Elucidation of ER stress and UPR pathway in sialic acid‐deficient cells: Pathological relevance to GNEM

2021 ◽  
Author(s):  
Priyanka Chaudhary ◽  
Shweta Sharma ◽  
Reema Singh ◽  
Ranjana Arya
Keyword(s):  
Sialic Acid ◽  
Er Stress ◽  
Upr Pathway

scholarly journals Involvement of ER stress in apoptosis induced by sialic acid-binding lectin (leczyme) from bullfrog eggs

2013 ◽  
Vol 43 (6) ◽  
pp. 1799-1808 ◽  
Author(s):  
TAKEO TATSUTA ◽  
MASAHIRO HOSONO ◽  
YUKI MIURA ◽  
SHIGEKI SUGAWARA ◽  
YUKIKO KARIYA ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Er Stress ◽  
Sialic Acid Binding ◽  
Binding Lectin

scholarly journals Genetic Evidence for a Role of BiP/Kar2 That Regulates Ire1 in Response to Accumulation of Unfolded Proteins

2003 ◽  
Vol 14 (6) ◽  
pp. 2559-2569 ◽  
Author(s):  
Yukio Kimata ◽  
Yuki I. Kimata ◽  
Yusuke Shimizu ◽  
Hiroshi Abe ◽  
Ileana C. Farcasanu ◽  
...  
Keyword(s):  
Er Stress ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Unfolded Proteins ◽  
Direct Role ◽  
Signaling Mechanism ◽  
Potent Inducer ◽  
The Unfolded Protein Response ◽  
Regulation Model ◽  
Upr Pathway

In the unfolded protein response (UPR) signaling pathway, accumulation of unfolded proteins in the endoplasmic reticulum (ER) activates a transmembrane kinase/ribonuclease Ire1, which causes the transcriptional induction of ER-resident chaperones, including BiP/Kar2. It was previously hypothesized that BiP/Kar2 plays a direct role in the signaling mechanism. In this model, association of BiP/Kar2 with Ire1 represses the UPR pathway while under conditions of ER stress, BiP/Kar2 dissociation leads to activation. To test this model, we analyzed five temperature-sensitive alleles of the yeast KAR2 gene. When cells carrying a mutation in the Kar2 substrate-binding domain were incubated at the restrictive temperature, association of Kar2 to Ire1 was disrupted, and the UPR pathway was activated even in the absence of extrinsic ER stress. Conversely, cells carrying a mutation in the Kar2 ATPase domain, in which Kar2 poorly dissociated from Ire1 even in the presence of tunicamycin, a potent inducer of ER stress, were unable to activate the pathway. Our findings provide strong evidence in support of BiP/Kar2-dependent Ire1 regulation model and suggest that Ire1 associates with Kar2 as a chaperone substrate. We speculate that recognition of unfolded proteins is based on their competition with Ire1 for binding with BiP/Kar2.

scholarly journals Overcoming Resistance to Apoptosis in Multiple Myeloma By Simultaneous Inhibition of Bcl2 and IAP Families of Anti-Apoptotic Proteins

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2088-2088
Author(s):  
Marcus Gomez ◽  
Vijay G. Ramakrishnan ◽  
Vivek Prasad ◽  
Teresa K. Kimlinger ◽  
Utkarsh Painuly ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Cell Death ◽  
Er Stress ◽  
Cell Lines ◽  
Bcl2 Family ◽  
Er Stress Response ◽  
Simultaneous Inhibition ◽  
Apoptotic Proteins ◽  
Upr Pathway

