscarinic nor purinergic receptor antagonist restored bladder function. Interestingly, sulforaphane effectively attenuated ischemia-enhanced endoplasmic reticulum stress, autophagy and apoptosis in the bladder, subsequently ameliorated ischemia-induced bladder dysfunction and might emerge as a novel strategy to protect the bladder against ischemia-induced oxidative damage. PMID:27824068

  1. Astragaloside IV Attenuates Podocyte Apoptosis Mediated by Endoplasmic Reticulum Stress through Upregulating Sarco/Endoplasmic Reticulum Ca2+-ATPase 2 Expression in Diabetic Nephropathy

    PubMed Central

    Guo, Hengjiang; Cao, Aili; Chu, Shuang; Wang, Yi; Zang, Yingjun; Mao, Xiaodong; Wang, Hao; Wang, Yunman; Liu, Cheng; Zhang, Xuemei; Peng, Wen

    2016-01-01

    Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) plays a central role in the pathogenesis of diabetes. This protein has been recognized as a potential target for diabetic therapy. In this study, we identified astragaloside IV (AS-IV) as a potent modulator of SERCA inhibiting renal injury in diabetic status. Increasing doses of AS-IV (2, 6, and 18 mg kg-1 day-1) were administered intragastrically to db/db mice for 8 weeks. Biochemical and histopathological approaches were conducted to evaluate the therapeutic effects of AS-IV. Cultured mouse podocytes were used to further explore the underlying mechanism in vitro. AS-IV dose-dependently increased SERCA activity and SERCA2 expression, and suppressed ER stress-mediated and mitochondria-mediated apoptosis in db/db mouse kidney. AS-IV also normalized glucose tolerance and insulin sensitivity, improved renal function, and ameliorated glomerulosclerosis and renal inflammation in db/db mice. In palmitate stimulated podocytes, AS-IV markedly improved inhibitions of SERCA activity and SERCA2 expression, restored intracellular Ca2+ homeostasis, and attenuated podocyte apoptosis in a dose-dependent manner with a concomitant abrogation of ER stress as evidenced by the downregulation of GRP78, cleaved ATF6, phospho-IRE1α and phospho-PERK, and the inactivation of both ER stress-mediated and mitochondria-mediated apoptotic pathways. Furthermore, SERCA2b knockdown eliminated the effect of AS-IV on ER stress and ER stress-mediated apoptotic pathway, whereas its overexpression exhibited an anti-apoptotic effect. Our data obtained from in vivo and in vitro studies demonstrate that AS-IV attenuates renal injury in diabetes subsequent to inhibiting ER stress-induced podocyte apoptosis through restoring SERCA activity and SERCA2 expression. PMID:28066247

  2. Protein kinase R-like ER kinase and its role in endoplasmic reticulum stress-decided cell fate.

    PubMed

    Liu, Z; Lv, Y; Zhao, N; Guan, G; Wang, J

    2015-07-30

    Over the past few decades, understandings and evidences concerning the role of endoplasmic reticulum (ER) stress in deciding the cell fate have been constantly growing. Generally, during ER stress, the signal transductions are mainly conducted by three ER stress transducers: protein kinase R-like endoplasmic reticulum kinase (PERK), inositol-requiring kinase 1 (IRE1) and activating transcription factor 6 (ATF6). Consequently, the harmful stimuli from the ER stress transducers induce apoptosis and autophagy, which share several crosstalks and eventually decide the cell fate. The dominance of apoptosis or autophagy induced by ER stress depends on the type and degree of the stimuli. When ER stress is too severe and prolonged, apoptosis is induced to eliminate the damaged cells; however, when stimuli are mild, cell survival is promoted to maintain normal physiological functions by inducing autophagy. Although all the three pathways participate in ER stress-induced apoptosis and autophagy, PERK shows several unique characteristics by interacting with some specific downstream effectors. Notably, there are some preliminary findings on PERK-dependent mechanisms switching autophagy and apoptosis. In this review, we particularly focused on the novel, intriguing and complicated role of PERK in ER stress-decided cell fate, and also discussed more roles of PERK in restoring cellular homeostasis. However, more in-depth knowledge of PERK in the future would facilitate our understanding about many human diseases and benefit in searching for new molecular therapeutic targets.

  3. Microgravity induces proteomics changes involved in endoplasmic reticulum stress and mitochondrial protection

    PubMed Central

    Feger, Bryan J.; Thompson, J. Will; Dubois, Laura G.; Kommaddi, Reddy P.; Foster, Matthew W.; Mishra, Rajashree; Shenoy, Sudha K.; Shibata, Yoichiro; Kidane, Yared H.; Moseley, M. Arthur; Carnell, Lisa S.; Bowles, Dawn E.

    2016-01-01

    On Earth, biological systems have evolved in response to environmental stressors, interactions dictated by physical forces that include gravity. The absence of gravity is an extreme stressor and the impact of its absence on biological systems is ill-defined. Astronauts who have spent extended time under conditions of minimal gravity (microgravity) experience an array of biological alterations, including perturbations in cardiovascular function. We hypothesized that physiological perturbations in cardiac function in microgravity may be a consequence of alterations in molecular and organellar dynamics within the cellular milieu of cardiomyocytes. We used a combination of mass spectrometry-based approaches to compare the relative abundance and turnover rates of 848 and 196 proteins, respectively, in rat neonatal cardiomyocytes exposed to simulated microgravity or normal gravity. Gene functional enrichment analysis of these data suggested that the protein content and function of the mitochondria, ribosomes, and endoplasmic reticulum were differentially modulated in microgravity. We confirmed experimentally that in microgravity protein synthesis was decreased while apoptosis, cell viability, and protein degradation were largely unaffected. These data support our conclusion that in microgravity cardiomyocytes attempt to maintain mitochondrial homeostasis at the expense of protein synthesis. The overall response to this stress may culminate in cardiac muscle atrophy. PMID:27670941

  4. Ethanol promotes saturated fatty acid-induced hepatoxicity through endoplasmic reticulum (ER) stress response.

    PubMed

    Yi, Hong-Wei; Ma, Yu-Xiang; Wang, Xiao-Ning; Wang, Cui-Fen; Lu, Jian; Cao, Wei; Wu, Xu-Dong

    2015-04-01

    Serum palmitic acid (PA), a type of saturated fatty acid, causes lipid accumulation and induces toxicity in hepatocytes. Ethanol (EtOH) is metabolized by the liver and induces hepatic injury and inflammation. Herein, we analyzed the effects of EtOH on PA-induced lipotoxicity in the liver. Our results indicated that EtOH aggravated PA-induced apoptosis and lipid accumulation in primary rat hepatocytes in dose-dependent manner. EtOH intensified PA-caused endoplasmic reticulum (ER) stress response in vitro and in vivo, and the expressions of CHOP, ATF4, and XBP-1 in nucleus were significantly increased. EtOH also increased PA-caused cleaved caspase-3 in cytoplasm. In wild type and CHOP(-/-) mice treated with EtOH and high fat diet (HFD), EtOH worsened the HFD-induced liver injury and dyslipidemia, while CHOP knockout blocked toxic effects of EtOH and PA. Our study suggested that targeting UPR-signaling pathways is a promising, novel approach to reducing EtOH and saturated fatty acid-induced metabolic complications.

  5. Endoplasmic reticulum stress as a novel cellular response to di (2-ethylhexyl) phthalate exposure.

    PubMed

    Peropadre, Ana; Fernández Freire, Paloma; Pérez Martín, José Manuel; Herrero, Óscar; Hazen, María José

    2015-12-25

    Di (2-ethylhexyl) phthalate is a high-production chemical widely used as a plasticizer for polyvinyl chloride products. Due to its ubiquitous presence in environmental compartments and the constant exposure of the general population through ingestion, inhalation, and dermal absorption, this compound has been subjected to extensive in vivo and in vitro toxicological studies. Despite the available information, research on the cytotoxicity of di (2-ethylhexyl) phthalate in mammalian cells is relatively limited.In this paper, an in vitro multi-parametric approach was used to provide further mechanistic data on the toxic activity of this chemical in Vero and HaCaT cells. Our results reveal that a 24 h exposure to di (2-ethylhexyl) phthalate causes, in both cell lines, an inhibition of cell proliferation that was linked to cell cycle delay at the G1 phase. Concomitantly, the tested compound induces mild endoplasmic reticulum stress which leads to an adaptive rather than a pro-apoptotic response in mammalian cells. These findings demonstrate that there are multiple potential cellular targets of di (2-ethylhexyl) phthalate-induced toxicity and the need to develop further experimental studies for the risk assessment of this ubiquitous plasticizer.

  6. The role of endoplasmic reticulum stress and insulin resistance in the occurrence of goose fatty liver.

    PubMed

    Geng, Tuoyu; Xia, Lili; Li, Fuyuan; Xia, Jing; Zhang, Yihui; Wang, Qianqian; Yang, Biao; Montgomery, Sean; Cui, Hengmi; Gong, Daoqing

    2015-09-11

    In mammals, insulin resistance (IR) is required for the occurrence of non-alcoholic fatty liver disease, and endoplasmic reticulum stress (ERS) contributes to IR. As geese have physiological and metabolic characteristics different from mammals, it is unclear whether these mechanisms also underlie the occurrence of goose fatty liver. To address this, 70-day-old geese were treated with an ERS inducer or overfed, and variables associated with ERS or IR were subsequently determined. The data indicated that the group of geese treated with the ERS inducer for 20d appeared to be more intolerant to blood glucose than the control group, and their livers showed features of hepatic steatosis, suggesting ERS can induce IR and hepatic steatosis in geese. In contrast, overfeeding did not induce ERS, probably due to the upregulated expression of fatty acid desaturases, but induced higher fasting/postprandial blood glucose as well as glucose intolerance in geese, which was accompanied by a dramatic increase of liver weight. Taken together, these findings delineated the role of ERS and IR in the occurrence of goose fatty liver.

  7. Effects of endoplasmic reticulum stress on the expression of inflammatory cytokines in patients with ulcerative colitis

    PubMed Central

    Li, Nan; Wang, Xue-Ming; Jiang, Li-Jun; Zhang, Meng; Li, Na; Wei, Zhen-Zhen; Zheng, Nan; Zhao, Ya-Jiao

    2016-01-01

    AIM: To explore the changes of X-box binding protein 1 splicing (XBP1s) and inflammatory cytokine expression in patients with ulcerative colitis (UC) in response to endoplasmic reticulum stress (ERS). METHODS: Reverse transcription polymerase chain reaction and quantitative polymerase chain reaction were performed to detect the forms of XBP1s and the expression of interleukin (IL)-2, interferon (IFN)-γ, and IL-17α. Differences between patients with UC and normal subjects were then determined. RESULTS: Mononuclear cells of the peripheral blood of normal subjects and UC patients with were stimulated with no drugs (control), phytohemagglutinin (PHA), thapsigargin (TG), or both PHA and TG. XBP1s in patients with UC exhibited splicing, which was greater with co-stimulation than single stimulation. Co-stimulation increased the expression level of IL-2, IFN-γ, and IL-17α. CONCLUSION: The T lymphocytes of both normal subjects and patients with UC responded to ERS by activating the XBP1s-mediated signalling pathway, upregulating the expression of inflammatory cytokines, and increasing the occurrence of inflammation. The mononuclear cells in the peripheral blood of patients with UC were more sensitive to ERS than those in the peripheral blood of normal subjects. PMID:26900298

  8. Ursolic acid inhibits the development of nonalcoholic fatty liver disease by attenuating endoplasmic reticulum stress.

    PubMed

    Li, Jian-Shuang; Wang, Wen-Jun; Sun, Yu; Zhang, Yu-Hao; Zheng, Ling

    2015-05-01

    Ursolic acid (UA) is a natural pentacyclic triterpenoid compound, which is enriched with many herbs and plants, such as apple, cranberry and olive. UA performs multiple biological activities including anti-oxidation, anti-inflammation, anti-cancer and hepatoprotection. However, the exact mechanism underlying the hepatoprotective activity of UA remains unclear. In this study, the effects of UA on the development of nonalcoholic fatty liver disease (NAFLD) were investigated. In vivo, UA treatment (0.14%, w/w) significantly decreased the liver weight, serum levels of ALT/AST and hepatic steatosis in db/db mice (a type 2 diabetic mouse model). In vitro, UA treatment (10-30 μg ml(-1)) significantly decreased palmitic acid induced intracellular lipid accumulation in L02 cells. Our results suggested that the beneficial effects of UA on NAFLD may be due to its ability to increase lipid β-oxidation and to inhibit the hepatic endoplasmic reticulum (ER) stress. Together, UA may be further considered as a natural compound for NAFLD treatment.

  9. Salinomycin induces cell death with autophagy through activation of endoplasmic reticulum stress in human cancer cells.

    PubMed

    Li, Tianliang; Su, Ling; Zhong, Ning; Hao, Xuexi; Zhong, Diansheng; Singhal, Sunil; Liu, Xiangguo

    2013-07-01

    Salinomycin is perhaps the first promising compound that was discovered through high throughput screening in cancer stem cells. This novel agent can selectively eliminate breast and other cancer stem cells, though the mechanism of action remains unclear. In this study, we found that salinomycin induced autophagy in human non-small cell lung cancer (NSCLC) cells. Furthermore, we demonstrated that salinomycin stimulated endoplasmic reticulum stress and mediated autophagy via the ATF4-DDIT3/CHOP-TRIB3-AKT1-MTOR axis. Moreover, we found that the autophagy induced by salinomycin played a prosurvival role in human NSCLC cells and attenuated the apoptotic cascade. We also showed that salinomycin triggered more apoptosis and less autophagy in A549 cells in which CDH1 expression was inhibited, suggesting that the inhibition of autophagy might represent a promising strategy to target cancer stem cells. In conclusion, these findings provide evidence that combination treatment with salinomycin and pharmacological autophagy inhibitors will be an effective therapeutic strategy for eliminating cancer cells as well as cancer stem cells.

  10. Calcium regulation in mouse mesencephalic neurons-Differential roles of Na(+)/Ca(2+) exchanger, mitochondria and endoplasmic reticulum.

    PubMed

    Wu, Pei-Chun; Kao, Lung-Sen

    2016-06-01

    Midbrain dopaminergic (DA) neurons are the key to finely tune the voluntary movement, habit and motivation. The progressive and selective degeneration of these neurons is a pathological hallmark of Parkinson's disease (PD). The susceptibility of DA neurons in the SNpc may result from differences in how Ca(2+) is handled. However, very little information is available about the mechanisms involved in the regulation of intracellular Ca(2+) concentration ([Ca(2+)]i) in DA neurons. In this study, the relative contributions of various Na(+)/Ca(2+) exchangers and their interplay with internal Ca(2+) stores, endoplasmic reticulum (ER) and the mitochondria, in the regulation of the [Ca(2+)]i of mouse mesencephalic neurons were characterized. Both the K(+)-dependent Na(+)/Ca(2+) exchanger (NCKX) and the K(+)-independent Na(+)/Ca(2+) exchanger (NCX) can be detected and are functional in DA and non-DA neurons. NCX accounts for the larger component of Na(+)/Ca(2+) exchange activity. Single-cell RT-PCR analysis showed each individual neuron expressed a distinct set of the Na(+)/Ca(2+) exchangers. Furthermore, the Na(+)/Ca(2+) exchangers play prominent roles in removing [Ca(2+)]i induced by glutamate but not [Ca(2+)]i induced by depolarization. The mitochondria serve as a major Ca(2+) sink and are functionally located close to NCX. In contrast, the ER is functionally located close to NCKX and acts primarily as a Ca(2+) source with marginal effects. This study reveals that the Na(+)/Ca(2+) exchangers, the ER and the mitochondria, which cooperate interactively, act similarly when regulating [Ca(2+)]i in mesencephalic DA and non-DA neurons. The heterogeneous expression of multiple types of Na(+)/Ca(2+) exchangers and the quantitative differences found in [Ca(2+)]i regulation, together with other risk factors specific to DA neurons such as dopamine oxidation resulting in oxidative stress, may drive these cells to undergo selective degeneration.

