Overexpression of calreticulin fails to abolish its induction by perturbation of normal ER function

1998 ◽  
Vol 76 (5) ◽  
pp. 875-880 ◽  
Author(s):  
David H Llewellyn ◽  
H Llewelyn Roderick
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Endoplasmic Reticulum Stress ◽  
Fusion Protein ◽  
Er Stress ◽  
Hela Cells ◽  
Mammalian Cells ◽  
Stress Signaling ◽  
Glucose Response ◽  
The Stability

Along with other endoplasmic reticulum (ER) Ca2+-binding proteins, notably the glucose-response proteins grp78 and grp94, expression of calreticulin is induced in response to perturbation of normal ER function. It has yet to be clearly defined how this stress is signaled from the ER to the nucleus in mammalian cells, particularly with regard to its initiation. Using a GFP-calreticulin fusion protein, we have generated and selected stably transfected HeLa cells that overexpress calreticulin to investigate whether the protein might be involved in signaling its own induction. Basal levels of endogenous calreticulin mRNA and protein were unaffected in these cells, indicating that overexpression alone does not induce a stress response. ER stress induced calreticulin expression in response to either thapsigargin or tunicamycin was equivalent in these cells to that seen in control, nontransfected cells, leading us to conclude that calreticulin is unlikely be involved in its own induction. Levels of the mRNA encoding the fusion protein were also increased by tunicamycin, but not thapsigargin, suggesting that, in agreement with our previous observations, inhibition of N-linked glycosylation may increase the stability of calreticulin mRNA. This indicates that in mammalian cells, there is more than one signaling pathway for the ER stress response.Key words: calreticulin, endoplasmic reticulum stress, signaling.

scholarly journals NOD1/NOD2 and RIP2 Regulate Endoplasmic Reticulum Stress-Induced Inflammation during Chlamydia Infection

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Oanh H. Pham ◽  
Bokyung Lee ◽  
Jasmine Labuda ◽  
A. Marijke Keestra-Gounder ◽  
Mariana X. Byndloss ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Inflammatory Response ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Young Women ◽  
The United States ◽  
Chlamydia Infection ◽  
Er Stress Response

ABSTRACT The inflammatory response to Chlamydia infection is likely to be multifactorial and involve a variety of ligand-dependent and -independent recognition pathways. We previously reported the presence of NOD1/NOD2-dependent endoplasmic reticulum (ER) stress-induced inflammation during Chlamydia muridarum infection in vitro, but the relevance of this finding to an in vivo context is unclear. Here, we examined the ER stress response to in vivo Chlamydia infection. The induction of interleukin 6 (IL-6) production after systemic Chlamydia infection correlated with expression of ER stress response genes. Furthermore, when tauroursodeoxycholate (TUDCA) was used to inhibit the ER stress response, an increased bacterial burden was detected, suggesting that ER stress-driven inflammation can contribute to systemic bacterial clearance. Mice lacking both NOD1 and NOD2 or RIP2 exhibited slightly higher systemic bacterial burdens after infection with Chlamydia. Overall, these data suggest a model where RIP2 and NOD1/NOD2 proteins link ER stress responses with the induction of Chlamydia-specific inflammatory responses. IMPORTANCE Understanding the initiation of the inflammatory response during Chlamydia infection is of public health importance given the impact of this disease on young women in the United States. Many young women are chronically infected with Chlamydia but are asymptomatic and therefore do not seek treatment, leaving them at risk of long-term reproductive harm due to inflammation in response to infection. Our manuscript explores the role of the endoplasmic reticulum stress response pathway initiated by an innate receptor in the development of this inflammation.

scholarly journals PRMT1 suppresses ATF4-mediated endoplasmic reticulum response in cardiomyocytes

2019 ◽  
Vol 10 (12) ◽  
Author(s):  
Myong-Ho Jeong ◽  
Hyeon-Ju Jeong ◽  
Byeong-Yun Ahn ◽  
Jung-Hoon Pyun ◽  
Ilmin Kwon ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Stress Response ◽  
Er Stress ◽  
Regulatory Mechanism ◽  
Critical Role ◽  
Mechanistic Study ◽  
Stress Signaling ◽  
Deficient Mutant ◽  
Er Stress Response

