scholarly journals The reductase NCB5OR is responsive to the redox status in β-cells and is not involved in the ER stress response

2007 ◽  
Vol 404 (3) ◽  
pp. 467-476 ◽  
Author(s):  
Kevin Larade ◽  
Zhi-gang Jiang ◽  
Andre Dejam ◽  
Hao Zhu ◽  
H. Franklin Bunn
Keyword(s):  
Antioxidant Enzymes ◽  
Stress Response ◽  
Er Stress ◽  
Microarray Analysis ◽  
Promoter Activity ◽  
Binding Protein ◽  
Redox Status ◽  
Mrna Levels ◽  
Β Cells ◽  
Er Stress Response

The novel reductase NCB5OR (NADPH cytochrome b5 oxidoreductase) resides in the ER (endoplasmic reticulum) and may protect cells against ER stress. Levels of BiP (immunoglobulin heavy-chain-binding protein), CHOP (CCAAT/enhancer-binding protein homologous protein) and XBP-1 (X-box-binding protein-1) did not differ in WT (wild-type) and KO (Ncb5or-null) tissues or MEFs (mouse embryonic fibroblasts), and XBP-1 remained unspliced. MEFs treated with inducers of ER stress demonstrated no change in Ncb5or expression and expression of ER-stress-induced genes was not enhanced. Induction of ER stress in β-cell lines did not change Ncb5or expression or promoter activity. Transfection with Ncb5or-specific siRNA (small interfering RNA) yielded similar results. Microarray analysis of mRNA from islets and liver of WT and KO animals revealed no significant changes in ER-stress-response genes. Induction of oxidative stress in βTC3 cells did not alter Ncb5or mRNA levels or promoter activity. However, KO islets were more sensitive to streptozotocin when compared with WT islets. MEFs incubated with nitric oxide donors showed no difference in cell viability or levels of nitrite produced. No significant differences in mRNA expression of antioxidant enzymes were observed when comparing WT and KO tissues; however, microarray analysis of islets indicated slightly enhanced expression of some antioxidant enzymes in the KO islets. Short-term tBHQ (t-butylhydroquinone) treatment increased Ncb5or promoter activity, although longer incubation times yielded a dose-dependent decrease in activity. This response appears to be due to a consensus ARE (antioxidant-response element) present in the Ncb5or promoter. In summary, NCB5OR does not appear to be involved in ER stress, although it may be involved in maintaining or regulating the redox status in β-cells.

scholarly journals Reducing endoplasmic reticulum stress does not improve steatohepatitis in mice fed a methionine- and choline-deficient diet

2012 ◽  
Vol 303 (1) ◽  
pp. G54-G59 ◽  
Author(s):  
Anne S. Henkel ◽  
Amanda M. Dewey ◽  
Kristy A. Anderson ◽  
Shantel Olivares ◽  
Richard M. Green
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Er Stress ◽  
Hepatic Steatosis ◽  
Binding Protein ◽  
Mrna Levels ◽  
Primary Role ◽  
Chemical Chaperones ◽  
Er Stress Response ◽  
Markers Of Inflammation

Endoplasmic reticulum (ER) stress has been implicated in the pathogenesis of nonalcoholic steatohepatitis. The ER stress response is activated in the livers of mice fed a methionine- and choline-deficient (MCD) diet, yet the role of ER stress in the pathogenesis of MCD diet-induced steatohepatitis is unknown. Using chemical chaperones on hepatic steatosis and markers of inflammation and fibrosis in mice fed a MCD diet, we aim to determine the effects of reducing ER stress. C57BL/6J mice were fed a MCD diet with or without the ER chemical chaperones 4-phenylbutyric acid (PBA) and tauroursodeoxycholic acid (TUDCA) for 2 wk. TUDCA and PBA effectively attenuated the ER stress response in MCD diet-fed mice, as evidenced by reduced protein levels of phosphorylated eukaryotic initiation factor 2α and phosphorylated JNK and suppression of mRNA levels of CCAAT/enhancer binding protein homologous protein, glucose-regulated protein 78 kDa, and X-box binding protein 1. However, PBA and TUDCA did not decrease MCD diet-induced hepatic steatosis. MCD diet-induced hepatic inflammation, as evidenced by increased plasma alanine aminotransferase and induction of hepatic TNFα expression, was also not reduced by PBA or TUDCA. PBA and TUDCA did not attenuate MCD diet-induced upregulation of the fibrosis-associated genes tissue inhibitor of metalloproteinase-1 and matrix metalloproteinase-9. ER chemical chaperones reduce MCD diet-induced ER stress, yet they do not improve MCD diet-induced hepatic steatosis, inflammation, or activation of genes associated with fibrosis. These data suggest that although the ER stress response is activated by the MCD diet, it does not have a primary role in the pathogenesis of MCD diet-induced steatohepatitis.

scholarly journals Transcriptional regulation of mouse mesencephalic astrocyte-derived neurotrophic factor in Neuro2a cells