  11. Bushen Zhuangjin decoction inhibits TM-induced chondrocyte apoptosis mediated by endoplasmic reticulum stress

    PubMed Central

    LIN, PINGDONG; WENG, XIAPING; LIU, FAYUAN; MA, YUHUAN; CHEN, HOUHUANG; SHAO, XIANG; ZHENG, WENWEI; LIU, XIANXIANG; YE, HONGZHI; LI, XIHAI

    2015-01-01

    Chondrocyte apoptosis triggered by endoplasmic reticulum (ER) stress plays a vital role in the pathogenesis of osteoarthritis (OA). Bushen Zhuangjin decoction (BZD) has been widely used in the treatment of OA. However, the cellular and molecular mechanisms responsible for the inhibitory effects of BZD on chondrocyte apoptosis remain to be elucidated. In the present study, we investigated the effects of BZD on ER stress-induced chondrocyte apoptosis using a chondrocyte in vitro model of OA. Chondrocytes obtained from the articular cartilage of the knee joints of Sprague Dawley (SD) rats were detected by immunohistochemical staining for type II collagen. The ER stress-mediated apoptosis of tunicamycin (TM)-stimulated chondrocytes was detected using 4-phenylbutyric acid (4-PBA). We found that 4-PBA inhibited TM-induced chondrocyte apoptosis, which confirmed the successful induction of chondrocyte apoptosis. BZD enhanced the viability of the TM-stimulated chondrocytes in a dose- and time-dependent manner, as shown by MTT assay. The apoptotic rate and the loss of mitochondrial membrane potential (ΔΨm) of the TM-stimulated chondrocytes treated with BZD was markedly decreased compared with those of chondrocytes not treated with BZD, as shown by 4′,6-diamidino-2-phenylindole (DAPI) staining, Annexin V-FITC binding assay and JC-1 assay. To further elucidate the mechanisms responsible for the inhibitory effects of BZD on TM-induced chondrocyte apoptosis mediated by ER stress, the mRNA and protein expression levels of binding immunoglobulin protein (Bip), X-box binding protein 1 (Xbp1), activating transcription factor 4 (Atf4), C/EBP-homologous protein (Chop), caspase-9, caspase-3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were measured by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. In the TM-stimulated chondrocytes treated with BZD, the mRNA and protein expression levels of Bip, Atf4, Chop, caspase-9, caspase-3

  12. Bushen Zhuangjin decoction inhibits TM-induced chondrocyte apoptosis mediated by endoplasmic reticulum stress.

    PubMed

    Lin, Pingdong; Weng, Xiaping; Liu, Fayuan; Ma, Yuhuan; Chen, Houhuang; Shao, Xiang; Zheng, Wenwei; Liu, Xianxiang; Ye, Hongzhi; Li, Xihai

    2015-12-01

    Chondrocyte apoptosis triggered by endoplasmic reticulum (ER) stress plays a vital role in the pathogenesis of osteoarthritis (OA). Bushen Zhuangjin decoction (BZD) has been widely used in the treatment of OA. However, the cellular and molecular mechanisms responsible for the inhibitory effects of BZD on chondrocyte apoptosis remain to be elucidated. In the present study, we investigated the effects of BZD on ER stress-induced chondrocyte apoptosis using a chondrocyte in vitro model of OA. Chondrocytes obtained from the articular cartilage of the knee joints of Sprague Dawley (SD) rats were detected by immunohistochemical staining for type Ⅱ collagen. The ER stress-mediated apoptosis of tunicamycin (TM)‑stimulated chondrocytes was detected using 4-phenylbutyric acid (4‑PBA). We found that 4‑PBA inhibited TM-induced chondrocyte apoptosis, which confirmed the successful induction of chondrocyte apoptosis. BZD enhanced the viability of the TM-stimulated chondrocytes in a dose- and time-dependent manner, as shown by MTT assay. The apoptotic rate and the loss of mitochondrial membrane potential (ΔΨm) of the TM-stimulated chondrocytes treated with BZD was markedly decreased compared with those of chondrocytes not treated with BZD, as shown by 4',6-diamidino-2-phenylindole (DAPI) staining, Annexin V-FITC binding assay and JC-1 assay. To further elucidate the mechanisms responsible for the inhibitory effects of BZD on TM‑induced chondrocyte apoptosis mediated by ER stress, the mRNA and protein expression levels of binding immunoglobulin protein (Bip), X‑box binding protein 1 (Xbp1), activating transcription factor 4 (Atf4), C/EBP‑homologous protein (Chop), caspase‑9, caspase-3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were measured by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. In the TM-stimulated chondrocytes treated with BZD, the mRNA and protein expression levels of Bip, Atf4, Chop, caspase

  13. Involvement of endoplasmic reticulum stress in formalin-induced pain is attenuated by 4-phenylbutyric acid

    PubMed Central

    Zhou, Fan; Zhang, Wei; Zhou, Jianmei; Li, Meirong; Zhong, Feng; Zhang, Yun; Liu, Yuezhu; Wang, Yaping

    2017-01-01

    Background Endoplasmic reticulum (ER) stress is involved in many neurological and inflammatory responses. Peripheral inflammatory responses can induce central sensitization and trigger inflammatory pain. However, there is little research on the relationship between ER stress and inflammatory pain. In this study, we examined whether the ER stress response is involved in peripheral inflammatory pain using a formalin-induced rat pain model. Methods Rats were divided into the following five groups: control, formalin, formalin + vehicle, formalin + 4-phenylbutyric acid (4-PBA) (40 mg/kg) and formalin + 4-PBA (100 mg/kg). Formalin-induced pain was assessed behaviorally by recording licking activity. The expression levels of immunoglobulin-binding protein (BIP), activating transcription factor-6 (ATF6), phosphorylated inositol-requiring enzyme-1 (p-IRE1), phosphorylated protein kinase RNA-like ER kinase (p-PERK) and c-fos were quantitatively assessed by Western blot, and the distribution of BIP, ATF6 and c-fos in the lumbar enlargement of spinal cord were identified by immunohistochemistry in spinal dorsal horn slices. In addition, the concentrations of nitric oxide (NO) and prostaglandin E2 (PGE2) in the spinal cord were tested by biochemical measurement and enzyme-linked immunosorbent assay (ELISA), respectively. Results Intraperitoneal injection of 4-PBA at the dose of 100 mg/kg before formalin injection significantly decreased nociceptive behavior in the second phase compared with control, formalin, formalin + vehicle and formalin + 4-PBA (40 mg/kg) (P<0.05). Western blot showed that formalin injection significantly upregulated the expression of BIP, ATF6, p-PERK and c-fos in the spinal cord. This upregulation was reduced by peritoneal injection of 4-PBA (P<0.05), while expression of p-IRE1 was not altered by formalin treatment. Immunohistochemistry revealed markedly increased staining density for BIP, ATF6 and c-fos in the superficial spinal dorsal horn after

  14. Endoplasmic Reticulum Stress Signaling in Plant Immunity—At the Crossroad of Life and Death

    PubMed Central

    Kørner, Camilla J.; Du, Xinran; Vollmer, Marie E.; Pajerowska-Mukhtar, Karolina M.

    2015-01-01

    Rapid and complex immune responses are induced in plants upon pathogen recognition. One form of plant defense response is a programmed burst in transcription and translation of pathogenesis-related proteins, of which many rely on ER processing. Interestingly, several ER stress marker genes are up-regulated during early stages of immune responses, suggesting that enhanced ER capacity is needed for immunity. Eukaryotic cells respond to ER stress through conserved signaling networks initiated by specific ER stress sensors tethered to the ER membrane. Depending on the nature of ER stress the cell prioritizes either survival or initiates programmed cell death (PCD). At present two plant ER stress sensors, bZIP28 and IRE1, have been described. Both sensor proteins are involved in ER stress-induced signaling, but only IRE1 has been additionally linked to immunity. A second branch of immune responses relies on PCD. In mammals, ER stress sensors are involved in activation of PCD, but it is unclear if plant ER stress sensors play a role in PCD. Nevertheless, some ER resident proteins have been linked to pathogen-induced cell death in plants. In this review, we will discuss the current understanding of plant ER stress signaling and its cross-talk with immune signaling. PMID:26556351

  15. Proteome-wide study of endoplasmic reticulum stress induced by thapsigargin in N2a neuroblastoma cells.

    PubMed

    Földi, István; Tóth, Anikó M; Szabó, Zoltán; Mózes, Emese; Berkecz, Róbert; Datki, Zsolt L; Penke, Botond; Janáky, Tamás

    2013-01-01

    Disturbances in intraluminal endoplasmic reticulum (ER) Ca(2+) concentration leads to the accumulation of unfolded proteins and perturbation of intracellular Ca(2+) homeostasis, which has a huge impact on mitochondrial functioning under normal and stress conditions and can trigger cell death. Thapsigargin (TG) is widely used to model cellular ER stress as it is a selective and powerful inhibitor of sarcoplasmic/endoplasmic reticulum Ca(2+) ATPases. Here we provide a representative proteome-wide picture of ER stress induced by TG in N2a neuroblastoma cells. Our proteomics study revealed numerous significant protein expression changes in TG-treated N2a cell lysates analysed by two-dimensional electrophoresis followed by mass spectrometric protein identification. The proteomic signature supports the evidence of increased bioenergetic activity of mitochondria as several mitochondrial enzymes with roles in ATP-production, tricarboxylic acid cycle and other mitochondrial metabolic processes were upregulated. In addition, the upregulation of the main ER resident proteins confirmed the onset of ER stress during TG treatment. It has become widely accepted that metabolic activity of mitochondria is induced in the early phases in ER stress, which can trigger mitochondrial collapse and subsequent cell death. Further investigations of this cellular stress response in different neuronal model systems like N2a cells could help to elucidate several neurodegenerative disorders in which ER stress is implicated.

  16. Ursodeoxycholic Acid (UDCA) Exerts Anti-Atherogenic Effects by Inhibiting Endoplasmic Reticulum (ER) Stress Induced by Disturbed Flow.

    PubMed

    Chung, Jihwa; Kim, Kyoung Hwa; Lee, Seok Cheol; An, Shung Hyun; Kwon, Kihwan

    2015-10-01

    Disturbed blood flow with low-oscillatory shear stress (OSS) is a predominant atherogenic factor leading to dysfunctional endothelial cells (ECs). Recently, it was found that disturbed flow can directly induce endoplasmic reticulum (ER) stress in ECs, thereby playing a critical role in the development and progression of atherosclerosis. Ursodeoxycholic acid (UDCA), a naturally occurring bile acid, has long been used to treat chronic cholestatic liver disease and is known to alleviate endoplasmic reticulum (ER) stress at the cellular level. However, its role in atherosclerosis remains unexplored. In this study, we demonstrated the anti-atherogenic activity of UDCA via inhibition of disturbed flow-induced ER stress in atherosclerosis. UDCA effectively reduced ER stress, resulting in a reduction in expression of X-box binding protein-1 (XBP-1) and CEBP-homologous protein (CHOP) in ECs. UDCA also inhibits the disturbed flow-induced inflammatory responses such as increases in adhesion molecules, monocyte adhesion to ECs, and apoptosis of ECs. In a mouse model of disturbed flow-induced atherosclerosis, UDCA inhibits atheromatous plaque formation through the alleviation of ER stress and a decrease in adhesion molecules. Taken together, our results revealed that UDCA exerts anti-atherogenic activity in disturbed flow-induced atherosclerosis by inhibiting ER stress and the inflammatory response. This study suggests that UDCA may be a therapeutic agent for prevention or treatment of atherosclerosis.

  17. Laminin β2 Gene Missense Mutation Produces Endoplasmic Reticulum Stress in Podocytes

    PubMed Central

    Chen, Ying Maggie; Zhou, Yuefang; Go, Gloriosa; Marmerstein, Joseph T.; Kikkawa, Yamato

    2013-01-01

    Mutations in the laminin β2 gene (LAMB2) cause Pierson syndrome, a severe congenital nephrotic syndrome with ocular and neurologic defects. LAMB2 is a component of the laminin-521 (α5β2γ1) trimer, an important constituent of the glomerular basement membrane (GBM). The C321R-LAMB2 missense mutation leads to congenital nephrotic syndrome but only mild extrarenal symptoms; the mechanisms underlying the development of proteinuria with this mutation are unclear. We generated three transgenic mouse lines, in which rat C321R-LAMB2 replaced mouse LAMB2 in the GBM. During the first postnatal month, expression of C321R-LAMB2 attenuated the severe proteinuria exhibited by Lamb2−/− mice in a dose-dependent fashion; proteinuria eventually increased, however, leading to renal failure. The C321R mutation caused defective secretion of laminin-521 from podocytes to the GBM accompanied by podocyte endoplasmic reticulum (ER) stress, likely resulting from protein misfolding. Moreover, ER stress preceded the onset of significant proteinuria and was manifested by induction of the ER-initiated apoptotic signal C/EBP homologous protein (CHOP), ER distention, and podocyte injury. Treatment of cells expressing C321R-LAMB2 with the chemical chaperone taurodeoxycholic acid (TUDCA), which can facilitate protein folding and trafficking, greatly increased the secretion of the mutant LAMB2. Taken together, these results suggest that the mild variant of Pierson syndrome caused by the C321R-LAMB2 mutation may be a prototypical ER storage disease, which may benefit from treatment approaches that target the handling of misfolded proteins. PMID:23723427

  18. High-Density Lipoprotein Prevents Endoplasmic Reticulum Stress-Induced Downregulation of Liver LOX-1 Expression.

    PubMed

    Hong, Dan; Li, Ling-Fang; Gao, Hai-Chao; Wang, Xiang; Li, Chuan-Chang; Luo, Ying; Bai, Yong-Ping; Zhang, Guo-Gang

    2015-01-01

    Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a specific cell-surface receptor for oxidized-low-density lipoprotein (ox-LDL). The impact of high-density lipoprotein (HDL) on endoplasmic reticulum (ER) stress-mediated alteration of the LOX-1 level in hepatocytes remains unclear. We aimed to investigate the impact on LOX-1 expression by tunicamycin (TM)-induced ER stress and to determine the effect of HDL on TM-affected LOX-1 expression in hepatic L02 cells. Overexpression or silencing of related cellular genes was conducted in TM-treated cells. mRNA expression was evaluated using real-time polymerase chain reaction (PCR). Protein expression was analyzed by western blot and immunocytochemistry. Lipid uptake was examined by DiI-ox-LDL, followed by flow cytometric analysis. The results showed that TM induced the upregulation of ER chaperone GRP78, downregulation of LOX-1 expression, and lipid uptake. Knock down of IRE1 or XBP-1 effectively restored LOX-1 expression and improved lipid uptake in TM-treated cells. HDL treatment prevented the negative impact on LOX-1 expression and lipid uptake induced by TM. Additionally, 1-10 μg/mL HDL significantly reduced the GRP78, IRE1, and XBP-1 expression levels in TM-treated cells. Our findings reveal that HDL could prevent the TM-induced reduction of LOX-1 expression via inhibiting the IRE1/XBP-1 pathway, suggesting a new mechanism for beneficial roles of HDL in improving lipid metabolism.

  19. Role of endoplasmic reticulum stress in acrolein-induced endothelial activation

    SciTech Connect

    Haberzettl, Petra; Vladykovskaya, Elena; Srivastava, Sanjay; Bhatnagar, Aruni

    2009-01-01

    Acrolein is a ubiquitous environmental pollutant and an endogenous product of lipid peroxidation. It is also generated during the metabolism of several drugs and amino acids. In this study, we examined the effects of acrolein on endothelial cells. Treatment of human umbilical vein endothelial cells (HUVECs) with 2 to 10 {mu}M acrolein led to an increase in the phosphorylation of eIF-2{alpha} within 10 to 30 min of exposure. This was followed by alternate splicing of XBP-1 mRNA and an increase in the expression of the endoplasmic reticulum (ER) chaperone genes Grp78 and Herp. Within 2-4 h of treatment, acrolein also increased the abundance and the nuclear transport of the transcription factors ATF3, AFT4, and CHOP. Acrolein-induced increase in ATF3 was prevented by treating the cells with the chemical chaperone - phenylbutyric acid (PBA). Treatment with acrolein increased phosphorylation of ERK1/2, p38, and JNK. The increase in JNK phosphorylation was prevented by PBA. Acrolein treatment led to activation and nuclear translocation of the transcription factor NF-{kappa}B and an increase in TNF-{alpha}, IL-6 and IL-8, but not MCP-1, mRNA. Increased expression of cytokine genes and NF-{kappa}B activation were not observed in cells treated with PBA. These findings suggest that exposure to acrolein induces ER stress and triggers the unfolded protein response and that NF-{kappa}B activation and stimulation of cytokine production by acrolein could be attributed, in part, to ER stress. Chemical chaperones of protein-folding may be useful in treating toxicological and pathological states associated with excessive acrolein exposure or production.

  20. Melatonin Activates Endoplasmic Reticulum Stress and Apoptosis in Rats with Diethylnitrosamine-Induced Hepatocarcinogenesis

    PubMed Central

    Moreira, Andrea Janz; Ordoñez, Raquel; Cerski, Carlos Thadeu; Picada, Jaqueline Nascimento; García-Palomo, Andrés; Marroni, Norma Possa; Mauriz, Jose L.; González-Gallego, Javier

    2015-01-01

    Hepatocellular carcinoma (HCC) is one of the most lethal human cancers worldwide because of its high incidence, its metastatic potential and the low efficacy of conventional treatment. Inactivation of apoptosis is implicated in tumour progression and chemotherapy resistance, and has been linked to the presence of endoplasmic reticulum stress. Melatonin, the main product of the pineal gland, exerts anti-proliferative, pro-apoptotic and anti-angiogenic effects in HCC cells, but these effects still need to be confirmed in animal models. Male Wistar rats in treatment groups received diethylnitrosamine (DEN) 50 mg/kg intraperitoneally twice/once a week for 18 weeks. Melatonin was given in drinking water at 1 mg/kg/d, beginning 5 or 12 weeks after the start of DEN administration. Melatonin improved survival rates and successfully attenuated liver injury, as shown by histopathology, decreased levels of serum transaminases and reduced expression of placental glutathione S-transferase. Furthermore, melatonin treatment resulted in a significant increase of caspase 3, 8 and 9 activities, polyadenosine diphosphate (ADP) ribose polymerase (PARP) cleavage, and Bcl-associated X protein (Bax)/Bcl-2 ratio. Cytochrome c, p53 and Fas-L protein concentration were also significantly enhanced by melatonin. Melatonin induced an increased expression of activating transcription factor 6 (ATF6), C/EBP-homologous protein (CHOP) and immunoglobulin heavy chain-binding protein (BiP), while cyclooxygenase (COX)-2 expression decreased. Data obtained suggest that induction of apoptosis and ER stress contribute to the beneficial effects of melatonin in rats with DEN-induced HCC. PMID:26656265

  1. Crocetin prevents retinal degeneration induced by oxidative and endoplasmic reticulum stresses via inhibition of caspase activity.