Abstract Background: Multiple myeloma (MM) cells evade apoptosis through multiple mechanisms thus enabling it to evade therapy. The Bcl2 family of anti-apoptotic proteins is aberrantly expressed in MM cell lines and patient cells. Yet, pharmacological intervention of this family appears to have significant activity only in molecular subgroups of MM patients. This clearly suggests alternate mechanisms of overcoming apoptotic signals in MM cells in addition to the Bcl2 family, through proteins such as IAPs. We have previously shown that simultaneous inhibition of the three major IAP proteins, namely cIAP1, cIAP2 and XIAP is required to induce pronounced apoptosis in MM cells. However, IAP inhibition results in apoptosis in only some MM cell lines and patient cells. Given that levels of Bcl2 family proteins are unaffected by IAP inhibition, we hypothesized that combined inhibition of the IAP proteins using a SMAC mimetic LCL161 and the Bcl2 family proteins using a pan-Bcl2 inhibitor obatoclax (OBX) will lead to more pronounced and synergistic cell death in a broader subgroup of MM patients. Methods: LCL161 was synthesized by Novartis Inc. (Basel, Switzerland). OBX was purchased from Selleckchem (Houston, USA). Stock solutions were made in DMSO, and subsequently diluted in RPMI-1640 medium for use. MM cell lines were cultured in RPMI 1640 containing 10% fetal bovine serum (20% serum for primary patient cells) supplemented with L-Glutamine, penicillin, and streptomycin. Cytotoxicity was measured using the MTT viability assay and proliferation using thymidine uptake. Apoptosis was measured using flow cytometry upon cell staining with Annexin V-FITC and propidium iodide (PI) for cell lines and patient cells. Immunoblotting was done on cell extracts at various time points following incubation with the drugs in order to study the cell signaling pathways and a Results: LCL161/OBX combination induced synergistic cytotoxicity and anti-proliferative effects on a broad range of human MM cell lines, including drug resistant cell lines like DOX40 and MM1R. Components of the bone marrow microenvironment including bone marrow stromal cells and tumor promoting cytokines (VEGF, IGF and IL6) were unable to protect MM cells from the effects of the drug combination. We saw a time dependent increase in apoptosis, with the combination inducing significantly more apoptosis than either of the single agents alone. Examining the mechanism of action of the drug combination showed clear inhibition of the IAP proteins, activation of caspases 9, 8, 3 and Bid by LCL161 and the combination and up regulation of the pro-apoptotic proteins Bim, Bid, Puma and Noxa and accumulation of LC3-II by OBX and the combination. Using chloroquine along with the OBX, we were able to demonstrate that OBX induced protective autophagy and the addition of LCL161 was able to overcome this protective effect induced after single agent OBX treatment. Since protective autophagy can be induced by the ER stress response, we then examined the expression levels of proteins involved in this pathway. We observed clear induction of ER stress mediated UPR pathway by both the drugs. However, LCL161 and OBX induced different branches of the UPR pathway. OBX activated the ATF6 and pErk/peif2α/ATF4 branches of the UPR, both of which have been implicated in cell survival during ER stress. ATF4 under irrecoverable ER stress can lead to increase in transcription of CHOP and cause apoptosis. We therefore examined levels of CHOP and observed no induction of CHOP post treatment with either of the drugs or the combination. LCL161, however differentially modulated the IRE1 branch of the UPR by down regulating Xbp-1 splicing, which is a pro survival activity of IREI and up regulating pJNK, which indicated a pro-apoptotic activity induced by IRE1 post irrecoverable ER stress This indicated that the ER stress induced apoptosis is triggered by LCL161, which might be important to overcome the ER induced protective effects induced by OBX. Conclusion: Taken together, our studies indicate that LCL161/OBX combination induces synergistic cell death through modulation of apoptosis, authophagy and the ER stress response. Disclosures No relevant conflicts of interest to declare.

Andrographolide Mitigates Unfolded Protein Response Pathway andApoptosis Involved in Chikungunya virus Infection

2020 ◽  
Vol 23 ◽  
Author(s):  
Swati Gupta ◽  
KP Mishra ◽  
Bhuvnesh Kumar ◽  
SB Singh ◽  
Lilly Ganju
Keyword(s):  
Protein Expression ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Chikungunya Virus ◽  
Rna Virus ◽  
Apoptosis Pathway ◽  
Unfolded Protein ◽  
Induced Apoptosis ◽  
Protein Response ◽  
Upr Pathway