AbstractEndoplasmic reticulum (ER) stress signaling plays a critical role in the control of cell survival or death. Persistent ER stress activates proapoptotic pathway involving the ATF4/CHOP axis. Although accumulating evidences support its important contribution to cardiovascular diseases, but its mechanism is not well characterized. Here, we demonstrate a critical role for PRMT1 in the control of ER stress in cardiomyocytes. The inhibition of PRMT1 augments tunicamycin (TN)-triggered ER stress response in cardiomyocytes while PRMT1 overexpression attenuates it. Consistently, PRMT1 null hearts show exacerbated ER stress and cell death in response to TN treatment. Interestingly, ATF4 depletion attenuates the ER stress response induced by PRMT1 inhibition. The methylation-deficient mutant of ATF4 with the switch of arginine 239 to lysine exacerbates ER stress accompanied by enhanced levels of proapoptotic cleaved Caspase3 and phosphorylated-γH2AX in response to TN. The mechanistic study shows that PRMT1 modulates the protein stability of ATF4 through methylation. Taken together, our data suggest that ATF4 methylation on arginine 239 by PRMT1 is a novel regulatory mechanism for protection of cardiomyocytes from ER stress-induced cell death.

scholarly journals Global mRNA Stabilization Preferentially Linked to Translational Repression during the Endoplasmic Reticulum Stress Response

2004 ◽  
Vol 24 (15) ◽  
pp. 6773-6787 ◽  
Author(s):  
Tomoko Kawai ◽  
Jinshui Fan ◽  
Krystyna Mazan-Mamczarz ◽  
Myriam Gorospe
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Stress Response ◽  
Er Stress ◽  
Mrna Stability ◽  
Cdna Array ◽  
Mrna Turnover ◽  
Relative Distribution ◽  
Mrna Levels ◽  
The Stability

ABSTRACT The stability of mRNAs undergoing translation has long been a controversial question. Here, we systematically investigate links between mRNA turnover and translation during the endoplasmic reticulum (ER) stress response, a process during which protein synthesis is potently regulated. cDNA array-based approaches to assess the stability and translational status of each mRNA were devised. First, ER stress-triggered changes in mRNA stability were studied by comparing differences in steady-state mRNA levels with differences in gene transcription. Second, changes in translational status were monitored by studying ER stress-induced shifts in the relative distribution of each mRNA along sucrose gradients. Together, the array-derived data reveal complex links between mRNA stability and translation, with all regulatory groups represented: both stabilized and destabilized mRNAs were found among translationally induced as well as translationally suppressed mRNA collections. Remarkably, however, the subset of stabilized mRNAs was prominently enriched in translationally suppressed transcripts, suggesting that ER stress was capable of causing the stabilization of mRNAs associated with a global reduction in protein synthesis. The cDNA array-based approach described here can be applied to global analyses of mRNA turnover and translation and can serve to investigate subsets of mRNAs subject to joint posttranscriptional control.

scholarly journals Reduction of endoplasmic reticulum stress attenuates the defects caused by Drosophila mitofusin depletion

2014 ◽  
Vol 204 (3) ◽  
pp. 303-312 ◽  
Author(s):  
Valentina Debattisti ◽  
Diana Pendin ◽  
Elena Ziviani ◽  
Andrea Daga ◽  
Luca Scorrano
Keyword(s):  
Endoplasmic Reticulum ◽  
Drosophila Melanogaster ◽  
Endoplasmic Reticulum Stress ◽  
Fusion Protein ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Stress Reduction ◽  
Optic Atrophy ◽  
Regulatory Factor ◽  
Developmental Defects

Ablation of the mitochondrial fusion and endoplasmic reticulum (ER)–tethering protein Mfn2 causes ER stress, but whether this is just an epiphenomenon of mitochondrial dysfunction or a contributor to the phenotypes in mitofusin (Mfn)-depleted Drosophila melanogaster is unclear. In this paper, we show that reduction of ER dysfunction ameliorates the functional and developmental defects of flies lacking the single Mfn mitochondrial assembly regulatory factor (Marf). Ubiquitous or neuron- and muscle-specific Marf ablation was lethal, altering mitochondrial and ER morphology and triggering ER stress that was conversely absent in flies lacking the fusion protein optic atrophy 1. Expression of Mfn2 and ER stress reduction in flies lacking Marf corrected ER shape, attenuating the developmental and motor defects. Thus, ER stress is a targetable pathogenetic component of the phenotypes caused by Drosophila Mfn ablation.