    PubMed

    Yamauchi, Mika; Tsuruma, Kazuhiro; Imai, Shunsuke; Nakanishi, Tomohiro; Umigai, Naofumi; Shimazawa, Masamitsu; Hara, Hideaki

    2011-01-10

    Crocetin is a carotenoid that is the aglicone of crocin, which are found in saffron stigmas (Crocus sativus L.) and gardenia fruit (Gardenia jasminoides Ellis). In this study, we investigated the effects of crocetin on retinal damage. To examine whether crocetin affects stress pathways, we investigated intracellular oxidation induced by reactive oxygen species, expression of endoplasmic reticulum (ER) stress-related proteins, disruption of the mitochondrial membrane potential (ΔΨ(m)), and caspases activation. In vitro, we employed cultured retinal ganglion cells (RGC-5, a mouse ganglion cell-line transformed using E1A virus). Cell damage was induced by tunicamycin or hydrogen peroxide (H(2)O(2)) exposure. Crocetin at a concentration of 3μM showed the inhibitory effect of 50-60% against tunicamycin- and H(2)O(2)-induced cell death and inhibited increase in caspase-3 and -9 activity. Moreover, crocetin inhibited the enzymatic activity of caspase-9 in a cell-free system. In vivo, retinal damage in mice was induced by exposure to white light at 8000lx for 3h after dark adaptation. Photoreceptor damage was evaluated by measuring the outer nuclear layer thickness at 5days after light exposure and recording the electroretinogram (ERG). Retinal cell damage was also detected with Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining at 48h after light exposure. Crocetin at 100mg/kg, p.o. significantly inhibited photoreceptor degeneration and retinal dysfunction and halved the expression of TUNEL-positive cells. These results indicate that crocetin has protective effects against retinal damage in vitro and in vivo, suggesting that the mechanism may inhibit increase in caspase-3 and -9 activities after retinal damage.

  2. The endoplasmic reticulum stress response is involved in apoptosis induced by aloe-emodin in HK-2 cells.

    PubMed

    Zhu, Shaohua; Jin, Jing; Wang, Yan; Ouyang, Zizhang; Xi, Chen; Li, Jia; Qiu, Yuwen; Wan, Jinzhi; Huang, Min; Huang, Zhiying

    2012-03-01

    Aloe-emodin (AE; 1,8-dihydroxy-3-hydroxymethyl-9,10-anthracenedione) is one of the primary active compounds in total rhubarb anthraquinones (TRAs), which induce nephrotoxicity in rats. However, it is still not known whether AE has a similar effect on human kidney cells. In this study, 3-(4,5,-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays showed that AE decreases the viability of HK-2 cells (a human proximal tubular epithelial cell line) in a dose- and time-dependent manner. AE induced G2/M arrest of cell cycle in HK-2 cells, which was detected with propidium iodide (PI) staining. This apoptosis was further investigated by Hoechst staining, transmission electron microscopy (TEM), DNA fragmentation, and Annexin V/PI staining. Apoptosis of the cells was associated with caspase 3 activation, which was detected by Western blot analysis and a caspase activity assay. In addition, changes in the endoplasmic reticulum (ER) ultrastructure as observed by TEM showed the effects of AE on ER. Treatment with AE also resulted in an increase in eukaryotic initiation factor-2α (eIF-2α) phosphorylation, X-box binding protein 1 (XBP1) mRNA splicing, c-Jun N-terminal kinase (JNK) phosphorylation, glucose-regulated protein (GRP) 78 and CAAT/enhancer-binding protein-homologous protein (CHOP) accumulation. These results suggest that AE induces ER stress in HK-2 cells, which is involved in AE-induced apoptosis. In conclusion, AE induces apoptosis in HK-2 cells, and the ER stress is involved in AE-induced apoptosis in vitro. The implications of the toxic effects of AE for clinical use are unclear and these findings should be taken into account in the risk assessment for human exposure.

  3. Palmitoylethanolamide protects mice against 6-OHDA-induced neurotoxicity and endoplasmic reticulum stress: In vivo and in vitro evidence.

    PubMed

    Avagliano, Carmen; Russo, Roberto; De Caro, Carmen; Cristiano, Claudia; La Rana, Giovanna; Piegari, Giuseppe; Paciello, Orlando; Citraro, Rita; Russo, Emilio; De Sarro, Giovambattista; Meli, Rosaria; Mattace Raso, Giuseppina; Calignano, Antonio

    2016-11-01

    Several pathogenetic factors have been involved in the onset and progression of Parkinson's disease (PD), including inflammation, oxidative stress, unfolded protein accumulation, and apoptosis. Palmitoylethanolamide (PEA), an endogenous N-acylethanolamine, has been shown to be a neuroprotective and anti-inflammatory molecule, acting as a peroxisome proliferator activated receptor (PPAR)-α agonist. In this study we investigated the effects of PEA on behavioral alterations and the underlying pathogenic mechanisms in the 6-hydroxydopamine (6-OHDA)-induced model of PD in male mice. Additionally, we showed the involvement of PPAR-α in PEA protective effect on SH-SY5Y neuroblastoma against 6-OHDA damage. Here, we report that PEA (3-30mg/kg/days.c.) improved behavioral impairments induced by unilateral intrastriatal injection of 6-OHDA. This effect was accompanied by a significant increase in tyrosine hydroxylase expression at striatal level, indicating PEA preserving effect on dopaminergic neurons. Moreover, we found a reduction in the expression of pro-inflammatory enzymes, i.e. inducible nitric oxide synthase and cyclooxygenase-2, a modulation between pro- and anti-apoptotic markers, suggestive of PEA capability in controlling neuroinflammation and cell death. Interestingly, PEA also showed protective scavenging effect, through superoxide dismutase induction, and dampened unfolding protein response, interfering on glucose-regulated protein 78 expression and PERK-eIF2α pathway. Similar data were found in in vitro studies, where PEA treatment was found to rescue SH-SY5Y neuroblastoma cells from 6-OHDA-induced damage and death, partly by inhibiting endoplasmic reticulum stress detrimental response. Therefore, PEA, counteracting the pathogenetic aspects involved in the development of PD, showed its therapeutic potential, possibly integrating current treatments correcting dopaminergic deficits and motor dysfunction.

  4. Realgar quantum dots induce apoptosis and necrosis in HepG2 cells through endoplasmic reticulum stress

    PubMed Central

    QIN, YU; WANG, HUAN; LIU, ZHENG-YUN; LIU, JIE; WU, JIN-ZHU

    2015-01-01

    Realgar (As4S4) has been used in traditional Chinese medicines for treatment of malignancies. However, the poor water solubility of realgar limits its clinical application. To overcome this problem, realgar quantum dots (RQDs; 5.48±1.09 nm) were prepared by a photoluminescence method. The mean particle size was characterized by high-resolution transmission electron microscopy and scanning electron microscopy. Our recent studies revealed that the RQDs were effective against tumor growth in tumor-bearing mice without producing apparent toxicity. The present study investigated their anticancer effects and mechanisms in human hepatocellular carcinoma (HepG2) cells. The HepG2 cells and human normal liver (L02) cells were used to determine the cytotoxicity of RQDs. The portion of apoptotic and dead cells were measured by flow cytometry with Annexin V-fluorescein isothiocyanate/propidium iodide double staining. Apoptosis-related proteins and genes were examined by western blot analysis and reverse transcription-quantitative polymerase chain reaction, and the mitochondrial membrane potential was assayed by confocal microscope with JC-1 as a probe. RQDs exhibited cytotoxicity in a concentration-dependent manner and HepG2 cells were more sensitive compared with normal L02 cells. At 15 µg/ml, 20% of the cells were apoptotic, while 60% of the cells were necrotic at 30 µg/ml. The anti-apoptosis protein Bcl-2 was dose-dependently decreased, while pro-apoptotic protein Bax was increased. There was a loss of mitochondrial membrane potential and expression of the stress genes C/EBP-homologous protein 10 and glucose-regulated protein 78 was increased by RQDs. RQDs were effective in the inhibition of HepG2 cell proliferation and this effect was due to induction of apoptosis and necrosis through endoplasmic reticulum stress. PMID:26405541

  5. Endoplasmic reticulum stress-activated glycogen synthase kinase 3β aggravates liver inflammation and hepatotoxicity in mice with acute liver failure.

    PubMed

    Ren, Feng; Zhou, Li; Zhang, Xiangying; Wen, Tao; Shi, Hongbo; Xie, Bangxiang; Li, Zhuo; Chen, Dexi; Wang, Zheling; Duan, Zhongping

    2015-01-01

    Endoplasmic reticulum stress (ER stress) has been increasingly recognized as an important mechanism in various liver diseases. However, its intrinsic physiological role in acute liver failure (ALF) remains largely undetermined. This study aimed to examine how ER stress orchestrates glycogen synthase kinase 3β (GSK3β) and inflammation to affect ALF. In a murine ALF model induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS), 4-phenylbutyric acid (4-PBA) is to be administered to relieve ER stress. The lethality rate, liver damage, cytokine expression, and the activity of GSK3β were evaluated. How to regulate LPS-induced inflammation and TNF-α-induced hepatocyte apoptosis by ER stress was investigated in vitro. In vivo, ER stress was triggered in the liver with the progression of mice ALF model. ER stress was essential for the development of ALF because ER stress inhibition by 4-PBA ameliorated the liver damage through decreasing liver inflammation and hepatocyte apoptosis. 4-PBA also decreased GSK3β activity in the livers of ALF mice. In vitro, ER stress induced by tunicamycin synergistically increased LPS-triggered pro-inflammatory cytokine induction and promoted the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathway in bone marrow-derived macrophages; moreover, tunicamycin also cooperated with TNF-α to increase hepatocyte apoptosis. ER stress promoted LPS-triggered inflammation depending on GSK3β activation because inhibition of GSK3β by SB216763, the specific inhibitor of GSK3β, resulted in downregulation of pro-inflammatory genes. ER stress contributes to liver inflammation and hepatotoxicity in ALF, particularly by regulating GSK3β, and is therefore a potential therapeutic target for ALF.

  6. Lithocholic acid induces endoplasmic reticulum stress, autophagy and mitochondrial dysfunction in human prostate cancer cells

    PubMed Central

    Gafar, Ahmed A.; Draz, Hossam M.; Goldberg, Alexander A.; Bashandy, Mohamed A.; Bakry, Sayed; Khalifa, Mahmoud A.; AbuShair, Walid; Titorenko, Vladimir I.

    2016-01-01

    Lithocholic acid (LCA) is a secondary bile acid that is selectively toxic to human neuroblastoma, breast and prostate cancer cells, whilst sparing normal cells. We previously reported that LCA inhibited cell viability and proliferation and induced apoptosis and necrosis of androgen-dependent LNCaP and androgen-independent PC-3 human prostate cancer cells. In the present study, we investigated the roles of endoplasmic reticulum (ER) stress, autophagy and mitochondrial dysfunction in the toxicity of LCA in PC-3 and autophagy deficient, androgen-independent DU-145 cells. LCA induced ER stress-related proteins, such as CCAAT-enhancer-binding protein homologous protein (CHOP), and the phosphorylation of eukaryotic initiation factor 2-alpha (p-eIF2α) and c-Jun N-terminal kinases (p-JNK) in both cancer cell-types. The p53 upregulated modulator of apoptosis (PUMA) and B cell lymphoma-like protein 11 (BIM) levels were decreased at overtly toxic LCA concentrations, although PUMA levels increased at lower LCA concentrations in both cell lines. LCA induced autophagy-related conversion of microtubule-associated proteins 1A/1B light chain 3B (LC3BI–LC3BII), and autophagy-related protein ATG5 in PC-3 cells, but not in autophagy-deficient DU-145 cells. LCA (>10 µM) increased levels of reactive oxygen species (ROS) concentration-dependently in PC-3 cells, whereas ROS levels were not affected in DU-145 cells. Salubrinal, an inhibitor of eIF2α dephosphorylation and ER stress, reduced LCA-induced CHOP levels slightly in PC-3, but not DU-145 cells. Salubrinal pre-treatment increased the cytotoxicity of LCA in PC-3 and DU-145 cells and resulted in a statistically significant loss of cell viability at normally non-toxic concentrations of LCA. The late-stage autophagy inhibitor bafilomycin A1 exacerbated LCA toxicity at subtoxic LCA concentrations in PC-3 cells. The antioxidant α-tocotrienol strongly inhibited the toxicity of LCA in PC-3 cells, but not in DU-145 cells. Collectively

  7. Lithocholic acid induces endoplasmic reticulum stress, autophagy and mitochondrial dysfunction in human prostate cancer cells.

    PubMed

    Gafar, Ahmed A; Draz, Hossam M; Goldberg, Alexander A; Bashandy, Mohamed A; Bakry, Sayed; Khalifa, Mahmoud A; AbuShair, Walid; Titorenko, Vladimir I; Sanderson, J Thomas

    2016-01-01

    Lithocholic acid (LCA) is a secondary bile acid that is selectively toxic to human neuroblastoma, breast and prostate cancer cells, whilst sparing normal cells. We previously reported that LCA inhibited cell viability and proliferation and induced apoptosis and necrosis of androgen-dependent LNCaP and androgen-independent PC-3 human prostate cancer cells. In the present study, we investigated the roles of endoplasmic reticulum (ER) stress, autophagy and mitochondrial dysfunction in the toxicity of LCA in PC-3 and autophagy deficient, androgen-independent DU-145 cells. LCA induced ER stress-related proteins, such as CCAAT-enhancer-binding protein homologous protein (CHOP), and the phosphorylation of eukaryotic initiation factor 2-alpha (p-eIF2α) and c-Jun N-terminal kinases (p-JNK) in both cancer cell-types. The p53 upregulated modulator of apoptosis (PUMA) and B cell lymphoma-like protein 11 (BIM) levels were decreased at overtly toxic LCA concentrations, although PUMA levels increased at lower LCA concentrations in both cell lines. LCA induced autophagy-related conversion of microtubule-associated proteins 1A/1B light chain 3B (LC3BI-LC3BII), and autophagy-related protein ATG5 in PC-3 cells, but not in autophagy-deficient DU-145 cells. LCA (>10 µM) increased levels of reactive oxygen species (ROS) concentration-dependently in PC-3 cells, whereas ROS levels were not affected in DU-145 cells. Salubrinal, an inhibitor of eIF2α dephosphorylation and ER stress, reduced LCA-induced CHOP levels slightly in PC-3, but not DU-145 cells. Salubrinal pre-treatment increased the cytotoxicity of LCA in PC-3 and DU-145 cells and resulted in a statistically significant loss of cell viability at normally non-toxic concentrations of LCA. The late-stage autophagy inhibitor bafilomycin A1 exacerbated LCA toxicity at subtoxic LCA concentrations in PC-3 cells. The antioxidant α-tocotrienol strongly inhibited the toxicity of LCA in PC-3 cells, but not in DU-145 cells. Collectively

  8. IL-15 expression increased in response to treadmill running and inhibited endoplasmic reticulum stress in skeletal muscle in rats.

    PubMed

    Yang, Hong-Tao; Luo, Li-Jie; Chen, Wen-Jia; Zhao, Lei; Tang, Chao-Shu; Qi, Yong-Fen; Zhang, Jing

    2015-02-01

    Interleukin 15 (IL-15) has recently been proposed as a circulating myokine involved in glucose uptake and utilization in skeletal muscle. However, the role and mechanism of IL-15 in exercise improving insulin resistance (IR) is unclear. Here, we investigated the alteration in expression of IL-15 and IL-15 receptor α (IL-15Rα) in skeletal muscle during treadmill running in rats with IR induced by a high-fat diet (HFD) and elucidated the mechanism of the anti-IR effects of IL-15. At 20 weeks of HFD, rats showed severe IR, with increased levels of fasting blood sugar and plasma insulin, impaired glucose tolerance, and reduced glucose transport activity. IL-15 immunoreactivity and mRNA level in gastrocnemius muscle were decreased markedly as compared with controls. IL-15Rα protein and mRNA levels in both soleus and gastrocnemius muscle were significantly decreased, which might attenuate the signaling or secretion of IL-15 in muscle. Eight-week treadmill running completely ameliorated HFD-induced IR and reversed the downregulated level of IL-15 and IL-15Rα in skeletal muscle of HFD-fed rats. To investigate whether IL-15 exerts its anti-IR effects directly in muscle, we pre-incubated muscle strips with the endoplasmic reticulum stress (ERS) inducer dithiothreitol (DTT) or tunicamycin (Tm); IL-15 treatment markedly decreased the protein expression of the ERS markers 78-kDa glucose-regulated protein, 94-kDa glucose-regulated protein and C/EBP homologous protein and inhibited ERS induced by DTT or Tm. Therefore, treadmill running promoted skeletal IL-15 and IL-15Rα expression in HFD-induced IR in rats. The inhibitory effect of IL-15 on ERS may be involved in improved insulin sensitivity with exercise training.