Background: Chikungunya virus (CHIKV) is an arthropod-borne RNA virus which induces host endoplasmic reticulum (ER) stress by accumulating unfolded or misfolded proteins. ER stress activates the unfolded protein response (UPR) pathway to enable proper protein folding and maintain cellular homeostasis. There is no approved drug or vaccine available for CHIKV treatment, therefore, a pharmacological countermeasure is warranted for preventing CHIKV infection. Objective: With a view to find a treatment modality for chikungunya infection, “andrographolide”; a plant-derived diterpenoid with reported antiviral, anti-inflammatory and immunomodulatory effects, was used to investigate its role in chikungunya induced unfolded protein stress and apoptosis. Methods: Cells and supernatant collected on andrographolide and VER-155008; a GRP78 inhibitor, treatment in CHIKV infected and mock-infected THP-1 cells were tested for differential expression of UPR pathway proteins including GRP78, PERK, EIF-2α, IRE-1α, XBP-1 and ATF6. Further, the inflammasome and apoptosis pathway proteins i.e. caspase-1, caspase-3 and PARP were tested by immunoblotting and cytokines i.e. IL-1β, IL-6 and IFN-γ were tested by ELISA. Results: Andrographolide treatment in CHIKV infected THP-1 cells significantly reduced IRE1α and downstream spliced XBP1 protein expression. Further, CHIKV induced apoptosis and viral protein expression was also reduced on andrographolide treatment. A comparative analysis of andrographolide verses VER-155008, confirmed that andrographolide surpasses the effects of VER-155008 in suppressing the CHIKV induced ER stress. Conclusion: The study, therefore, confirms that andrographolide is a potential remedy for chikungunya infection and suppresses CHIKV induced ER stress and apoptosis.

scholarly journals Screening The Efficacy of Melatonin On Neurodegeneration Mediated By ER Stress, Inflammation And Oxidative Damage

2021 ◽  
Author(s):  
Fathima Hajee Basha ◽  
S. Hemalatha
Keyword(s):  
Circadian Rhythm ◽  
Oxidative Damage ◽  
Er Stress ◽  
Neurodegenerative Disorders ◽  
Structural Integrity ◽  
Molecular Targets ◽  
Therapeutic Strategies ◽  
Functional Abilities ◽  
Mitochondrial Defects ◽  
Upr Pathway

Abstract Neurodegeneration may be defined as a clinical condition wherein neurons gradually lose their structural integrity, viability, functional abilities and the damage inflicted upon the neurons is often irreversible. The number of elderly patients suffering from Neurodegenerative disorders is expected to rise tremendously over the next couple of years. Thus, there is an urgent need to delve into and study the underlying cause and mechanisms, so that we may be able to develop more effective therapeutic strategies and drugs and better understand the origin and progression of the disease.The various mechanisms that have been observed to contribute to neurodegeneration include aggregation and accumulation of misfolded proteins, impaired autophagy, oxidative damage, neuroinflammation, mitochondrial defects, increased SUMOylation of proteins, impaired UPR pathways, disruption of axonal transport.Melatonin, a neurohormone is involved in a variety of functions including scavenging free radicals, synchronizing the circadian rhythm, mitigating immune response.Melatonin has shown to modulate the UPR pathway ,antioxidant pathway through Nrf2 and inflammatory pathway through NFκB. The study aims to determine the efficacy of melatonin on neurodegeneration mediated by ER stress, inflammation and oxidative damage through in silico approaches. The molecular targets chosen were ATF6, XBP1, PERK, Nrf2, NFκB and they were docked against melatonin. Additionally various physiochemical analysis such as ADME were also carried out to determine its drug ability. The findings were that melatonin not only shows excellent interactions with the targets but also possess drug-like physicochemical properties that makes it a valuable choice for the treatment of neurodegenerative disorders.

scholarly journals Prototype foamy virus elicits complete autophagy involving the ER stress-related UPR pathway

Retrovirology ◽  
2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Peipei Yuan ◽  
Lanlan Dong ◽  
Qingqing Cheng ◽  
Shuang Wang ◽  
Zhi Li ◽  
...  
Keyword(s):  
Er Stress ◽  
Foamy Virus ◽  
Prototype Foamy Virus ◽  
Upr Pathway

scholarly journals In vitro Anticancer Effects of JI017 on Two Prostate Cancer Cell Lines Involve Endoplasmic Reticulum Stress Mediated by Elevated Levels of Reactive Oxygen Species

2021 ◽  
Vol 12 ◽  
Author(s):  
Min Jeong Kim ◽  
Jin Mo Ku ◽  
Se Hyang Hong ◽  
Hyo In Kim ◽  
Yun Young Kwon ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Reactive Oxygen Species ◽  
Er Stress ◽  
Cancer Cells ◽  
Human Prostate ◽  
Oxygen Species ◽  
Human Prostate Cancer ◽  
Prostate Cancer Cells ◽  
Anticancer Effects ◽  
Upr Pathway