An update on lipotoxic endoplasmic reticulum stress in pancreatic β-cells

2008 ◽  
Vol 36 (5) ◽  
pp. 909-915 ◽  
Author(s):  
Miriam Cnop ◽  
Mariana Igoillo-Esteve ◽  
Daniel A. Cunha ◽  
Laurence Ladrière ◽  
Décio L. Eizirik
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Endoplasmic Reticulum Stress Response ◽  
Cell Recovery ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Peripheral Tissues ◽  
Unfolded Protein

The UPR (unfolded protein response) or ER (endoplasmic reticulum) stress response was first described 20 years ago. The field of ER stress has expanded tremendously since, moving from basic biology in yeast to human neurodegenerative, inflammatory, cardiovascular and neoplastic diseases. The ER stress response has also been implicated in diabetes development, affecting both insulin production by pancreatic β-cells and insulin sensitivity in peripheral tissues. In the present mini-review, we focus on recent progress in the field of ER stress in pancreatic β-cells. Recent advances in the understanding of lipotoxic ER stress and β-cell recovery from ER stress are discussed.

scholarly journals Melatonin Improves Endoplasmic Reticulum Stress-Mediated IRE1α Pathway in Zücker Diabetic Fatty Rat

2021 ◽  
Vol 14 (3) ◽  
pp. 232
Author(s):  
Samira Aouichat ◽  
Miguel Navarro-Alarcon ◽  
Pablo Alarcón-Guijo ◽  
Diego Salagre ◽  
Marwa Ncir ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Kidney Disease ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Amino Terminal ◽  
Er Stress Response ◽  
Obesity And Diabetes ◽  
Renal Morphology ◽  
Zdf Rats

Obesity and diabetes are linked to an increased prevalence of kidney disease. Endoplasmic reticulum stress has recently gained growing importance in the pathogenesis of obesity and diabetes-related kidney disease. Melatonin, is an important anti-obesogenic natural bioactive compound. Previously, our research group showed that the renoprotective effect of melatonin administration was associated with restoring mitochondrial fission/fusion balance and function in a rat model of diabesity-induced kidney injury. This study was carried out to further investigate whether melatonin could suppress renal endoplasmic reticulum (ER) stress response and the downstream unfolded protein response activation under obese and diabetic conditions. Zücker diabetic fatty (ZDF) rats and lean littermates (ZL) were orally supplemented either with melatonin (10 mg/kg body weight (BW)/day) (M–ZDF and M–ZL) or vehicle (C–ZDF and C–ZL) for 17 weeks. Western blot analysis of ER stress-related markers and renal morphology were assessed. Compared to C–ZL rats, higher ER stress response associated with impaired renal morphology was observed in C–ZDF rats. Melatonin supplementation alleviated renal ER stress response in ZDF rats, by decreasing glucose-regulated protein 78 (GRP78), phosphoinositol-requiring enzyme1α (IRE1α), and ATF6 levels but had no effect on phospho–protein kinase RNA–like endoplasmic reticulum kinase (PERK) level. In addition, melatonin supplementation also restrained the ER stress-mediated apoptotic pathway, as indicated by decreased pro-apoptotic proteins phospho–c–jun amino terminal kinase (JNK), Bax, and cleaved caspase-3, as well as by upregulation of B cell lymphoma (Bcl)-2 protein. These improvements were associated with renal structural recovery. Taken together, our findings revealed that melatonin play a renoprotective role, at least in part, by suppressing ER stress and related pro-apoptotic IRE1α/JNK signaling pathway.

CD125-Expressing Myeloma: A Subgroup of Multiple Myeloma (MM) with Immature Phenotype, Endoplasmic Reticulum Stress Response and Low Sensitivity to Bortezomib

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 616-616
Author(s):  
Yawara Kawano ◽  
Yoshitaka Kikukawa ◽  
Miki Nakamura ◽  
Yutaka Okuno ◽  
Hiromichi Yuki ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Stress Response ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Surface Antigen ◽  
High Expression ◽  
Expression Level ◽  
Er Stress Response ◽  
The Mean ◽  
Low Sensitivity