  9. Global Mass Spectrometry and Transcriptomics Array Based Drug Profiling Provides Novel Insight into Glucosamine Induced Endoplasmic Reticulum Stress*

    PubMed Central

    Carvalho, Ana Sofia; Ribeiro, Helena; Voabil, Paula; Penque, Deborah; Jensen, Ole N.; Molina, Henrik; Matthiesen, Rune

    2014-01-01

    We investigated the molecular effects of glucosamine supplements, a popular and safe alternative to nonsteroidal anti-inflammatory drugs, for decreasing pain, inflammation, and maintaining healthy joints. Numerous studies have reported an array of molecular effects after glucosamine treatment. We questioned whether the differences in the effects observed in previous studies were associated with the focus on a specific subproteome or with the use of specific cell lines or tissues. To address this question, global mass spectrometry- and transcription array-based glucosamine drug profiling was performed on malignant cell lines from different stages of lymphocyte development. We combined global label-free MS-based protein quantitation with an open search for modifications to obtain the best possible proteome coverage. Our data were largely consistent with previous studies in a variety of cellular models. We mainly observed glucosamine induced O-GlcNAcylation/O-GalNAcylation (O-HexNAcylation); however, we also observed global and local changes in acetylation, methylation, and phosphorylation. For example, our data provides two additional examples of “yin-yang” between phosphorylation and O-HexNAcylation. Furthermore, we mapped novel O-HexNAc sites on GLU2B and calnexin. GLU2B and calnexin are known to be located in the endoplasmic reticulum (ER) and involved in protein folding and quality control. The O-HexNAc sites were regulated by glucosamine treatment and correlated with the up-regulation of the ER stress marker GRP78. The occupancy of O-HexNAc on GLU2B and calnexin sites differed between the cytosolic and nuclear fractions with a higher occupancy in the cytosolic fraction. Based on our data we propose the hypothesis that O-HexNAc either inactivates calnexin and/or targets it to the cytosolic fraction. Further, we hypothesize that O-HexNAcylation induced by glucosamine treatment enhances protein trafficking. PMID:25128556

  10. Interaction between endoplasmic reticulum stress and caspase 8 activation in retrovirus MoMuLV-ts1-infected astrocytes.

    PubMed

    Liu, Na; Scofield, Virginia L; Qiang, Wenan; Yan, Mingshan; Kuang, Xianghong; Wong, Paul K Y

    2006-05-10

    The murine retrovirus, MoMuLV-ts1, induces progressive paralysis and immune deficiency in FVB/N mice. We have reported previously that ts1 infection causes apoptosis in astrocytes via endoplasmic reticulum (ER) and mitochondrial stress (Liu, N., Kuang, X., Kim, H.T., Stoica, G., Qiang, W., Scofield, V.L., Wong, P.K.Y. Wong. 2004. Possible involvement of both endoplasmic reticulum- and mitochondria-dependent pathways in MoMuLV-ts1-induced apoptosis in astrocytes. J. NeuroVirol. 10, 189-198). In the present study, we show that caspase 8 activation in these cells is mediated through ER stress-associated elevation of death receptor DR5 and the C/EBP homologous protein (GADD153/CHOP), an ER stress-initiated transcription factor, rather than through TNFalpha and TNF-R1 interactions on the cell surface. Treatment with Z-IETD-FMK, a specific inhibitor of caspase 8 enzymatic activity, reduced ER stress by two mechanisms: by inhibiting caspase 8 activation, and by preventing cleavage of the ER-associated membrane protein BAP31 into BAP20, which exacerbates the ER stress response. These findings suggest that caspase 8- and ER stress-associated apoptotic pathways are linked in ts1-infected astrocytes.

  11. Cystic Fibrosis Transmembrane Conductance Regulator in Sarcoplasmic Reticulum of Airway Smooth Muscle. Implications for Airway Contractility

    PubMed Central

    Cook, Daniel P.; Rector, Michael V.; Bouzek, Drake C.; Michalski, Andrew S.; Gansemer, Nicholas D.; Reznikov, Leah R.; Li, Xiaopeng; Stroik, Mallory R.; Ostedgaard, Lynda S.; Abou Alaiwa, Mahmoud H.; Thompson, Michael A.; Prakash, Y. S.; Krishnan, Ramaswamy; Meyerholz, David K.; Seow, Chun Y.

    2016-01-01

    Rationale: An asthma-like airway phenotype has been described in people with cystic fibrosis (CF). Whether these findings are directly caused by loss of CF transmembrane conductance regulator (CFTR) function or secondary to chronic airway infection and/or inflammation has been difficult to determine. Objectives: Airway contractility is primarily determined by airway smooth muscle. We tested the hypothesis that CFTR is expressed in airway smooth muscle and directly affects airway smooth muscle contractility. Methods: Newborn pigs, both wild type and with CF (before the onset of airway infection and inflammation), were used in this study. High-resolution immunofluorescence was used to identify the subcellular localization of CFTR in airway smooth muscle. Airway smooth muscle function was determined with tissue myography, intracellular calcium measurements, and regulatory myosin light chain phosphorylation status. Precision-cut lung slices were used to investigate the therapeutic potential of CFTR modulation on airway reactivity. Measurements and Main Results: We found that CFTR localizes to the sarcoplasmic reticulum compartment of airway smooth muscle and regulates airway smooth muscle tone. Loss of CFTR function led to delayed calcium reuptake following cholinergic stimulation and increased myosin light chain phosphorylation. CFTR potentiation with ivacaftor decreased airway reactivity in precision-cut lung slices following cholinergic stimulation. Conclusions: Loss of CFTR alters porcine airway smooth muscle function and may contribute to the airflow obstruction phenotype observed in human CF. Airway smooth muscle CFTR may represent a therapeutic target in CF and other diseases of airway narrowing. PMID:26488271

  12. Function and regulation of sarcoplasmic reticulum Ca2+-ATPase: advances during the past decade and prospects for the coming decade.

    PubMed

    Arai, M

    2000-01-01

    In cardiac muscle, the contraction-relaxation cycle is tightly controlled by the regulated release and uptake of intracellular Ca2+ between sarcoplasmic reticulum and cytoplasm. A major protein controlling Ca2+ cycling is Ca2+-ATPase (SERCA2a) located in the sarcoplasmic reticulum membrane. The function of SERCA2a protein is regulated by the phosphorylatable protein, phospholamban. Phosphorylation of phospholamban releases its inhibitory effect on SERCA2a through direct molecular interaction. Recently, mice whose SERCA2a function is increased (overexpression of the gene) or lost (knock out) were developed. These mice demonstrated that SERCA2a pump levels are a major determinant of cardiac muscle contractility and relaxation. These studies open the prospect that the overexpression of SERCA2a can correct cardiac dysfunction seen in heart failure. Advances in knowledge concerning the function and gene regulation of SERCA2a are discussed in this review.

  13. Stress responses during ageing: molecular pathways regulating protein homeostasis.

    PubMed

    Kyriakakis, Emmanouil; Princz, Andrea; Tavernarakis, Nektarios

    2015-01-01

    The ageing process is characterized by deterioration of physiological function accompanied by frailty and ageing-associated diseases. The most broadly and well-studied pathways influencing ageing are the insulin/insulin-like growth factor 1 signaling pathway and the dietary restriction pathway. Recent studies in diverse organisms have also delineated emerging pathways, which collectively or independently contribute to ageing. Among them the proteostatic-stress-response networks, inextricably affect normal ageing by maintaining or restoring protein homeostasis to preserve proper cellular and organismal function. In this chapter, we survey the involvement of heat stress and endoplasmic reticulum stress responses in the regulation of longevity, placing emphasis on the cross talk between different response mechanisms and their systemic effects. We further discuss novel insights relevant to the molecular pathways mediating these stress responses that may facilitate the development of innovative interventions targeting age-related pathologies such as diabetes, cancer, cardiovascular and neurodegenerative diseases.

  14. Disturbance of endogenous hydrogen sulfide generation and endoplasmic reticulum stress in hippocampus are involved in homocysteine-induced defect in learning and memory of rats.

    PubMed

    Li, Man-Hong; Tang, Ji-Ping; Zhang, Ping; Li, Xiang; Wang, Chun-Yan; Wei, Hai-Jun; Yang, Xue-Feng; Zou, Wei; Tang, Xiao-Qing

    2014-04-01

    Homocysteine (Hcy) is a risk factor for Alzheimer's disease (AD). Hydrogen sulfide (H2S) acts as an endogenous neuromodulator and neuroprotectant. It has been shown that endoplasmic reticulum (ER) stress is involved in the pathological mechanisms of the learning and memory dysfunctions and that H2S exerts its neuroprotective role via suppressing ER stress. In the present work, we explored the effects of intracerebroventricular injection of Hcy on the formation of learning and memory, the generation of endogenous H2S, and the expression of ER stress in the hippocampus of rats. We found that intracerebroventricular injection of Hcy in rats leads to learning and memory dysfunctions in the Morris water maze and novel of object recognition test and decreases in the expression of cystathionine-β-synthase, the major enzyme responsible for endogenous H2S generation, and the generation of endogenous H2S in the hippocampus of rats. We also showed that exposure of Hcy could up-regulate the expressions of glucose-regulated protein 78 (GRP78), CHOP, and cleaved caspase-12, which are the major mark proteins of ER stress, in the hippocampus of rats. Taken together, these results suggest that the disturbance of hippocampal endogenous H2S generation and the increase in ER stress in the hippocampus are related to Hcy-induced defect in learning and memory.

  15. Picosecond pulsed electric fields induce apoptosis in HeLa cells via the endoplasmic reticulum stress and caspase-dependent signaling pathways.

    PubMed

    Chen, Wen-Juan; Xiong, Zheng-Ai; Zhang, Min; Yao, Chen-Guo; Zhao, Zhong-Yong; Hua, Yuan-Yuan; Zhou, Wei

    2013-03-01

    The non-invasive treatment of tumors with preserved fertility holds great promise. The application of pulsed electric field (PEF) is a new biomedical engineering technique for tumor therapy. Picosecond pulsed electric fields (psPEF) can be transferred to target deep tissue non-invasively and precisely; however, research of the biological effects of psPEF on cells is limited. Electric theory predicts that when the pulse duration decreases to nanoseconds and picoseconds, it will mainly affect organelles and lead to intracellular electromanipulations. Previous studies have shown that psPEF targets the mitochondria and induces apoptosis through a mitochondrial-mediated pathway in HeLa cells. The endoplasmic reticulum is also involved in the intrinsic pathways of apoptosis. In the present study, HeLa cells were exposed to psPEF to investigate the underlying mechanisms of apoptosis. MTT assay demonstrated that psPEF displayed strong growth inhibitory effects on HeLa cells. Treatment with psPEF led to marked cell apoptosis and cell cycle arrest at the G2/M phase. In addition, psPEF affected the phosphorylation levels of endoplasmic reticulum sensors and upregulated the expression of glucose-regulated protein 78 (GRP78), glucose-regulated protein 94 (GRP94) and CCAAT enhancer-binding protein (C/EBP) homologous protein (CHOP). These changes were accompanied by the elevation of intracellular Ca2+ concentrations. Furthermore, the activation of caspase-12, -9 and -3, led to the release of cytochrome c, as well as the upregulation of Bax and the downregulation of Bcl-2, as observed in the HeLa cells. Taken together, these data suggest that psPEF is an efficient apoptosis-inducing agent for HeLa cells, which exerts its effects, at least partially, via the endoplasmic reticulum stress and caspase-dependent signaling pathways.

  16. The yeast p5 type ATPase, spf1, regulates manganese transport into the endoplasmic reticulum.

    PubMed

    Cohen, Yifat; Megyeri, Márton; Chen, Oscar C W; Condomitti, Giuseppe; Riezman, Isabelle; Loizides-Mangold, Ursula; Abdul-Sada, Alaa; Rimon, Nitzan; Riezman, Howard; Platt, Frances M; Futerman, Anthony H; Schuldiner, Maya

    2013-01-01

    The endoplasmic reticulum (ER) is a large, multifunctional and essential organelle. Despite intense research, the function of more than a third of ER proteins remains unknown even in the well-studied model organism Saccharomyces cerevisiae. One such protein is Spf1, which is a highly conserved, ER localized, putative P-type ATPase. Deletion of SPF1 causes a wide variety of phenotypes including severe ER stress suggesting that this protein is essential for the normal function of the ER. The closest homologue of Spf1 is the vacuolar P-type ATPase Ypk9 that influences Mn(2+) homeostasis. However in vitro reconstitution assays with Spf1 have not yielded insight into its transport specificity. Here we took an in vivo approach to detect the direct and indirect effects of deleting SPF1. We found a specific reduction in the luminal concentration of Mn(2+) in ∆spf1 cells and an increase following it's overexpression. In agreement with the observed loss of luminal Mn(2+) we could observe concurrent reduction in many Mn(2+)-related process in the ER lumen. Conversely, cytosolic Mn(2+)-dependent processes were increased. Together, these data support a role for Spf1p in Mn(2+) transport in the cell. We also demonstrate that the human sequence homologue, ATP13A1, is a functionally conserved orthologue. Since ATP13A1 is highly expressed in developing neuronal tissues and in the brain, this should help in the study of Mn(2+)-dependent neurological disorders.

  17. Endoplasmic reticulum stress is involved in arsenite-induced oxidative injury in rat brain

    SciTech Connect

    Lin, Anya M.Y.; Chao, P.L.; Fang, S.F.; Chi, C.W.; Yang, C.H.

    2007-10-15

    The mechanism underlying sodium arsenite (arsenite)-induced neurotoxicity was investigated in rat brain. Arsenite was locally infused in the substantia nigra (SN) of anesthetized rat. Seven days after infusion, lipid peroxidation in the infused SN was elevated and dopamine level in the ipsilateral striatum was reduced in a concentration-dependent manner (0.3-5 nmol). Furthermore, local infusion of arsenite (5 nmol) decreased GSH content and increased expression of heat shock protein 70 and heme oxygenase-1 in the infused SN. Aggregation of {alpha}-synuclein, a putative pathological protein involved in several CNS neurodegenerative diseases, was elevated in the arsenite-infused SN. From the breakdown pattern of {alpha}-spectrin, both necrosis and apoptosis were involved in the arsenite-induced neurotoxicity. Pyknotic nuclei, cellular shrinkage and cytoplasmic disintegration, indicating necrosis, and TUNEL-positive cells and DNA ladder, indicating apoptosis was observed in the arsenite-infused SN. Arsenite-induced apoptosis was mediated via two different organelle pathways, mitochondria and endoplasmic reticulum (ER). For mitochondrial activation, cytosolic cytochrome c and caspase-3 levels were elevated in the arsenite-infused SN. In ER pathway, arsenite increased activating transcription factor-4, X-box binding protein 1, C/EBP homologues protein (CHOP) and cytosolic immunoglobulin binding protein levels. Moreover, arsenite reduced procaspase 12 levels, an ER-specific enzyme in the infused SN. Taken together, our study suggests that arsenite is capable of inducing oxidative injury in CNS. In addition to mitochondria, ER stress was involved in the arsenite-induced apoptosis. Arsenite-induced neurotoxicity clinically implies a pathophysiological role of arsenite in CNS neurodegeneration.

  18. The Monoterpene Carvacrol Generates Endoplasmic Reticulum Stress in the Pathogenic Fungus Candida albicans.

    PubMed

    Chaillot, Julien; Tebbji, Faiza; Remmal, Adnane; Boone, Charlie; Brown, Grant W; Bellaoui, Mohammed; Sellam, Adnane

    2015-08-01

    The monoterpene carvacrol, the major component of oregano and thyme oils, is known to exert potent antifungal activity against the pathogenic yeast Candida albicans. This monoterpene has been the subject of a considerable number of investigations that uncovered extensive pharmacological properties, including antifungal and antibacterial effects. However, its mechanism of action remains elusive. Here, we used integrative chemogenomic approaches, including genome-scale chemical-genetic and transcriptional profiling, to uncover the mechanism of action of carvacrol associated with its antifungal property. Our results clearly demonstrated that fungal cells require the unfolded protein response (UPR) signaling pathway to resist carvacrol. The mutants most sensitive to carvacrol in our genome-wide competitive fitness assay in the yeast Saccharomyces cerevisiae expressed mutations of the transcription factor Hac1 and the endonuclease Ire1, which is required for Hac1 activation by removing a nonconventional intron from the 3' region of HAC1 mRNA. Confocal fluorescence live-cell imaging revealed that carvacrol affects the morphology and the integrity of the endoplasmic reticulum (ER). Transcriptional profiling of pathogenic yeast C. albicans cells treated with carvacrol demonstrated a bona fide UPR transcriptional signature. Ire1 activity detected by the splicing of HAC1 mRNA in C. albicans was activated by carvacrol. Furthermore, carvacrol was found to potentiate antifungal activity of the echinocandin antifungal caspofungin and UPR inducers dithiothreitol and tunicamycin against C. albicans. This comprehensive chemogenomic investigation demonstrated that carvacrol exerts its antifungal activity by altering ER integrity, leading to ER stress and the activation of the UPR to restore protein-folding homeostasis.