2013 ◽  
Vol 18 (3) ◽  
Author(s):  
Kentaro Oh-Hashi ◽  
Yoko Hirata ◽  
Kazutoshi Kiuchi
Keyword(s):  
Transcription Factors ◽  
Stress Response ◽  
Er Stress ◽  
Neurotrophic Factor ◽  
Promoter Activity ◽  
Luciferase Reporter ◽  
Mrna Levels ◽  
Er Stress Response ◽  
Neuro2a Cells ◽  
Flanking Region

AbstractMesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel type of trophic factor. Recent studies indicate that the MANF gene is induced in response to endoplasmic reticulum (ER) stress through ER stress response element II (ERSE-II) in its 5′-flanking region. In this study, we evaluated the roles of six ER stress response transcription factors in the regulation of the promoter activities of the mouse MANF gene via ERSE-II using various types of mutant MANF luciferase reporter constructs. Treatment with thapsigargin (Tg) induced MANF mRNA generation in parallel with the elevation of ATF6α, sXBP and Luman mRNA levels in Neuro2a cells. Of the six transcription factors, ATF6β most strongly increased the MANF promoter activity via ERSE-II, while the effects of ATF6β and sXBP1 were moderate. However, overexpression of Luman or OASIS did not enhance ERSE-II-dependent MANF promoter activity in Neuro2a cells. To evaluate the relationships between transcription factors in the regulation of ERSE-II-dependent MANF promoter activity, we transfected two effective transcription factor constructs chosen from ATF6α, ATF6β, uXBP1 and sXBP1 into Neuro2a cells with the MANF reporter construct. The MANF promoter activity induced by co-transfection of ATF6α with ATF6β was significantly lower than that induced by ATF6α alone, while other combinations did not show any effect on the ERSE-II-dependent MANF promoter activity in Neuro2a cells. Our study is the first to show the efficiency of ER stress-related transcription factors for ERSE-II in activating the transcription of the mouse MANF gene in Neuro2a cells.

scholarly journals Inhibition of phosphatidylcholine synthesis induces expression of the endoplasmic reticulum stress and apoptosis-related protein CCAAT/enhancer-binding protein-homologous protein (CHOP/GADD153)

2003 ◽  
Vol 369 (3) ◽  
pp. 643-650 ◽  
Author(s):  
Michiel H.M. van der SANDEN ◽  
Martin HOUWELING ◽  
Lambert M.G. van GOLDE ◽  
Arie B. VAANDRAGER
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Er Stress ◽  
Binding Protein ◽  
Related Protein ◽  
Unfolded Proteins ◽  
Homologous Protein ◽  
Er Stress Response ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein

Inhibition of de novo synthesis of phosphatidylcholine (PC) by some anti-cancer drugs such as hexadecylphosphocholine leads to apoptosis in various cell lines. Likewise, in MT58, a mutant Chinese hamster ovary (CHO) cell line containing a thermo-sensitive mutation in CTP:phosphocholine cytidylyltransferase (CT), an important regulatory enzyme in the CDP-choline pathway, inhibition of PC synthesis causes PC depletion. Cellular perturbations like metabolic insults and unfolded proteins can be registered by the endoplasmic reticulum (ER) and result in ER stress responses, which can lead eventually to apoptosis. In this study we investigated the effect of PC depletion on the ER stress response and ER-related proteins. Shifting MT58 cells to the non-permissive temperature of 40°C resulted in PC depletion via an inhibition of CT within 24h. Early apoptotic features appeared in several cells around 30h, and most cells were apoptotic within 48h. The temperature shift in MT58 led to an increase of pro-apoptotic CCAAT/enhancer-binding protein-homologous protein (CHOP; also known as GADD153) after 16h, to a maximum at 24h. Incubation of wild-type CHO-K1 or CT-expressing MT58 cells at 40°C did not induce differences in CHOP protein levels in time. In contrast, expression of the ER chaperone BiP/GRP78, induced by an increase in misfolded/unfolded proteins, and caspase 12, a protease specifically involved in apoptosis that results from stress in the ER, did not differ between MT58 and CHO-K1 cells in time when cultured at 40°C. Furthermore, heat-shock protein 70, a protein that is stimulated by accumulation of abnormal proteins and heat stress, displayed similar expression patterns in MT58 and K1 cells. These results suggest that PC depletion in MT58 induces the ER-stress-related protein CHOP, without raising a general ER stress response.