Abstract Abstract 616 Introduction Although marked heterogeneity in phenotypes of MM is known, classification of MM based on molecular expressions remains to be determined. During analysis of microarray data utilizing purified MM cells obtained from bortezomib-sensitive and resistant cases, we identified a 100-fold higher expression of CD125 in bortezomib-resistant MM cells. Because CD125, also known as interleukin-5 receptor alpha chain, is expressed on mature B cells undergoing class switch recombination, the existence of CD125 in MM cells may suggest that MM cells are at a less mature differentiation stage than plasma cells. We further tried to classify MM patients by analyzing correlations of CD125-expressions with other surface antigen expressions and endoplasmic reticulum stress (ER stress) response: the latter plays a crucial role in resistance to bortezomib. Correlation of CD125 expression with sensitivity to bortezomib therapy was also evaluated. Materials and Methods Bone marrow samples were obtained from MM patients under written informed consentaccording to Helsinki Declaration and processed for purification using CD138 immunomagnetic beads. Expressions of CD125 and spliced-XBP-1 (spliced-XBP-1 presence is a hallmark of activated ER stress response), were evaluated using real time PCR. Flowcytometry analysis was performed using gating CD38 bright population at SRL laboratory Inc. (Tokushima, Japan). Response to bortezomib was assessed according to the international myeloma working group criteria. Results CD125 expression was found in MM cells at various levels. When it was compared to other surface antigen expressions, MM cells with expression of CD125 tend to express both CD20 and CD45 (p<0.05). Expression of CD125 also correlated with high expression levels of XBP-1s (Figure 1, p<0.01). The mean expression level of CD125 in bortezomib resistant cases was 6.17 fold greater than that in sensitive cases (110.6 versus 17.9, respectively, p<0.05). The mean expression level of XBP-1s in bortezomib-resistant cases was 2.3-fold greater than that in sensitive cases (p=0.06), which might suggest a role of ER stress in the regulation of sensitivity to bortezomib, while further detailed study should be required. Conclusions The present results suggest that CD125-expression in MM may represent a distinctive disease marker, which features immature phenotype, high ER stress response, and low sensitivity to bortezomib. High expression of XBP-1s in bortezomib-resistant cases suggests that the existence of ER stress response prior to bortezomib exposure may be responsible for poor response to bortezomib. Further analysis of CD125-positive MM cells is important for clarifying tumorigenesis at early stages of B-cell differentiation and possibly developing a new therapeutic strategy targeting ER stress. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Cellular Mechanisms of Endoplasmic Reticulum Stress Signaling in Health and Disease. 2. Protein misfolding and ER stress

2014 ◽  
Vol 307 (8) ◽  
pp. C657-C670 ◽  
Author(s):  
Joseph E. Chambers ◽  
Stefan J. Marciniak
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Protein Misfolding ◽  
Secretory Cells ◽  
Stress Signaling ◽  
Cellular Mechanisms ◽  
Major Site ◽  
Health And Disease

The endoplasmic reticulum (ER) is a major site of protein synthesis, most strikingly in the specialized secretory cells of metazoans, which can produce their own weight in proteins daily. Cells possess a diverse machinery to ensure correct folding, assembly, and secretion of proteins from the ER. When this machinery is overwhelmed, the cell is said to experience ER stress, a result of the accumulation of unfolded or misfolded proteins in the lumen of the organelle. Here we discuss the causes of ER stress and the mechanisms by which cells elicit a response, with an emphasis on recent discoveries.

Use of Uranium-Labeled Antibodies for Electron Microscopic Localization of Various Antigens in Mammalian Cells

1967 ◽  
Vol 25 ◽  
pp. 136-137
Author(s):  
J. P. Petrali ◽  
E. J. Donati ◽  
L. A. Sternberger
Keyword(s):  
Endoplasmic Reticulum ◽  
Hela Cells ◽  
Mammalian Cells ◽  
Specific Antiserum ◽  
Electron Microscopic ◽  
E Coli ◽  
Cytoplasmic Membranes ◽  
Viral Progeny ◽  
Ultrathin Sections ◽  
Electron Microscopic Localization

Specific contrast is conferred to subcellular antigen by applying purified antibodies, exhaustively labeled with uranium under immunospecific protection, to ultrathin sections. Use of Seligman’s principle of bridging osmium to metal via thiocarbohydrazide (TCH) intensifies specific contrast. Ultrathin sections of osmium-fixed materials were stained on the grid by application of 1) thiosemicarbazide (TSC), 2) unlabeled specific antiserum, 3) uranium-labeled anti-antibody and 4) TCH followed by reosmication. Antigens to be localized consisted of vaccinia antigen in infected HeLa cells, lysozyme in monocytes of patients with monocytic or monomyelocytic leukemia, and fibrinogen in the platelets of these leukemic patients. Control sections were stained with non-specific antiserum (E. coli).In the vaccinia-HeLa system, antigen was localized from 1 to 3 hours following infection, and was confined to degrading virus, the inner walls of numerous organelles, and other structures in cytoplasmic foci. Surrounding architecture and cellular mitochondria were unstained. 8 to 14 hours after infection, antigen was localized on the outer walls of the viral progeny, on cytoplasmic membranes, and free in the cytoplasm. Staining of endoplasmic reticulum was intense and focal early, and weak and diffuse late in infection.

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