  19. The Monoterpene Carvacrol Generates Endoplasmic Reticulum Stress in the Pathogenic Fungus Candida albicans

    PubMed Central

    Chaillot, Julien; Tebbji, Faiza; Remmal, Adnane; Boone, Charlie; Brown, Grant W.

    2015-01-01

    The monoterpene carvacrol, the major component of oregano and thyme oils, is known to exert potent antifungal activity against the pathogenic yeast Candida albicans. This monoterpene has been the subject of a considerable number of investigations that uncovered extensive pharmacological properties, including antifungal and antibacterial effects. However, its mechanism of action remains elusive. Here, we used integrative chemogenomic approaches, including genome-scale chemical-genetic and transcriptional profiling, to uncover the mechanism of action of carvacrol associated with its antifungal property. Our results clearly demonstrated that fungal cells require the unfolded protein response (UPR) signaling pathway to resist carvacrol. The mutants most sensitive to carvacrol in our genome-wide competitive fitness assay in the yeast Saccharomyces cerevisiae expressed mutations of the transcription factor Hac1 and the endonuclease Ire1, which is required for Hac1 activation by removing a nonconventional intron from the 3′ region of HAC1 mRNA. Confocal fluorescence live-cell imaging revealed that carvacrol affects the morphology and the integrity of the endoplasmic reticulum (ER). Transcriptional profiling of pathogenic yeast C. albicans cells treated with carvacrol demonstrated a bona fide UPR transcriptional signature. Ire1 activity detected by the splicing of HAC1 mRNA in C. albicans was activated by carvacrol. Furthermore, carvacrol was found to potentiate antifungal activity of the echinocandin antifungal caspofungin and UPR inducers dithiothreitol and tunicamycin against C. albicans. This comprehensive chemogenomic investigation demonstrated that carvacrol exerts its antifungal activity by altering ER integrity, leading to ER stress and the activation of the UPR to restore protein-folding homeostasis. PMID:26014932

  20. The regulation of thapsigargin-sensitive sarcoendoplasmic reticulum Ca(2+)-ATPase activity in estivation.

    PubMed

    Ramnanan, Christopher J; Storey, Kenneth B

    2008-01-01

    Estivation (aerobic dormancy) is characterized by sustained metabolic rate depression, which is crucial to survival in the face of unfavorable environmental conditions and enables the preservation of endogenous fuel reserves. Ion pumping is one of the most energetically taxing physiological processes in cells, and ion motive ATPases are likely loci to be differentially regulated in models of metabolic arrest. We proposed that the sarcoendoplasmic reticulum (SER) calcium-ATPase (SERCA) would be deactivated in the estivating desert snail Otala lactea, potentially contributing to the overall suppression of metabolism. SERCA kinetic parameters [decreased maximal velocities, increased substrate K (m) values, increased Arrhenius activation energy (E (a))] were indicative of a less active enzyme in the estivated state. Interestingly, the less active SERCA population in dormant snails featured greater kinetic (K (m) Mg.ATP versus temperature) and conformational (resistance to urea denaturation) stability than that in active snails. Western blotting confirmed that SERCA protein content did not change during estivation. In light of this observation, we proposed that estivation-dependent changes in SERCA activity was due to changes in SERCA phosphorylation state. In vitro studies promoting specific kinase or phosphatase action indicated that decreased SERCA activity in estivation was linked with endogenous kinase activity whereas reactivation of SERCA was facilitated by endogenous protein phosphatases (PP).

  1. The Rate-limiting Enzyme in Phosphatidylcholine Synthesis Regulates Proliferation of the Nucleoplasmic ReticulumD⃞

    PubMed Central

    Lagace, Thomas A.; Ridgway, Neale D.

    2005-01-01

    The nucleus contains a network of tubular invaginations of the nuclear envelope (NE), termed the nucleoplasmic reticulum (NR), implicated in transport, gene expression, and calcium homeostasis. Here, we show that proliferation of the NR, measured by the frequency of NE invaginations and tubules, is regulated by CTP:phosphocholine cytidylyltransferase-α (CCTα), the nuclear and rate-limiting enzyme in the CDP–choline pathway for phosphatidylcholine (PtdCho) synthesis. In Chinese hamster ovary (CHO)-K1 cells, fatty acids triggered activation and translocation of CCTα onto intranuclear tubules characteristic of the NR. This was accompanied by a twofold increase in NR tubules quantified by immunostaining for lamin A/C or the NE. CHO MT58 cells expressing a temperature-sensitive CCTα allele displayed reduced PtdCho synthesis and CCTα expression and minimal proliferation of the NR in response to oleate compared with CHO MT58 cells stably expressing CCTα. Expression of CCTα mutants in CHO58 cells revealed that both enzyme activity and membrane binding promoted NR proliferation. In support of a direct role for membrane binding in NR tubule formation, recombinant CCTα caused the deformation of liposomes into tubules in vitro. This demonstrates that a key nuclear enzyme in PtdCho synthesis coordinates lipid synthesis and membrane deformation to promote formation of a dynamic nuclear-cytoplasmic interface. PMID:15635091

  2. Dithiothreitol enhanced arsenic-trioxide-induced cell apoptosis in cultured oral cancer cells via mitochondrial dysfunction and endoplasmic reticulum stress.

    PubMed

    Tsai, Chia-Wen; Yang, Mei-Due; Hsia, Te-Chun; Chang, Wen-Shin; Hsu, Chin-Mu; Hsieh, Yi-Hsien; Chung, Jing-Gung; Bau, Da-Tian

    2017-01-01

    Arsenic is naturally occurring toxic metalloid and drinking As2 O3 containing water are recognized to be related to increased risk of neurotoxicity, liver injury, blackfoot disease, hypertension, and cancer. On the contrary, As2 O3 has been an ancient drug used in traditional Chinese medicine with substantial anticancer activities, especially in the treatment of acute promyelocytic leukemia as well as chronic wound healing. However, the cytotoxicity and detail mechanisms of As2 O3 action in solid cancer cells, such as oral cancer cells, are largely unknown. In this study, we have primarily cultured four pairs of tumor and nontumor cells from the oral cancer patients and treated the cells with As2 O3 alone or combined with dithiothreitol (DTT). The results showed that 0.5 μM As2 O3 plus 20 μM DTT caused a significant cell death of oral cancer cells but not the nontumor cells. Also As2 O3 plus DTT upregulated Bax and Bak, downregulated Bcl-2 and p53, caused a loss of mitochondria membrane potential in oral cancer cells. On the other way, As2 O3 also triggered endoplasmic reticulum stress and increased the levels of glucose-regulated protein 78, calpain 1 and 2. Our results suggest that DTT could synergistically enhance the effects of As2 O3 on killing oral cancer cells while nontoxic to the nontumor cells. The combination is promising for clinical practice in oral cancer therapy and worth further investigations. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 17-27, 2017.

  3. The protective effect of lycopene on hypoxia/reoxygenation-induced endoplasmic reticulum stress in H9C2 cardiomyocytes.

    PubMed

    Gao, Yang; Jia, Pengyu; Shu, WenQi; Jia, Dalin

    2016-03-05

    Nowadays, drugs protecting ischemia/reperfusion (I/R) myocardium become more suitable for clinic. It has been confirmed lycopene has various protections, but lacking the observation of its effect on endoplasmic reticulum stress (ERS)-mediated apoptosis caused by hypoxia/reoxygenation (H/R). This study aims to clarify the protective effect of lycopene on ERS induced by H/R in H9C2 cardiomyocytes. Detect the survival rate, lactic dehydrogenase (LDH) activity, apoptosis ratio, glucose-regulated proteins 78 (GRP78), C/EBP homologous protein (CHOP), c-Jun-N-terminal protein Kinase (JNK) and Caspase-12 mRNA and protein expression and phosphorylation of JNK (p-JNK) protein expression. LDH activity, apoptosis ratio and GRP78 protein expression increase in the H/R group, reduced by lycopene. The survival rate reduces in the H/R and thapsigargin (TG) groups; lycopene and 4-phenyl butyric acid (4-PBA) can improve it caused by H/R, lycopene also can improve it caused by TG. The apoptosis ratio, the expression of GRP78, CHOP and Caspase-12 mRNA and protein and p-JNK protein increase in the H/R and TG groups, weaken in the lycopene+H/R, 4-PBA+H/R and lycopene+TG groups. There is no obvious change in the expression of JNK mRNA or protein. Hence, our results provide the evidence that 10 μM lycopene plays an obviously protective effect on H/R H9C2 cardiomyocytes, realized through reducing ERS and apoptosis. The possible mechanism may be related to CHOP, p-JNK and Caspase-12 pathways.

  4. Endoplasmic reticulum stress in mice increases hepatic expression of genes carrying a premature termination codon via a nutritional status-independent GRP78-dependent mechanism.

    PubMed

    Harada, Nagakatsu; Okuyama, Maiko; Yoshikatsu, Aya; Yamamoto, Hironori; Ishiwata, Saori; Hamada, Chikako; Hirose, Tomoyo; Shono, Masayuki; Kuroda, Masashi; Tsutsumi, Rie; Takeo, Jiro; Taketani, Yutaka; Nakaya, Yutaka; Sakaue, Hiroshi

    2017-04-06

    Nonsense-mediated mRNA decay (NMD) degrades mRNAs carrying a premature termination codon (PTC) in eukaryotes. Cellular stresses, including endoplasmic reticulum (ER) stress, inhibit NMD and up-regulate PTC-containing mRNA (PTC-mRNA) levels in several cell lines. However, whether similar effects exist under in vivo conditions that involve systemic nutritional status is unclear. Here we compared the effects of pharmacological induction of ER stress with those of nutritional interventions on hepatic PTC-mRNA levels in mice. In mouse livers, the ER stress inducer tunicamycin increased PTC-mRNA levels of endogenous marker genes. Tunicamycin decreased body weight and perturbed nutrient metabolism in mice. Food restriction or deprivation mimicked the effect of tunicamycin on weight loss and metabolism, but did not increase PTC-mRNA levels. Hyperphagia-induced obesity also had little effect on hepatic PTC-mRNA levels. Meanwhile, in mouse liver phosphorylation of eIF2α, a factor that regulates NMD, was increased by both tunicamycin and nutritional interventions. Hepatic expression of GRP78, a central chaperone in ER stress responses, was increased by tunicamycin but not by the nutritional interventions. In cultured liver cells (Hepa), exogenous overexpression of a phosphomimetic eIF2α failed to increase PTC-mRNA levels. However, GRP78 overexpression in Hepa cells increased PTC-mRNA and PTC-mRNA-derived protein levels. ER stress promoted localization of GRP78 to mitochondria, and exogenous expression of a GRP78 fusion protein targeted to mitochondria mimicked the effect of wild type GRP78. These results indicate that GRP78, but not nutritional status, is a potent up-regulator of hepatic PTC-mRNA levels during induction of ER stress in vivo. This article is protected by copyright. All rights reserved.

  5. Stress response in the ascidian Ciona intestinalis: transcriptional profiling of genes for the heat shock protein 70 chaperone system under heat stress and endoplasmic reticulum stress.

    PubMed

    Fujikawa, Tetsuya; Munakata, Takeo; Kondo, Shin-ichi; Satoh, Nori; Wada, Shuichi

    2010-03-01

    The genome of Ciona intestinalis contains eight genes for HSP70 superfamily proteins, 36 genes for J-proteins, a gene for a J-like protein, and three genes for BAG family proteins. To understand the stress responses of genes in the HSP70 chaperone system comprehensively, the transcriptional profiles of these 48 genes under heat stress and endoplasmic reticulum (ER) stress were studied using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Heat stress treatment increased the messenger RNA (mRNA) levels of six HSP70 superfamily genes, eight J-protein family genes, and two BAG family genes. In the cytoplasmic group of the DnaK subfamily of the HSP70 family, Ci-HSPA1/6/7-like was the only heat-inducible gene and Ci-HSPA2/8 was the only constitutively active gene which showed striking simplicity in comparison with other animals that have been examined genome-wide so far. Analyses of the time course and temperature dependency of the heat stress responses showed that the induction of Ci-HSPA1/6/7-like expression rises to a peak after heat stress treatment at 28 degrees C (10 degrees C upshift from control temperature) for 1 h. ER stress treatment with Brefeldin A, a drug that is known to act as ER stress inducer, increased the mRNA levels of four HSP70 superfamily genes and four J-protein family genes. Most stress-inducible genes are conserved between Ciona and vertebrates, as expected from a close evolutionary relationship between them. The present study characterized the stress responses of HSP70 chaperone system genes in Ciona for the first time and provides essential data for comprehensive understanding of the functions of the HSP70 chaperone system.

  6. Deletion of an Endoplasmic Reticulum Stress Response Element in a ZmPP2C-A Gene Facilitates Drought Tolerance of Maize Seedlings.

    PubMed

    Xiang, Yanli; Sun, Xiaopeng; Gao, Shan; Qin, Feng; Dai, Mingqiu

    2017-03-06

    Drought is a major abiotic stress that causes the yearly yield loss of maize, a crop cultured worldwide. Breeding drought-tolerant maize cultivars is a priority requirement of world agriculture. Clade A PP2C phosphatases (PP2C-A), which are conserved in most plant species, play important roles in abscisic acid (ABA) signaling and plant drought response. However, natural variations of PP2C-A genes that are directly associated with drought tolerance remain to be elucidated. Here, we conducted a candidate gene association analysis of the ZmPP2C-A gene family in a maize panel consisting of 368 varieties collected worldwide, and identified a drought responsive gene ZmPP2C-A10 that is tightly associated with drought tolerance. We found that the degree of drought tolerance of maize cultivars negatively correlates with the expression levels of ZmPP2C-A10. ZmPP2C-A10, like its Arabidopsis orthologs, interacts with ZmPYL ABA receptors and ZmSnRK2 kinases, suggesting that ZmPP2C-A10 is involved in mediating ABA signaling in maize. Transgenic studies in maize and Arabidopsis confirmed that ZmPP2C-A10 functions as a negative regulator of drought tolerance. Further, a causal natural variation, deletion allele-338, which bears a deletion of ERSE (endoplasmic reticulum stress response element) in the 5'-UTR region of ZmPP2C-A10, was detected. This deletion causes the loss of endoplasmic reticulum (ER) stress-induced expression of ZmPP2C-A10, leading to increased plant drought tolerance. Our study provides direct evidence linking ER stress signaling with drought tolerance and genetic resources that can be used directly in breeding drought-tolerant maize cultivars.

  7. Sirtuin1 protects endothelial Caveolin-1 expression and preserves endothelial function via suppressing miR-204 and endoplasmic reticulum stress

    PubMed Central

    Kassan, M.; Vikram, A.; Kim, Y. R.; Li, Q.; Kassan, A.; Patel, H. H.; Kumar, S.; Gabani, M.; Liu, J.; Jacobs, J. S.; Irani, K.

    2017-01-01

    Sirtuin1 (Sirt1) is a class III histone deacetylase that regulates a variety of physiological processes, including endothelial function. Caveolin1 (Cav1) is also an important determinant of endothelial function. We asked if Sirt1 governs endothelial Cav1 and endothelial function by regulating miR-204 expression and endoplasmic reticulum (ER) stress. Knockdown of Sirt1 in endothelial cells, and in vivo deletion of endothelial Sirt1, induced endothelial ER stress and miR-204 expression, reduced Cav1, and impaired endothelium-dependent vasorelaxation. All of these effects were reversed by a miR-204 inhibitor (miR-204 I) or with overexpression of Cav1. A miR-204 mimic (miR-204 M) decreased Cav1 in endothelial cells. In addition, high-fat diet (HFD) feeding induced vascular miR-204 and reduced endothelial Cav1. MiR-204-I protected against HFD-induced downregulation of endothelial Cav1. Moreover, pharmacologic induction of ER stress with tunicamycin downregulated endothelial Cav1 and impaired endothelium-dependent vasorelaxation that was rescued by overexpressing Cav1. In conclusion, Sirt1 preserves Cav1-dependent endothelial function by mitigating miR-204-mediated vascular ER stress. PMID:28181559

  8. Lipocalin 2, a new GADD153 target gene, as an apoptosis inducer of endoplasmic reticulum stress in lung cancer cells

    SciTech Connect

    Hsin, I-Lun; Hsiao, Yueh-Chieh; Wu, Ming-Fang; Jan, Ming-Shiou; Tang, Sheau-Chung; Lin, Yu-Wen; Hsu, Chung-Ping; Ko, Jiunn-Liang

    2012-09-15

    Endoplasmic reticulum (ER) stress is activated under severe cellular conditions. GADD153, a member of the C/EBP family, is an unfolded protein response (UPR) responsive transcription factor. Increased levels of lipocalin 2, an acute phase protein, have been found in several epithelial cancers. The aim of this study is to investigate the function of lipocalin 2 in lung cancer cells under ER stress. Treatment with thapsigargin, an ER stress activator, led to increases in cytotoxicity, ER stress, apoptosis, and lipocalin 2 expression in A549 cells. GADD153 silencing decreased lipocalin 2 expression in A549 cells. On chromatin immunoprecipitation assay, ER stress increased GADD153 DNA binding to lipocalin 2 promoter. Furthermore, silencing of lipocalin 2 mitigated ER stress-mediated apoptosis in A549 cells. Our findings demonstrated that lipocalin 2 is a new GADD153 target gene that mediates ER stress-induced apoptosis. Highlights: ► We demonstrate that Lipocalin 2 is a new GADD153 target gene. ► Lipocalin 2 mediates ER stress-induced apoptosis. ► ER stress-induced lipocalin 2 expression is calcium-independent in A549 cells. ► Lipocalin 2 dose not play a major role in ER stress-induced autophagy.