Differential regulation of the ER stress response by long-chain fatty acids in the pancreatic β-cell

2008 ◽  
Vol 36 (5) ◽  
pp. 959-962 ◽  
Author(s):  
Eleftheria Diakogiannaki ◽  
Noel G. Morgan
Keyword(s):  
Fatty Acids ◽  
Stress Response ◽  
Er Stress ◽  
Unsaturated Fatty Acids ◽  
Initiation Factor ◽  
Long Chain Fatty Acids ◽  
Β Cells ◽  
Er Stress Response ◽  
Long Chain ◽  
Chain Fatty Acids

Recent evidence indicates that treatment of pancreatic β-cells with long chain fatty acids can lead to the development of an ER (endoplasmic reticulum) stress response. This is manifest as the activation of some components of the PERK [RNA-dependent protein kinase-like ER eIF2α (eukaryotic initiation factor 2α) kinase]-dependent arm of ER stress and is seen most dramatically when cells are treated with long-chain saturated fatty acids (e.g. palmitate). By contrast, the equivalent mono-unsaturates (e.g. palmitoleate) are much less effective and they can even attenuate the ER stress response to palmitate. This may be due to the regulation of eIF2α phosphorylation in cells exposed to mono-unsaturates. The present review discusses the differential effects of saturated and mono-unsaturated fatty acids on ER stress in β-cells and considers the extent to which regulation of this pathway may be involved in mediating their effects on viability.

scholarly journals Differential regulation of the endoplasmic reticulum stress response in pancreatic β-cells exposed to long-chain saturated and monounsaturated fatty acids

2008 ◽  
Vol 197 (3) ◽  
pp. 553-563 ◽  
Author(s):  
Eleftheria Diakogiannaki ◽  
Hannah J Welters ◽  
Noel G Morgan
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Er Stress ◽  
Initiation Factor ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Er Stress Response ◽  
Stress Pathway ◽  
Long Chain

Exposure of pancreatic β-cells to long-chain fatty acids leads to the activation of some components of the endoplasmic reticulum (ER) stress pathway and this mechanism may underlie the ability of certain fatty acids to promote β-cell death. We have studied ER stress in BRIN-BD11 β-cells exposed to either the saturated fatty acid palmitate (C16:0) or the monounsaturated palmitoleate (C16:1). Palmitate (0.025–0.25 mM) induced the expression of various markers of the RNA-dependent protein kinase-like ER eukaryotic initiation factor 2α (eIF2α) kinase (PERK)-dependent pathway of ER stress (phospho-eIF2α; ATF4, activating transcription factor 4 and C/EBP homologous protein (CHOP-10)) although it failed to promote the expression of the ER chaperone GRP78. By contrast, palmitoleate did not induce any markers of the ER stress pathway even at concentrations as high as 1 mM. When palmitate and palmitoleate were added in combination, a marked attenuation of the ER stress response occurred. Under these conditions, the levels of phospho-eIF2α, ATF4 and CHOP-10 were reduced to less than those found in control cells. Palmitoleate also attenuated the ER stress response to the protein glycosylation inhibitor, tunicamycin, and improved the viability of the cells exposed to this agent. Exposure of the BRIN-BD11 cells to the protein phosphatase inhibitor, salubrinal, in the absence of fatty acids resulted in increased eIF2α phosphorylation but this was abolished by co-incubation with palmitoleate. We conclude that saturated fatty acids activate components of the PERK-dependent ER stress pathway in β-cells, ultimately leading to increased apoptosis. This effect is antagonised by monounsaturates that may exert their anti-apoptotic actions by regulating the activity of one or more kinase enzymes involved in mediating the phosphorylation of eIF2α.

Targeted regulation of lymphocytic ER stress response with an overall immunosuppression to alleviate allograft rejection

Biomaterials ◽  
2021 ◽  
pp. 120757
Author(s):  
Yingying Shi ◽  
Yichao Lu ◽  
Chunqi Zhu ◽  
Zhenyu Luo ◽  
Xiang Li ◽  
...  
Keyword(s):  
Stress Response ◽  
Er Stress ◽  
Allograft Rejection ◽  
Er Stress Response

scholarly journals Highly Specialized Ubiquitin-Like Modifications: Shedding Light into the UFM1 Enigma

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 255
Author(s):  
Katharina F. Witting ◽  
Monique P.C. Mulder
Keyword(s):  
Dna Repair ◽  
Stress Response ◽  
Embryonic Development ◽  
Er Stress ◽  
Unmet Needs ◽  
Biological Function ◽  
Post Translational Modification ◽  
Er Stress Response ◽  
Cellular Events ◽  
Complex Signaling

Post-translational modification with Ubiquitin-like proteins represents a complex signaling language regulating virtually every cellular process. Among these post-translational modifiers is Ubiquitin-fold modifier (UFM1), which is covalently attached to its substrates through the orchestrated action of a dedicated enzymatic cascade. Originally identified to be involved embryonic development, its biological function remains enigmatic. Recent research reveals that UFM1 regulates a variety of cellular events ranging from DNA repair to autophagy and ER stress response implicating its involvement in a variety of diseases. Given the contribution of UFM1 to numerous pathologies, the enzymes of the UFM1 cascade represent attractive targets for pharmacological inhibition. Here we discuss the current understanding of this cryptic post-translational modification especially its contribution to disease as well as expand on the unmet needs of developing chemical and biochemical tools to dissect its role.

Sign in / Sign up

Export Citation Format

Share Document