Prostate cancer is the second most commonly diagnosed cancer, and prostate cancer is the second most common cause of cancer death in United States men after lung cancer. Many therapies are used to treat prostate cancer, and chemotherapy is one of the most relevant treatments. However, chemotherapy has many side effects, and repeated administration of chemotherapeutic agents leads to acquired resistance. Thus, new drugs with few side effects are needed. We investigated the molecular mechanism of action of JI017 in human prostate cancer cells. We identified an endoplasmic reticulum (ER) stress pathway that depended on the reactive oxygen species (ROS) pathway and played a crucial role in JI017-induced apoptosis. We measured cell viability by the MTS assay to determine the effect of JI017. Analysis of apoptosis, mitochondrial dysfunction, and cell cycle features was performed by flow cytometry. We used western blot and RT-PCR to measure the levels of the proteins of the unfolded protein response (UPR) pathway and apoptosis markers. Immunoprecipitation assay and transfection were used to determine the expression levels of proteins interacting with the pathways influenced by JI017 in prostate cancer cells. The anticancer effects induced by JI017 were evaluated. JI017 induced cell death that regulated apoptotic molecules and caused cell cycle arrest that inhibited the proliferation of cancer cells. Moreover, JI017 generated ROS. Accumulation of ROS caused ER stress through the PERK–eIF2α–CHOP and IRE1α-CHOP pathways. Furthermore, persistent activation of the UPR pathway induced by JI017 treatment triggered mitochondrial dysfunction, including dissipation of mitochondrial membrane potential, which activated intrinsic apoptotic pathway in human prostate cancer cells. The data indicated that N-acetyl-L-cysteine diminished apoptosis. We demonstrated that JI017 induced ER stress and cell death. Anticancer properties of JI017 in prostate cancer cells and in a human prostate cancer model involved ROS-mediated ER stress. Thus, JI017 treatment provides a new strategy for chemotherapy of prostate cancer.

Abstract 210: Flavin Containing Monooxygenase 2 Confers Cardiac Protection via Unfolded Protein Response Signaling Modulated by Disulfide Bond Catalysis

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_4) ◽  
Author(s):  
Qingnian Liu ◽  
Yue Tao ◽  
Hao Ding ◽  
Changchen Xiao ◽  
Yu Zhou ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Cardiac Function ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Disulfide Bond ◽  
Active Site ◽  
Cardiac Protection ◽  
Unfolded Protein ◽  
Protein Response ◽  
Upr Pathway

Introduction: Myocardial infarction (MI) is characterized by cardiac dysfunction and increased cardiomyocyte death, induced mainly by apoptosis. Using an unbiased transcriptome analysis, we identified flavin containing monooxygenase 2 (FMO2) as one of the top-ranked genes involved in the process of MI. In this study, we investigate the roles of FMO2 in ischemic injury and its potential mechanisms. Hypothesis: FMO2 exhibits the cardiac protection from MI injury. Methods: Male SD rats receiving either adeno-associated virus serotype 9 containing FMO2 shRNA particles (AAV-shFMO2) or FMO2 (AAV-FMO2), and FMO2 knockout rats were subjected to myocardial infarction surgery. Cardiac function, fibrosis, and apoptosis were examined in these rats and related cellular and molecular mechanisms were investigated. Results: Cardiac ischemia injury was associated with significant increases of FMO2 levels both in ex vivo and in vivo models. Loss of FMO2 significantly enhanced cardiomyocyte apoptosis and deteriorated cardiac function accompanied by augmented infarct size in infarcted rat hearts, while elevated expression of FMO2 exhibited the opposite results. Mechanically, located on the ER membrane, FMO2 inhibited activation of ER stress-initiated apoptotic proteins including caspase 12 and C/EBP homologous protein (CHOP), via down-regulating upstream unfolded protein response (UPR) pathway. Furthermore, we found that FMO2, as a novel chaperone in ER, directly catalyzed disulfide-bond synthesis to facilitate proteins folding. Finally, structure analysis of FMO2 revealed the active site GVSG for disulfide-bond catalysis, which was confirmed by the molecular docking experiment of GSH with FMO2. However, FMO2 with GVSG mutation failed to catalyze disulfide-bond formation and lost protection from ER stress or apoptosis in cardiomyocytes. Conclusion: FMO2 confers cardiac protection from ischemic damage due to improved cardiomyocyte apoptosis through UPR pathway, which is mediated by disulfide-bond catalysis at GVSG active site. Our findings uncover a novel FMO2-involved regulatory mechanism which could serves as a potential therapeutic target for ischemic cardiovascular diseases.