  9. Nuclear receptor LRH-1/NR5A2 is required and targetable for liver endoplasmic reticulum stress resolution

    PubMed Central

    Mamrosh, Jennifer L; Lee, Jae Man; Wagner, Martin; Stambrook, Peter J; Whitby, Richard J; Sifers, Richard N; Wu, San-Pin; Tsai, Ming-Jer; DeMayo, Francesco J; Moore, David D

    2014-01-01

    Chronic endoplasmic reticulum (ER) stress results in toxicity that contributes to multiple human disorders. We report a stress resolution pathway initiated by the nuclear receptor LRH-1 that is independent of known unfolded protein response (UPR) pathways. Like mice lacking primary UPR components, hepatic Lrh-1-null mice cannot resolve ER stress, despite a functional UPR. In response to ER stress, LRH-1 induces expression of the kinase Plk3, which phosphorylates and activates the transcription factor ATF2. Plk3-null mice also cannot resolve ER stress, and restoring Plk3 expression in Lrh-1-null cells rescues ER stress resolution. Reduced or heightened ATF2 activity also sensitizes or desensitizes cells to ER stress, respectively. LRH-1 agonist treatment increases ER stress resistance and decreases cell death. We conclude that LRH-1 initiates a novel pathway of ER stress resolution that is independent of the UPR, yet equivalently required. Targeting LRH-1 may be beneficial in human disorders associated with chronic ER stress. DOI: http://dx.doi.org/10.7554/eLife.01694.001 PMID:24737860

  10. Modulatory effects of resveratrol on endoplasmic reticulum stress-associated apoptosis and oxido-inflammatory markers in a rat model of rotenone-induced Parkinson's disease.

    PubMed

    Gaballah, Hanaa Hibishy; Zakaria, Soha Said; Elbatsh, Maha M; Tahoon, Nahid M

    2016-05-05

    The mechanisms leading to neuronal death in Parkinson's disease (PD) are not fully elucidated; however, mounting evidence implicates endoplasmic reticulum (ER) stress, oxidative damage, and inflammatory changes are the crucial factors in its pathogenesis. This study was undertaken to investigate the modulatory effects of resveratrol on ER stress-mediated apoptosis, inflammatory and oxidative stress markers in a rat model of rotenone-induced PD. mRNA expression levels of ER stress markers; C/EBP homologous protein (CHOP) and glucose-regulated protein 78 (GRP78), were estimated in the rat brain using quantitative real-time PCR. Caspase-3 activity, IL-1β levels and Nuclear Factor Erythroid 2-related factor (Nrf2) DNA-binding activity were estimated by ELISA, while glutathione peroxidase and Xanthine oxidase activities, as well as protein carbonyl contents in the rat brain were evaluated spectrophotometrically. Our data revealed that Resveratrol ameliorated rotenone-induced ER stress by downregulating CHOP and GRP78 genes expression and hampered caspase-3 activity in the brain of rotenone exposed rats. It also restored redox balance as evident by suppressing Xanthine oxidase activity and protein carbonyls formation; in addition to preservation of intracellular antioxidants status via activating glutathione peroxidase and Nrf2 signaling pathway. In conclusion; our study launched promising avenues for the potential use of resveratrol as a neuroprotective therapeutic agent in Parkinson's disease.

  11. Inhibition of Endoplasmic Reticulum Stress is Involved in the Neuroprotective Effect of bFGF in the 6-OHDA-Induced Parkinson’s Disease Model

    PubMed Central

    Cai, Pingtao; Ye, Jingjing; Zhu, Jingjing; Liu, Dan; Chen, Daqing; Wei, Xiaojie; Johnson, Noah R.; Wang, Zhouguang; Zhang, Hongyu; Cao, Guodong; Xiao, Jian; Ye, Junming; Lin, Li

    2016-01-01

    Parkinson's disease (PD) is a progressive neurodegenerative disorder with complicated pathophysiologic mechanisms. Endoplasmic reticulum (ER) stress appears to play a critical role in the progression of PD. We demonstrated that basic fibroblast growth factor (bFGF), as a neurotropic factor, inhibited ER stress-induced neuronal cell apoptosis and that 6-hydroxydopamine (6-OHDA)-induced ER stress was involved in the progression of PD in rats. bFGF administration improved motor function recovery, increased tyrosine hydroxylase (TH)-positive neuron survival, and upregulated the levels of neurotransmitters in PD rats. The 6-OHDA-induced ER stress response proteins were inhibited by bFGF treatment. Meanwhile, bFGF also increased expression of TH. The administration of bFGF activated the downstream signals PI3K/Akt and Erk1/2 in vivo and in vitro. Inhibition of the PI3K/Akt and Erk1/2 pathways by specific inhibitors partially reduced the protective effect of bFGF. This study provides new insight towards bFGF translational drug development for PD involving the regulation of ER stress. PMID:27493838

  12. HIV-1 Tat Induces Unfolded Protein Response and Endoplasmic Reticulum Stress in Astrocytes and Causes Neurotoxicity through Glial Fibrillary Acidic Protein (GFAP) Activation and Aggregation.

    PubMed

    Fan, Yan; He, Johnny J

    2016-10-21

    HIV-1 Tat is a major culprit for HIV/neuroAIDS. One of the consistent hallmarks of HIV/neuroAIDS is reactive astrocytes or astrocytosis, characterized by increased cytoplasmic accumulation of the intermediate filament glial fibrillary acidic protein (GFAP). We have shown that that Tat induces GFAP expression in astrocytes and that GFAP activation is indispensable for astrocyte-mediated Tat neurotoxicity. However, the underlying molecular mechanisms are not known. In this study, we showed that Tat expression or GFAP expression led to formation of GFAP aggregates and induction of unfolded protein response (UPR) and endoplasmic reticulum (ER) stress in astrocytes. In addition, we demonstrated that GFAP up-regulation and aggregation in astrocytes were necessary but also sufficient for UPR/ER stress induction in Tat-expressing astrocytes and for astrocyte-mediated Tat neurotoxicity. Importantly, we demonstrated that inhibition of Tat- or GFAP-induced UPR/ER stress by the chemical chaperone 4-phenylbutyrate significantly alleviated astrocyte-mediated Tat neurotoxicity in vitro and in the brain of Tat-expressing mice. Taken together, these results show that HIV-1 Tat expression leads to UPR/ER stress in astrocytes, which in turn contributes to astrocyte-mediated Tat neurotoxicity, and raise the possibility of developing HIV/neuroAIDS therapeutics targeted at UPR/ER stress.

  13. The Yeast P5 Type ATPase, Spf1, Regulates Manganese Transport into the Endoplasmic Reticulum

    PubMed Central

    Cohen, Yifat; Megyeri, Márton; Chen, Oscar C. W.; Condomitti, Giuseppe; Riezman, Isabelle; Loizides-Mangold, Ursula; Abdul-Sada, Alaa; Rimon, Nitzan; Riezman, Howard; Platt, Frances M.; Futerman, Anthony H.; Schuldiner, Maya

    2013-01-01

    The endoplasmic reticulum (ER) is a large, multifunctional and essential organelle. Despite intense research, the function of more than a third of ER proteins remains unknown even in the well-studied model organism Saccharomyces cerevisiae. One such protein is Spf1, which is a highly conserved, ER localized, putative P-type ATPase. Deletion of SPF1 causes a wide variety of phenotypes including severe ER stress suggesting that this protein is essential for the normal function of the ER. The closest homologue of Spf1 is the vacuolar P-type ATPase Ypk9 that influences Mn2+ homeostasis. However in vitro reconstitution assays with Spf1 have not yielded insight into its transport specificity. Here we took an in vivo approach to detect the direct and indirect effects of deleting SPF1. We found a specific reduction in the luminal concentration of Mn2+ in ∆spf1 cells and an increase following it’s overexpression. In agreement with the observed loss of luminal Mn2+ we could observe concurrent reduction in many Mn2+-related process in the ER lumen. Conversely, cytosolic Mn2+-dependent processes were increased. Together, these data support a role for Spf1p in Mn2+ transport in the cell. We also demonstrate that the human sequence homologue, ATP13A1, is a functionally conserved orthologue. Since ATP13A1 is highly expressed in developing neuronal tissues and in the brain, this should help in the study of Mn2+-dependent neurological disorders. PMID:24392018

  14. Taurine protects cisplatin induced cardiotoxicity by modulating inflammatory and endoplasmic reticulum stress responses.

    PubMed

    Chowdhury, Sayantani; Sinha, Krishnendu; Banerjee, Sharmistha; Sil, Parames C

    2016-11-12

    Oxidative stress, ER stress, inflammation, and apoptosis results in the pathogenesis of cisplatin-induced cardiotoxicity. The present study was designed to investigate the signaling mechanisms involved in the ameliorating effect of taurine, a conditionally essential amino acid, against cisplatin-mediated cardiac ER stress dependent apoptotic death and inflammation. Mice were simultaneously treated with taurine (150 mg kg(-1) body wt, i.p.) and cisplatin (10 mg kg(-1) body wt, i.p.) for a week. Cisplatin exposure significantly altered serum creatine kinase and troponin T levels. In addition, histological studies revealed disintegration in the normal radiation pattern of cardiac muscle fibers. However, taurine administration could abate such adverse effects of cisplatin. Taurine administration significantly mitigated the reactive oxygen species production, alleviated the overexpression of nuclear factor-κB (NF-κB), and inhibited the elevation of proinflammatoy cytokines, adhesion molecules, and chemokines. Cisplatin exposure resulted in the unfolded protein response (UPR)-regulated CCAAT/enhancer binding protein (CHOP) up-regulation, induction of GRP78: a marker of ER stress and eIF2α signaling. Increase in calpain-1 expression level, activation of caspase-12 and caspase-3, cleavage of the PARP protein as well as the inhibition of antiapoptotic protein Bcl-2 were reflected on cisplatin-triggered apoptosis. Taurine could, however, combat against such cisplatin induced cardiac-abnormalities. The above mentioned findings suggest that taurine plays a beneficial role in providing protection against cisplatin-induced cardiac damage by modulating inflammatory responses and ER stress. © 2016 BioFactors, 42(6):647-664, 2016.

  15. TRAIL-Induced Caspase Activation Is a Prerequisite for Activation of the Endoplasmic Reticulum Stress-Induced Signal Transduction Pathways.

    PubMed

    Lee, Dae-Hee; Sung, Ki Sa; Guo, Zong Sheng; Kwon, William Taehyung; Bartlett, David L; Oh, Sang Cheul; Kwon, Yong Tae; Lee, Yong J

    2016-05-01

    It is well known that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis can be initially triggered by surface death receptors (the extrinsic pathway) and subsequently amplified through mitochondrial dysfunction (the intrinsic pathway). However, little is known about signaling pathways activated by the TRAIL-induced endoplasmic reticulum (ER) stress response. In this study, we report that TRAIL-induced apoptosis is associated with the endoplasmic reticulum (ER) stress response. Human colorectal carcinoma HCT116 cells were treated with TRAIL and the ER stress-induced signal transduction pathway was investigated. During TRAIL treatment, expression of ER stress marker genes, in particular the BiP (binding immunoglobulin protein) gene, was increased and activation of the PERK (PKR-like ER kinase)-eIF2α (eukaryotic initiation factor 2α)-ATF4 (activating transcription factor 4)-CHOP (CCAAT-enhancer-binding protein homologous protein) apoptotic signal transduction pathway occurred. Experimental data from use of a siRNA (small interfering RNA) technique, caspase inhibitor, and caspase-3-deficient cell line revealed that TRAIL-induced caspase activation is a prerequisite for the TRAIL-induced ER stress response. TRAIL-induced ER stress was triggered by caspase-8-mediated cleavage of BAP31 (B cell receptor-associated protein 31). The involvement of the proapoptotic PERK-CHOP pathway in TRAIL-induced apoptosis was verified by using a PERK knockout (PERK(-/-)) mouse embryo fibroblast (MEF) cell line and a CHOP(-/-) MEF cell line. These results suggest that TRAIL-induced the activation of ER stress response plays a role in TRAIL-induced apoptotic death.

  16. Gel-Free/Label-Free Proteomic Analysis of Endoplasmic Reticulum Proteins in Soybean Root Tips under Flooding and Drought Stresses.

    PubMed

    Wang, Xin; Komatsu, Setsuko

    2016-07-01

    Soybean is a widely cultivated crop; however, it is sensitive to flooding and drought stresses. The adverse environmental cues cause the endoplasmic reticulum (ER) stress due to accumulation of unfolded or misfolded proteins. To investigate the mechanisms in response to flooding and drought stresses, ER proteomics was performed in soybean root tips. The enzyme activity of NADH cytochrome c reductase was two-fold higher in the ER than other fractions, indicating that the ER was isolated with high purity. Protein abundance of ribosomal proteins was decreased under both stresses compared to control condition; however, the percentage of increased ribosomes was two-fold higher in flooding compared to drought. The ER proteins related to protein glycosylation and signaling were in response to both stresses. Compared to control condition, calnexin was decreased under both stresses; however, protein disulfide isomerase-like proteins and heat shock proteins were markedly decreased under flooding and drought conditions, respectively. Furthermore, fewer glycoproteins and higher levels of cytosolic calcium were identified under both stresses compared to control condition. These results suggest that reduced accumulation of glycoproteins in response to both stresses might be due to dysfunction of protein folding through calnexin/calreticulin cycle. Additionally, the increased cytosolic calcium levels induced by flooding and drought stresses might disturb the ER environment for proper protein folding in soybean root tips.

  17. [Study on antagonistic effect of liangxue huayu recipe on endoplasmic reticulum stress-induced L02 hepatocyte apoptosis and its mechanism].

    PubMed

    Jiang, Ze-Qun; Yao, Zhi-Hua; Deng, Zheng-Ting; Jiang, Xin-Chao; Yan, Xiao-Jing; Chen, Wei-Ping

    2013-10-01

    Endoplasmic reticulum stress (ERS) is a new pathway inducing cell apoptosis that has been discovered in recent years. This study focused on the protective effect of Liangxue Huayu recipe (LHR) on tumor necrosis factor-alpha (TNF-alpha) and D-GalN-induced hepatocyte apoptosis. It found that TNF-alpha and D-GalN could obviously inhibit hepatocyte proliferation, induce cell apoptosis, and significantly increase free calcium ions in cytoplasms, as well as protein expressions of ERS apoptosis-related signal molecules phosphorylated PERK, phosphorylated elF2alpha, cleaved Caspase-12, GRP78 and CHOP. After the administration of LHR of different concentrations, compared with the TNF-alpha/GalN injury group, LHR could significantly alleviated L02 hepatocyte proliferation, decreased cell apoptosis, inhibited growth of intracytoplasmic free calcium content, and gradually reduced the protein expressions of phosphorylated PERK, phosphorylated elF2alpha, cleaved Caspase-12, GRP78 and CHOP. These findings indicated that LHR has the inhibitory effect on TNF-alpha and D-GalN-induced hepatocyte apoptosis. Its mechanism may be related to down-regulation of ERS apoptosis-related signal molecules phosphorylated PERK, phosphorylated elF2alpha, cleaved Caspase-12, GRP78 and CHOP that maintain calcium homeostasis in endoplasmic reticulum.

  18. Hypothyroidism minimizes the effects of acute hepatic failure caused by endoplasmic reticulum stress and redox environment alterations in rats.

    PubMed

    Blas-Valdivia, Vanessa; Cano-Europa, Edgar; Martinez-Perez, Yoalli; Lezama-Palacios, Ruth; Franco-Colin, Margarita; Ortiz-Butron, Rocio

    2015-10-01

    The aim of this study was to investigate if a protective effect from hypothyroidism in acute liver failure resulted from reduced endoplasmic reticulum stress and changes to the redox environment. Twenty male Sprague-Dawley rats were divided in four groups: (1) euthyroid (sham surgery), (2) hypothyroid, (3) euthyroid (sham surgery)+thioacetamide and (4) hypothyroid+thioacetamide. Hypothyroidism was confirmed two weeks after thyroidectomy, and thioacetamide (TAA) (400mg/kg, ip) was administrated to the appropriate groups for three days with supportive therapy. Grades of encephalopathy in all animals were determined using behavioral tests. Animals were decapitated and their blood was obtained to assess liver function. The liver was dissected: the left lobe was used for histology and the right lobe was frozen for biochemical assays. Body weight, rectal temperature and T4 concentration were lower in hypothyroid groups. When measurements of oxidative stress markers, redox environment, γ-glutamylcysteine synthetase and glutathione-S-transferase were determined, we observed that hypothyroid animals with TAA compensated better with oxidative damage than euthyroid animals treated with TAA. Furthermore, we measured reduced expressions of GADD34, caspase-12 and GRP78 and subsequently less hypothyroidism-induced cellular damage in hypothyroid animals. We conclude that hypothyroidism protects against hepatic damage caused by TAA because it reduces endoplasmic reticulum stress and changes to the redox environment.

  19. The Natural Pesticide Dihydrorotenone Induces Human Plasma Cell Apoptosis by Triggering Endoplasmic Reticulum Stress and Activating p38 Signaling Pathway

    PubMed Central

    Cao, Biyin; Zhang, Zubin; Li, Jie; Schimmer, Aaron D.; He, Sudan; Mao, Xinliang

    2013-01-01

    Dihydrorotenone (DHR) is a natural pesticide widely used in farming industry, such as organic produces. DHR is a potent mitochondrial inhibitor and probably induces Parkinsonian syndrome, however, it is not known whether DHR is toxic to other systems. In the present study, we evaluated the cytotoxicity of DHR on human plasma cells. As predicted, DHR impaired mitochondrial function by decreasing mitochondrial membrane potential in plasma cells. Because mito-dysfunction leads to unfolded protein response (UPR) and endoplasmic reticulum (ER) stress, we examined the signature proteins in ER stress, including GRP78, ATF4, and CHOP. After DHR treatment, these proteins were significantly upregulated. It is reported that activation of the mitogen-activated protein kinases p38 and JNK are involved in endoplasmic reticulum stress. However, in the subsequent study, DHR was found to activate p38 but not the JNK signaling. When pre-treated with p38 inhibitor SB203580, activation of p38 and cell apoptosis induced by DHR was partially blocked. Thus, we found that DHR induced human plasma cell death by activating the p38 but not the JNK signaling pathway. Because plasma cells are very important in the immune system, this study provided a new insight in the safety evaluation of DHR application. PMID:23922854

  20. Combined NADPH Oxidase 1 and Interleukin 10 Deficiency Induces Chronic Endoplasmic Reticulum Stress and Causes Ulcerative Colitis-Like Disease in Mice

    PubMed Central

    Tréton, Xavier; Pedruzzi, Eric; Guichard, Cécile; Ladeiro, Yannick; Sedghi, Shirin; Vallée, Mélissa; Fernandez, Neike; Bruyère, Emilie; Woerther, Paul-Louis; Ducroc, Robert; Montcuquet, Nicolas; Freund, Jean-Noel; Van Seuningen, Isabelle; Barreau, Frédérick; Marah, Assiya; Hugot, Jean-Pierre; Cazals-Hatem, Dominique; Bouhnik, Yoram; Daniel, Fanny; Ogier-Denis, Eric

    2014-01-01

    Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting the rectum which progressively extents. Its etiology remains unknown and the number of treatments available is limited. Studies of UC patients have identified an unbalanced endoplasmic reticulum (ER) stress in the non-inflamed colonic mucosa. Animal models with impaired ER stress are sensitive to intestinal inflammation, suggesting that an unbalanced ER stress could cause inflammation. However, there are no ER stress-regulating strategies proposed in the management of UC partly because of the lack of relevant preclinical model mimicking the disease. Here we generated the IL10/Nox1dKO mouse model which combines immune dysfunction (IL-10 deficiency) and abnormal epithelium (NADPH oxidase 1 (Nox1) deficiency) and spontaneously develops a UC-like phenotype with similar complications (colorectal cancer) than UC. Our data identified an unanticipated combined role of IL10 and Nox1 in the fine-tuning of ER stress responses in goblet cells. As in humans, the ER stress was unbalanced in mice with decreased eIF2α phosphorylation preceding inflammation. In IL10/Nox1dKO mice, salubrinal preserved eIF2α phosphorylation through inhibition of the regulatory subunit of the protein phosphatase 1 PP1R15A/GADD34 and prevented colitis. Thus, this new experimental model highlighted the central role of epithelial ER stress abnormalities in the development of colitis and defined the defective eIF2α pathway as a key pathophysiological target for UC. Therefore, specific regulators able to restore the defective eIF2α pathway could lead to the molecular remission needed to treat UC. PMID:25014110

  1. Combined NADPH oxidase 1 and interleukin 10 deficiency induces chronic endoplasmic reticulum stress and causes ulcerative colitis-like disease in mice.

    PubMed

    Tréton, Xavier; Pedruzzi, Eric; Guichard, Cécile; Ladeiro, Yannick; Sedghi, Shirin; Vallée, Mélissa; Fernandez, Neike; Bruyère, Emilie; Woerther, Paul-Louis; Ducroc, Robert; Montcuquet, Nicolas; Freund, Jean-Noel; Van Seuningen, Isabelle; Barreau, Frédérick; Marah, Assiya; Hugot, Jean-Pierre; Cazals-Hatem, Dominique; Bouhnik, Yoram; Daniel, Fanny; Ogier-Denis, Eric

    2014-01-01

    Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting the rectum which progressively extents. Its etiology remains unknown and the number of treatments available is limited. Studies of UC patients have identified an unbalanced endoplasmic reticulum (ER) stress in the non-inflamed colonic mucosa. Animal models with impaired ER stress are sensitive to intestinal inflammation, suggesting that an unbalanced ER stress could cause inflammation. However, there are no ER stress-regulating strategies proposed in the management of UC partly because of the lack of relevant preclinical model mimicking the disease. Here we generated the IL10/Nox1dKO mouse model which combines immune dysfunction (IL-10 deficiency) and abnormal epithelium (NADPH oxidase 1 (Nox1) deficiency) and spontaneously develops a UC-like phenotype with similar complications (colorectal cancer) than UC. Our data identified an unanticipated combined role of IL10 and Nox1 in the fine-tuning of ER stress responses in goblet cells. As in humans, the ER stress was unbalanced in mice with decreased eIF2α phosphorylation preceding inflammation. In IL10/Nox1dKO mice, salubrinal preserved eIF2α phosphorylation through inhibition of the regulatory subunit of the protein phosphatase 1 PP1R15A/GADD34 and prevented colitis. Thus, this new experimental model highlighted the central role of epithelial ER stress abnormalities in the development of colitis and defined the defective eIF2α pathway as a key pathophysiological target for UC. Therefore, specific regulators able to restore the defective eIF2α pathway could lead to the molecular remission needed to treat UC.

  2. Regulation of σ-1 Receptors and Endoplasmic Reticulum Chaperones in the Brain of Methamphetamine Self-Administering Rats

    PubMed Central

    Hayashi, Teruo; Justinova, Zuzana; Hayashi, Eri; Cormaci, Gianfrancesco; Mori, Tomohisa; Tsai, Shang-Yi; Barnes, Chanel; Goldberg, Steven R.

    2010-01-01

    σ-1 Receptors are endoplasmic reticulum (ER) chaperones that are implicated in the neuroplasticity associated with psychostimulant abuse. We immunocytochemically examined the distribution of σ-1 receptors in the brain of drug-naive rats and then examined the dynamics of σ-1 receptors and other ER chaperones in specific brain subregions of rats that self-administered methamphetamine, received methamphetamine passively, or received only saline injections. σ-1 Receptors were found to be expressed in moderate to high levels in the olfactory bulb, striatum, nucleus accumbens shell, olfactory tubercle, amygdala, hippocampus, red nucleus, ventral tegmental area, substantia nigra, and locus ceruleus. Methamphetamine, whether self-administered or passively received, significantly elevated ER chaperones including the σ-1 receptor, BiP, and calreticulin in the ventral tegmental area and substantia nigra. In the olfactory bulb, however, only the σ-1 receptor chaperone was increased, and this increase occurred only in rats that actively self-administered methamphetamine. Consistent with an increase in σ-1 receptors, extracellular signal-regulated kinase was found to be activated and protein kinase A attenuated in the olfactory bulb of methamphetamine self-administering rats. σ-1 Receptors in the olfactory bulb were found to be colocalized with dopamine D1 receptors. These results indicate that methamphetamine induces ER stress in the ventral tegmental area and substantia nigra in rats whether the drug is received actively or passively. However, the changes seen only in rats that actively self-administered methamphetamine suggest that D1 and σ-1 receptors in the olfactory bulb might play an important role in the motivational conditioning/learning aspects of methamphetamine self-administration in the rat. PMID:19940104

  3. Reconstitution and regulation of cation-selective channels from cardiac sarcoplasmic reticulum.

    PubMed

    Rousseau, E; Chabot, H; Beaudry, C; Muller, B

    1992-09-08

    In order to study the conductances of the Sarcoplasmic Reticulum (SR) membrane, microsomal fractions from cardiac SR were isolated by differential and sucrose gradient centrifugations and fused into planar lipid bilayers (PLB) made of phospholipids. Using either KCl or K-gluconate solutions, a large conducting K+ selective channel was characterized by its ohmic conductance (152 pS in 150 mM K+), and the presence of short and long lasting subconducting states. Its open probability Po increased with depolarizing voltages, thus supporting the idea that this channel might allow counter-charge movements of monovalent cations during rapid SR Ca2+ release. An heterogeneity in the kinetic behavior of this channel would suggest that the cardiac SR K+ channels might be regulated by cytoplasmic, luminal, or intra SR membrane biochemical mechanisms. Since the behavior was not modified by variations of [Ca2+] nor by the addition of soluble metabolites such as ATP, GTP, cAMP, cGMP, nor by phosphorylation conditions on both sides of the PLB, a specific interaction with a SR membrane component is postulated. Another cation selective channel was studied in asymmetric Ca2+, Ba2+ or Mg(2+)-HEPES buffers. This channel displayed large conductance values for the above divalent cations 90, 100, and 40 pS, respectively. This channel was activated by microM Ca2+ while its Ca2+ sensitivity was potentiated by millimolar ATP. However Mg2+ and calmodulin modulated its gating behavior. Ca2+ releasing drugs such as caffeine and ryanodine increased its Po. All these features are characteristics of the SR Ca2+ release channel. The ryanodine receptor which has been purified and reconstituted into PLB, may form a cation selective pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Cu, Zn Superoxide Dismutase and NADP(H) Homeostasis Are Required for Tolerance of Endoplasmic Reticulum Stress in Saccharomyces cerevisiae

    PubMed Central

    Tan, Shi-Xiong; Teo, Mariati; Lam, Yuen T.; Perrone, Gabriel G.

    2009-01-01

    Genome-wide screening for sensitivity to chronic endoplasmic reticulum (ER) stress induced by dithiothreitol and tunicamycin (TM) identified mutants deleted for Cu, Zn superoxide dismutase (SOD) function (SOD1, CCS1) or affected in NADPH generation via the pentose phosphate pathway (TKL1, RPE1). TM-induced ER stress led to an increase in cellular superoxide accumulation and an increase in SOD1 expression and Sod1p activity. Prior adaptation of the hac1 mutant deficient in the unfolded protein response (UPR) to the superoxide-generating agent paraquat reduced cell death under ER stress. Overexpression of the ER oxidoreductase Ero1p known to generate hydrogen peroxide in vitro, did not lead to increased superoxide levels in cells subjected to ER stress. The mutants lacking SOD1, TKL1, or RPE1 exhibited decreased UPR induction under ER stress. Sensitivity of the sod1 mutant to ER stress and decreased UPR induction was partially rescued by overexpression of TKL1 encoding transketolase. These data indicate an important role for SOD and cellular NADP(H) in cell survival during ER stress, and it is proposed that accumulation of superoxide affects NADP(H) homeostasis, leading to reduced UPR induction during ER stress. PMID:19129474

  5. Protective effect of paraoxonase-2 against endoplasmic reticulum stress-induced apoptosis is lost upon disturbance of calcium homoeostasis.

    PubMed

    Horke, Sven; Witte, Ines; Wilgenbus, Petra; Altenhöfer, Sebastian; Krüger, Maximilian; Li, Huige; Förstermann, Ulrich

    2008-12-15

    PON2 (paraoxonase-2) is a ubiquitously expressed antioxidative protein which is largely found in the ER (endoplasmic reticulum). Addressing the cytoprotective functions of PON2, we observed that PON2 overexpression provided significant resistance to ER-stress-induced caspase 3 activation when the ER stress was induced by interference with protein modification (by tunicamycin or dithiothreitol), but not when ER stress was induced by disturbance of Ca(2+) homoeostasis (by thapsigargin or A23187). When analysing the underlying molecular events, we found an activation of the PON2 promoter in response to all tested ER-stress-inducing stimuli. However, only tunicamycin and dithiothreitol resulted in increased PON2 mRNA and protein levels. In contrast, when ER stress was caused by thapsigargin or A23187, we observed a Ca(2+)-dependent active degradation of PON2 mRNA, elicited by its 5'-untranslated region. In addition, thapsigargin and A23187 also induced PON2 protein degradation by a Ca(2+)-dependent calpain-mediated mechanism. Thus we provide evidence that independent mechanisms mediate the degradation of PON2 mRNA and protein after disturbance of Ca(2+) homoeostasis. Furthermore, because Ca(2+)-disturbance induces ER stress, but abrogates the otherwise protective function of PON2 against ER-stress-induced apoptosis, we propose that the underlying cause of ER stress determines the efficacy of putative cellular defence mechanisms.

  6. Involvement of Endoplasmic Reticulum Stress, Autophagy, and Apoptosis in Advanced Glycation End Products-Induced Glomerular Mesangial Cell Injury

    PubMed Central

    Chiang, Chih-Kang; Wang, Ching-Chia; Lu, Tien-Fong; Huang, Kuo-How; Sheu, Meei-Ling; Liu, Shing-Hwa; Hung, Kuan-Yu

    2016-01-01

    Advanced glycation end-products (AGEs)-induced mesangial cell death is one of major causes of glomerulus dysfunction in diabetic nephropathy. Both endoplasmic reticulum (ER) stress and autophagy are adaptive responses in cells under environmental stress and participate in the renal diseases. The role of ER stress and autophagy in AGEs-induced mesangial cell death is still unclear. Here, we investigated the effect and mechanism of AGEs on glomerular mesangial cells. AGEs dose-dependently decreased mesangial cell viability and induced cell apoptosis. AGEs also induced ER stress signals in a time- and dose-dependent manner. Inhibition of ER stress with 4-phenylbutyric acid effectively inhibited the activation of eIF2α and CHOP signals and reversed AGEs-induced cell apoptosis. AGEs also activated LC-3 cleavage, increased Atg5 expression, and decreased p62 expression, which indicated the autophagy induction in mesangial cells. Inhibition of autophagy by Atg5 siRNAs transfection aggravated AGEs-induced mesangial cell apoptosis. Moreover, ER stress inhibition by 4-phenylbutyric acid significantly reversed AGEs-induced autophagy, but autophagy inhibition did not influence the AGEs-induced ER stress-related signals activation. These results suggest that AGEs induce mesangial cell apoptosis via an ER stress-triggered signaling pathway. Atg5-dependent autophagy plays a protective role. These findings may offer a new strategy against AGEs toxicity in the kidney. PMID:27665710

  7. DBP-induced endoplasmic reticulum stress in male germ cells causes autophagy, which has a cytoprotective role against apoptosis in vitro and in vivo.

    PubMed

    Zhang, Guowei; Liu, Kaijun; Ling, Xi; Wang, Zhi; Zou, Peng; Wang, Xiaogang; Gao, Jianfang; Yin, Li; Zhang, Xi; Liu, Jinyi; Ao, Lin; Cao, Jia

    2016-03-14

    Recently, spermatogenic cell apoptosis was shown to play a key role in the induction of testicular atrophy by dibutyl phthalate (DBP), thus causing reproductive toxicology. However, the molecular events induced by DBP in apoptotic germ cells remain unclear. In the present study, the mouse spermatocyte-derived GC-2 cell line was exposed to different doses of DBP. We found that DBP induced marked apoptosis in GC-2 cells. The levels of the major endoplasmic reticulum (ER) stress markers GRP-78, ATF-6, and p-EIF2α were elevated when GC-2 cells were exposed to 25 μM DBP and increased in a dose-dependent manner at higher concentrations. Furthermore, at a concentration that resulted in significant apoptosis (100 μM), CHOP, which plays a convergent role in ER stress-mediated apoptosis and is regulated by various upstream ER stress signals, was activated and partially contributed to the DBP-induced apoptosis. However, inhibition of ER stress by 4-PBA, a chemical with chaperone-like activities, augmented the GC-2 cell apoptosis induced by DBP. Further experiments demonstrated that DBP-induced ER stress additionally had a protective role, mediated through the activation of autophagy. These results were confirmed in prepubertal rat testis germ cells; DBP treatment significantly induced testicular atrophy, accompanied by apoptosis, ER stress, and autophagy. Inhibition of ER stress and autophagy significantly aggravated the DBP-induced damage to the germ cells and testes. Taken together, our data suggest that DBP-induced ER stress in germ cells has a cytoprotective effect that is mediated through autophagy activation. These findings provide novel clues regarding the molecular events involved in DBP-induced germ cell apoptosis.

  8. Cyclin-dependent kinase 5 contributes to endoplasmic reticulum stress induced podocyte apoptosis via promoting MEKK1 phosphorylation at Ser280 in diabetic nephropathy.