scholarly journals Stbd1 promotes glycogen clustering during endoplasmic reticulum stress and supports survival of mouse myoblasts

2020 ◽  
Vol 133 (20) ◽  
pp. jcs244855
Author(s):  
Andria A. Lytridou ◽  
Anthi Demetriadou ◽  
Melina Christou ◽  
Louiza Potamiti ◽  
Nikolas P. Mastroyiannopoulos ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Myogenic Differentiation ◽  
Apoptotic Pathway ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Glucose Restriction ◽  
Protein Response ◽  
Er Homeostasis ◽  
Upr Pathway

ABSTRACTImbalances in endoplasmic reticulum (ER) homeostasis provoke a condition known as ER stress and activate the unfolded protein response (UPR) pathway, an evolutionarily conserved cell survival mechanism. Here, we show that mouse myoblasts respond to UPR activation by stimulating glycogenesis and the formation of α-amylase-degradable, glycogen-containing ER structures. We demonstrate that the glycogen-binding protein Stbd1 is markedly upregulated through the PERK signalling branch of the UPR pathway and is required for the build-up of glycogen structures in response to ER stress activation. In the absence of ER stress, Stbd1 overexpression is sufficient to induce glycogen clustering but does not stimulate glycogenesis. Glycogen structures induced by ER stress are degraded under conditions of glucose restriction through a process that does not depend on autophagosome–lysosome fusion. Furthermore, we provide evidence that failure to induce glycogen clustering during ER stress is associated with enhanced activation of the apoptotic pathway. Our results reveal a so far unknown response of mouse myoblasts to ER stress and uncover a novel specific function of Stbd1 in this process, which may have physiological implications during myogenic differentiation.This article has an associated First Person interview with the first author of the paper.

scholarly journals GNRH Induces the Unfolded Protein Response in the LβT2 Pituitary Gonadotrope Cell Line

2009 ◽  
Vol 23 (1) ◽  
pp. 100-112 ◽  
Author(s):  
Minh-Ha T. Do ◽  
Sharon J. Santos ◽  
Mark A. Lawson
Keyword(s):  
Er Stress ◽  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Eukaryotic Translation ◽  
Unfolded Protein ◽  
Eukaryotic Translation Initiation ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Upr Pathway

The neuropeptide GNRH 1 stimulates the secretion of the reproductive hormone LH in pituitary gonadotropes. Other secretory cell types depend on the unfolded protein response (UPR) pathway to regulate protein synthesis and protect against endoplasmic reticulum (ER) stress in response to differentiation or secretory stimuli. This study investigated the role of the UPR in GNRH action within the LβT2 gonadotrope model. Cells were treated with GNRH, and the activation of UPR signaling components and general translational status was examined. The ER-resident stress sensors, Atf6, Eif2ak3, and Ern1, are all present, and GNRH stimulation results in the phosphorylation of eukaryotic translation initiation factor 2A kinase 3 and its downstream effector, eukaryotic translation initiation factor 2A. Additionally, activation of the UPR was confirmed both in LβT2 as well as mouse primary pituitary cells through identifying GNRH-induced splicing of Xbp1 mRNA, a transcription factor activated by splicing by the ER stress sensor, ER to nucleus signaling 1. Ribosome profiling revealed that GNRH stimulation caused a transient attenuation in translation, a hallmark of the UPR, remodeling ribosomes from actively translating polysomes to translationally inefficient ribonucleoprotein complexes and monosomes. The transient attenuation of specific mRNAs was also observed. Overall, the results show that GNRH activates components of the UPR pathway, and this pathway may play an important physiological role in adapting the ER of gonadotropes to the burden of their secretory demand.

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