    PubMed

    Zhang, Yue; Gao, Xiang; Chen, Shuanggang; Zhao, Min; Chen, Jing; Liu, Rui; Cheng, Shengyang; Qi, Mengyuan; Wang, Shuo; Liu, Wei

    2017-02-01

    Endoplasmic reticulum (ER) stress has been reported to be associated with podocyte apoptosis in diabetic nephropathy, but the mechanism of ER signaling in podocyte apoptosis hasn't been fully understood. Our previous studies have demonstrated that Cyclin-dependent kinase 5 (Cdk5) was associated with podocyte apoptosis in diabetic nephropathy. The present study was designed to examine whether and how Cdk5 activity plays a role in ER stress induced podocyte apoptosis in diabetic nephropathy. The results showed that along with induction of Cdk5 and apoptosis, GRP78 and its two sensors as well as CHOP and cleaved caspase-12 were induced in high glucose treated podocytes. These responses were attenuated by treated salubrinal. The ER stress inducer, tunicamycin, also up-regulated the kinase activity and protein expression of Cdk5 in podocytes accompanied with the increasing of GRP78. On the other hand, Cdk5 phosphorylates MEKK1 at Ser280 in tunicamycin treated podocytes, and together, they increase the JNK phosphorylation. Moreover, disruption of this pathway can decrease the podocyte apoptosis induced by tunicamycin. Therefore, our study proved that Cdk5 may play an important role in ER stress induced podocyte apoptosis through MEKK1/JNK pathway in diabetic nephropathy.

  9. ACSL3 and GSK-3β are essential for lipid upregulation induced by endoplasmic reticulum stress in liver cells.

    PubMed

    Chang, Yung-Sheng; Tsai, Chien-Ting; Huangfu, Chien-An; Huang, Wen-Ya; Lei, Huan-Yao; Lin, Chiou-Feng; Su, Ih-Jen; Chang, Wen-Tsan; Wu, Pei-Huan; Chen, Ya-Ting; Hung, Jui-Hsiang; Young, Kung-Chia; Lai, Ming-Derg

    2011-03-01

    The endoplasmic reticulum (ER) is essential for lipid biosynthesis, and stress signals in this organelle are thought to alter lipid metabolism. Elucidating the mechanisms that underlie the dysregulation of lipid metabolism in hepatocytes may lead to novel therapeutic approaches for the treatment of lipid accumulation. We first tested the effects of several inhibitors on lipid dysregulation induced by tunicamycin, an ER stress inducer. Triacsin C, an inhibitor of long-chain acyl-CoA synthetase (ACSL) 1, 3, and 4, was the most potent among these inhibitors. We then analyzed the expression of the ACSL family during ER stress. The expression of ACSL3 was induced by ER stress in HuH-7 cells and in mice livers. ACSL3 shRNA, but not ACSL1 shRNA, inhibited the induction of lipid accumulation. GSK-3β inhibitors attenuated ACSL3 expression and the lipid accumulation induced by ER stress in HuH-7 cells. shRNA that target GSK-3β also inhibited the upregulation of ACSL3 and lipid accumulation in HuH-7 and HepG2 cells. The hepatitis B virus mutant large surface protein, which is known to induce ER stress, increased the lipid content of cells. Similarly, Triacsin C, and GSK-3β inhibitors abrogated the lipid dysregulation caused by the hepatitis B virus mutant large surface protein. Altogether, ACSL3 and GSK-3β represent novel therapeutic targets for lipid dysregulation by ER stress.

  10. Toll-like receptor 4-induced endoplasmic reticulum stress contributes to impairment of vasodilator action of insulin

    PubMed Central

    Jang, Hyun-Ju; Hwang, Daniel H.

    2015-01-01

    Impairment of vasodilator action of insulin is associated with endothelial dysfunction and insulin resistance. Activation of Toll-like receptor 4 (TLR4) induces proinflammatory response and endoplasmic reticulum (ER) stress. Saturated fatty acids (SFA) activate TLR4, which induces ER stress and endothelial dysfunction. Therefore, we determined whether TLR4-mediated ER stress is an obligatory step mediating SFA-induced endothelial dysfunction. Palmitate stimulated proinflammatory responses and ER stress, and this was suppressed by knockdown of TLR4 in primary human aortic endothelial cells (HAEC). Next, we examined the role of TLR4 in vasodilatory responses in intact vessels isolated from wild-type (WT, C57BL/6) and TLR4-KO mice after feeding high-fat (HFD) or normal chow diet (NCD) for 12 wk. Arterioles isolated from HFD WT mice exhibited impaired insulin-stimulated vasodilation compared with arterioles isolated from NCD WT mice. Deficiency of TLR4 was protective from HFD-induced impairment of insulin-stimulated vasodilation. There were no differences in acetylcholine (Ach)- or sodium nitroprusside (SNP)-stimulated vasodilation between the two groups. Furthermore, we examined whether ER stress is involved in SFA-induced impairment of vasodilator actions of insulin. Infusion of palmitate showed the impairment of vasodilatory response to insulin, which was ameliorated by coinfusion with tauroursodeoxycholic acid (TUDCA), an ER stress suppressor. Taken together, the results suggest that TLR4-induced ER stress may be an obligatory step mediating the SFA-mediated endothelial dysfunction. PMID:26522062

  11. Endoplasmic reticulum stress is involved in the lidocaine-induced apoptosis in SH-SY5Y neuroblastoma cells.

    PubMed

    Li, Kehan; Han, Xuechang

    2015-05-01

    Lidocaine has been indicated to promote apoptosis and to promote endoplasmic reticulum (ER) stress. However, the mechanism underlining ER stress-mediated apoptosis is unclear. In the present study, we investigated the promotion to ER stress in the lidocaine-induced apoptosis in human neuroblastoma SH-SY5Y cells. Firstly, we confirmed that lidocaine treatment induced apoptosis in SH-SY5Y cells, time-dependently and dose-dependently, via MTT cell viability assay and annexin V/FITC apoptosis detection with a FACScan flow cytometer. And the anti-apoptosis Bcl-2 and Bcl-xL were downregulated, whereas the apoptosis-executive caspase 3 was promoted through Western blot assay and caspase 3 activity assay. Moreover, the ER stress-associated binding immunoglobulin protein (BiP), PKR-like ER kinase (PERK), activating transcription factor 4 (ATF4) and CCAAT/enhancer-binding protein homologous protein (CHOP) were also upregulated at both mRNA and protein levels by lidocaine treatment. On the other hand, downregulation of the ER stress-associated BiP by RNAi method not only blocked the lidocaine-promoted ER stress but also attenuated the lidocaine-induced SH-SY5Y cell apoptosis. In conclusion, the present study confirmed the involvement of ER stress in the lidocaine-induced apoptosis in human neuroblastoma SH-SY5Y cells. Our study provides a better understanding on the mechanism of lidocaine's neurovirulence.

  12. The Aspergillus fumigatus metacaspases CasA and CasB facilitate growth under conditions of endoplasmic reticulum stress.

    PubMed

    Richie, Daryl L; Miley, Michael D; Bhabhra, Ruchi; Robson, Geoffrey D; Rhodes, Judith C; Askew, David S

    2007-01-01

    We have examined the contribution of metacaspases to the growth and stress response of the opportunistic human mould pathogen, Aspergillus fumigatus, based on increasing evidence implicating the yeast metacaspase Yca1p in apoptotic-like programmed cell death. Single metacaspase-deficient mutants were constructed by targeted disruption of each of the two metacaspase genes in A. fumigatus, casA and casB, and a metacaspase-deficient mutant, DeltacasA/DeltacasB, was constructed by disrupting both genes. Stationary phase cultures of wild-type A. fumigatus were associated with the appearance of typical markers of apoptosis, including elevated proteolytic activity against caspase substrates, phosphatidylserine exposure on the outer leaflet of the membrane, and loss of viability. By contrast, phosphatidylserine exposure was not observed in stationary phase cultures of the DeltacasA/DeltacasB mutant, although caspase activity and viability was indistinguishable from wild type. The mutant retained wild-type virulence and showed no difference in sensitivity to a range of pro-apoptotic stimuli that have been reported to initiate yeast apoptosis. However, the DeltacasA/DeltacasB mutant showed a growth detriment in the presence of agents that disrupt endoplasmic reticulum homeostasis. These findings demonstrate that metacaspase activity in A. fumigatus contributes to the apoptotic-like loss of membrane phospholipid asymmetry at stationary phase, and suggest that CasA and CasB have functions that support growth under conditions of endoplasmic reticulum stress.

  13. Glucose Amplifies Fatty Acid-Induced Endoplasmic Reticulum Stress in Pancreatic β-Cells via Activation of mTORC1

    PubMed Central

    Bachar, Etti; Ariav, Yafa; Ketzinel-Gilad, Mali; Cerasi, Erol; Kaiser, Nurit; Leibowitz, Gil

    2009-01-01

    Background Palmitate is a potent inducer of endoplasmic reticulum (ER) stress in β-cells. In type 2 diabetes, glucose amplifies fatty-acid toxicity for pancreatic β-cells, leading to β-cell dysfunction and death. Why glucose exacerbates β-cell lipotoxicity is largely unknown. Glucose stimulates mTORC1, an important nutrient sensor involved in the regulation of cellular stress. Our study tested the hypothesis that glucose augments lipotoxicity by stimulating mTORC1 leading to increased β-cell ER stress. Principal Findings We found that glucose amplifies palmitate-induced ER stress by increasing IRE1α protein levels and activating the JNK pathway, leading to increased β-cell apoptosis. Moreover, glucose increased mTORC1 activity and its inhibition by rapamycin decreased β-cell apoptosis under conditions of glucolipotoxicity. Inhibition of mTORC1 by rapamycin did not affect proinsulin and total protein synthesis in β-cells incubated at high glucose with palmitate. However, it decreased IRE1α expression and signaling and inhibited JNK pathway activation. In TSC2-deficient mouse embryonic fibroblasts, in which mTORC1 is constitutively active, mTORC1 regulated the stimulation of JNK by ER stressors, but not in response to anisomycin, which activates JNK independent of ER stress. Finally, we found that JNK inhibition decreased β-cell apoptosis under conditions of glucolipotoxicity. Conclusions/Significance Collectively, our findings suggest that mTORC1 mediates glucose amplification of lipotoxicity, acting through activation of ER stress and JNK. Thus, mTORC1 is an important transducer of ER stress in β-cell glucolipotoxicity. Moreover, in stressed β-cells mTORC1 inhibition decreases IRE1α protein expression and JNK activity without affecting ER protein load, suggesting that mTORC1 regulates the β-cell stress response to glucose and fatty acids by modulating the synthesis and activity of specific proteins involved in the execution of the ER stress response

  14. Inhibition of Brain Mitogen-Activated Protein Kinase Signaling Reduces Central Endoplasmic Reticulum Stress and Inflammation and Sympathetic Nerve Activity in Heart Failure Rats.

    PubMed

    Wei, Shun-Guang; Yu, Yang; Weiss, Robert M; Felder, Robert B

    2016-01-01

    Mitogen-activated protein kinase (MAPK) signaling and endoplasmic reticulum (ER) stress in the brain have been implicated in the pathophysiology of hypertension. This study determined whether ER stress occurs in subfornical organ and hypothalamic paraventricular nucleus in heart failure (HF) and how MAPK signaling interacts with ER stress and other inflammatory mediators. HF rats had significantly higher levels of the ER stress biomarkers (glucose-regulated protein 78, activating transcription factor 6, activating transcription factor 4, X-box binding protein 1, P58(IPK), and C/EBP homologous protein) in subfornical organ and paraventricular nucleus, which were attenuated by a 4-week intracerebroventricular infusion of inhibitors selective for p44/42 MAPK (PD98059), p38 MAPK (SB203580), or c-Jun N-terminal kinase (SP600125). HF rats also had higher mRNA levels of tumor necrosis factor-α, interleukin-1β, cyclooxygenase-2, and nuclear factor-κB p65, and a lower mRNA level of IκB-α, in subfornical organ and paraventricular nucleus, compared with SHAM rats, and these indicators of increased inflammation were attenuated in the HF rats treated with the MAPK inhibitors. Plasma norepinephrine level was higher in HF rats than in SHAM rats but was reduced in the HF rats treated with PD98059 and SB203580. A 4-week intracerebroventricular infusion of PD98059 also improved some hemodynamic and anatomic indicators of left ventricular function in HF rats. These data demonstrate that ER stress increases in the subfornical organ and paraventricular nucleus of rats with ischemia-induced HF and that inhibition of brain MAPK signaling reduces brain ER stress and inflammation and decreases sympathetic excitation in HF. An interaction between MAPK signaling and ER stress in cardiovascular regions of the brain may contribute to the development of HF.

  15. The dysregulation of endoplasmic reticulum stress response in acute-on-chronic liver failure patients caused by acute exacerbation of chronic hepatitis B.

    PubMed

    Ren, F; Shi, H; Zhang, L; Zhang, X; Wen, T; Xie, B; Zheng, S; Chen, Y; Li, L; Chen, D; Duan, Z

    2016-01-01

    Although endoplasmic reticulum (ER) stress is critical in various liver diseases, its role in acute-on-chronic liver failure (AoCLF) caused by acute exacerbation of chronic hepatitis B (CHB) is still elusive. This study aimed to analyse ER stress responses in the progression of HBV-related AoCLF. Normal liver tissues (n = 10), liver tissues of CHB (n = 12) and HBV-related patients with AoCLF (n = 19) were used. Electron microscopy of the ultrastructure of the ER was carried out on liver specimens. The gene and protein expression levels of ER stress-related genes were measured. We further analysed the correlation between the expression levels of ER stress-related molecules and liver injury. Electron microscopy identified typical features of the ER microstructure in AoCLF subjects. Among the three pathways of unfolded protein responses, the PKR-like ER kinase and inositol-requiring enzyme 1 signalling pathway were activated in CHB subjects and inactivated in AoCLF subjects, while the activating transcription factor 6 signalling pathway was sustained in the activated form during the progression of AoCLF; the expression of glucose-regulated protein (Grp)78 and Grp94 was gradually decreased in AoCLF subjects compared to healthy individuals and CHB subjects, showing a negative correlation with serum ALT, AST and TBIL; moreover, the ER stress-related apoptosis molecules were activated in the progression of acute exacerbation of CHB. The dysregulated ER stress response may play a complicated role in the pathogenesis of AoCLF, and a severe ER stress response may predict the occurrence of AoCLF caused by acute exacerbation of CHB.

  16. Endoplasmic reticulum stress induces myostatin precursor protein and NF-kappaB in cultured human muscle fibers: relevance to inclusion body myositis.

    PubMed

    Nogalska, Anna; Wojcik, Slawomir; Engel, W King; McFerrin, Janis; Askanas, Valerie

    2007-04-01

    Sporadic-inclusion body myositis (s-IBM) is the most common progressive muscle disease of older persons. It leads to pronounced muscle fiber atrophy and weakness, and there is no successful treatment. We have previously shown that myostatin precursor protein (MstnPP) and myostatin (Mstn) dimer are increased in biopsied s-IBM muscle fibers, and proposed that MstnPP/Mstn increase may contribute to muscle fiber atrophy and weakness in s-IBM patients. Mstn is known to be a negative regulator of muscle fiber mass. It is synthesized as MstnPP, which undergoes posttranslational processing in the muscle fiber to produce mature, active Mstn. To explore possible mechanisms involved in Mstn abnormalities in s-IBM, in the present study we utilized primary cultures of normal human muscle fibers and experimentally modified the intracellular micro-environment to induce endoplasmic-reticulum (ER)-stress, thereby mimicking an important aspect of the s-IBM muscle fiber milieu. ER stress was induced by treating well-differentiated cultured muscle fibers with either tunicamycin or thapsigargin, both well-established ER stress inducers. Our results indicate for the first time that the ER stress significantly increased MstnPP mRNA and protein. The results also suggest that in our system ER stress activates NF-kappaB, and we suggest that MstnPP increase occurred through the ER-stress-activated NF-kappaB. We therefore propose a novel mechanism leading to the Mstn increase in s-IBM. Accordingly, interfering with pathways inducing ER stress, NF-kappaB activation or its action on the MstnPP gene promoter might prevent Mstn increase and provide a new therapeutic approach for s-IBM and, possibly, for muscle atrophy in other neuromuscular diseases.

  17. Shengmai Injection Improved Doxorubicin-Induced Cardiomyopathy by Alleviating Myocardial Endoplasmic Reticulum Stress and Caspase-12 Dependent Apoptosis

    PubMed Central

    Chen, Yu; Tang, Yong; Xiang, Yin; Xie, Yu-Quan; Huang, Xiao-Hong; Zhang, Ya-Chen

    2015-01-01

    Background. Apoptosis plays vital roles in the progression of doxorubicin-induced cardiomyopathy (DOX-CM). Endoplasmic reticulum stress (ER stress) could induce specific apoptosis by caspase-12 dependent pathway. Shengmai Injection (SMI), a famous Traditional Chinese Medicine, could alleviate the heart damage via inhibiting myocardial apoptosis. However, it is unknown whether SMI can alleviate ER stress and its specific apoptosis in the setting of DOX-CM. Objective. To explore the effects of SMI on heart function, myocardial ER stress, and apoptosis of DOX-CM rats. Methods. Rats with DOX-CM were treated by SMI. Heart function was assessed by echocardiograp