Crocin and quercetin prevent PAT-induced apoptosis in mammalian cells: Involvement of ROS-mediated ER stress pathway

Asymmetric dimethylarginine (ADMA), an inhibitor of nitric oxide synthase, is a novel risk factor of cardiovascular disease. Endothelial progenitor cells (EPCs) bear typical endothelial characteristics and are thought to contribute to neovascularization by providing new endothelial cells (ECs) after arterial injury. Many studies have shown that ADMA can induce EPC apoptosis and dysfunction, but the underlying mechanism is not well understood. EPCs from umbilical cord blood were cultured in EGM-2 medium with particular growth factors and supplemented with 10% fetal bovine serum. The cells were treated with different concentrations of ADMA (5, 10, and 50 μmol/L). Endoplasmic reticulum (ER) stress marker levels were examined by western blot analysis. After 24-hour incubation, ADMA induced apoptosis of EPCs and significantly decreased the proliferation, migration, and vasculogenesis capacity of EPCs. We also found that ADMA treatment activated phosphorylated protein kinase RNA-activated-like ER kinase (PERK), a stress sensor protein in the endoplasmic reticulum (ER). The activated PERK induced 78 kDa glucose-regulated protein (GRP-78) and C/EBP homologous protein (CHOP) expression. Additionally, the inhibition of the ER stress pathway by Salubrinal (a specific ER stress inhibitor) can attenuate ADMA-induced apoptosis of EPCs. Overall, these observations indicate that ADMA may induce the apoptosis and dysfunction of EPCs through the ER stress pathway.

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A Systems Approach to ER Stress Pathway Dynamics Reveals the Impact of Freeze-Dried Broccoli Extract to Mitigate Inflammation in Human Adipocytes through the Mevalonate Pathway

Diabetes ◽

10.2337/db18-2076-p ◽

2018 ◽

Vol 67 (Supplement 1) ◽

pp. 2076-P

Author(s):

ALICE MURPHY ◽

SAHAR AZHARIAN ◽

GYANENDRA TRIPATHI ◽

GUY BARKER ◽

MICHAEL J. CHAPPELL ◽

...

Keyword(s):

Er Stress ◽

Systems Approach ◽

Mevalonate Pathway ◽

Human Adipocytes ◽

Freeze Dried ◽

The Impact ◽

Stress Pathway

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5-ALA Attenuates the Palmitic Acid-Induced ER Stress and Apoptosis in Bovine Mammary Epithelial Cells

Molecules ◽

10.3390/molecules26041183 ◽

2021 ◽

Vol 26 (4) ◽

pp. 1183

Author(s):

Mst Mamuna Sharmin ◽

Md Aminul Islam ◽

Itsuki Yamamoto ◽

Shin Taniguchi ◽

Shinichi Yonekura

Keyword(s):

T Cells ◽

Epithelial Cells ◽

Palmitic Acid ◽

Er Stress ◽

Aminolevulinic Acid ◽

Mammary Epithelial Cells ◽

Mammary Epithelial ◽

Protective Effects ◽

Bovine Mammary Epithelial Cells ◽

Induced Apoptosis

The conservation of mammary gland physiology by maintaining the maximum number of mammary epithelial cells (MECs) is of the utmost importance for the optimum amount of milk production. In a state of negative energy balance, palmitic acid (PA) reduces the number of bovine MECs. However, there is no effective strategy against PA-induced apoptosis of MECs. In the present study, 5-aminolevulinic acid (5-ALA) was established as a remedial agent against PA-induced apoptosis of MAC-T cells (an established line of bovine MECs). In PA-treated cells, the apoptosis-related genes BCL2 and BAX were down- and upregulated, respectively. The elevated expression of major genes of the unfolded protein response (UPR), such as CHOP, a proapoptotic marker (C/EBP homologous protein), reduced the viability of PA-treated MAC-T cells. In contrast, 5-ALA pretreatment increased and decreased BCL2 and BAX expression, respectively. Moreover, cleaved caspase-3 protein expression was significantly reduced in the 5-ALA-pretreated group in comparison with the PA group. The downregulation of major UPR-related genes, including CHOP, extended the viability of MAC-T cells pretreated with 5-ALA and also reduced the enhanced intensity of the PA-induced expression of phospho-protein kinase R-like ER kinase. Moreover, the enhanced expression of HO-1 (antioxidant gene heme oxygenase) by 5-ALA reduced PA-induced oxidative stress (OxS). HO-1 is not only protective against OxS but also effective against ER stress. Collectively, these findings offer new insights into the protective effects of 5-ALA against PA-induced apoptosis of bovine MECs.

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Glutathione peroxidase-1 regulates ASK1-dependent apoptosis via interaction with TRAF2 in RIPK3-negative cancer cells

Experimental & Molecular Medicine ◽

10.1038/s12276-021-00642-7 ◽

2021 ◽

Author(s):

Sunmi Lee ◽

Eun-Kyung Lee ◽

Dong Hoon Kang ◽

Jiyoung Lee ◽

Soo Hyun Hong ◽

...

Keyword(s):

Glutathione Peroxidase ◽

Cancer Cells ◽

Mammalian Cells ◽

Apoptosis Pathway ◽

Glutathione Peroxidase 1 ◽

Peroxidase Enzyme ◽

Thioredoxin 1 ◽

Sequential Activation ◽

Induced Apoptosis

AbstractGlutathione peroxidase (GPx) is a selenocysteine-containing peroxidase enzyme that defends mammalian cells against oxidative stress, but the role of GPx signaling is poorly characterized. Here, we show that GPx type 1 (GPx1) plays a key regulatory role in the apoptosis signaling pathway. The absence of GPx1 augmented TNF-α-induced apoptosis in various RIPK3-negative cancer cells by markedly elevating the level of cytosolic H2O2, which is derived from mitochondria. At the molecular level, the absence of GPx1 led to the strengthened sequential activation of sustained JNK and caspase-8 expression. Two signaling mechanisms are involved in the GPx1-dependent regulation of the apoptosis pathway: (1) GPx1 regulates the level of cytosolic H2O2 that oxidizes the redox protein thioredoxin 1, blocking ASK1 activation, and (2) GPx1 interacts with TRAF2 and interferes with the formation of the active ASK1 complex. Inducible knockdown of GPx1 expression impaired the tumorigenic growth of MDA-MB-231 cells (>70% reduction, P = 0.0034) implanted in mice by promoting apoptosis in vivo. Overall, this study reveals the apoptosis-related signaling function of a GPx family enzyme highly conserved in aerobic organisms.

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iPLA2β Contributes to ER Stress-Induced Apoptosis during Myocardial Ischemia/Reperfusion Injury

Cells ◽

10.3390/cells10061446 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1446

Author(s):

Tingting Jin ◽

Jun Lin ◽

Yingchao Gong ◽

Xukun Bi ◽

Shasha Hu ◽

...

Keyword(s):

Cell Death ◽

Heart Disease ◽

Myocardial Ischemia ◽

Ischemic Heart Disease ◽

Er Stress ◽

Ischemia Reperfusion ◽

Myocardial Ischemia Reperfusion ◽

Induced Apoptosis

Both calcium-independent phospholipase A2 beta (iPLA2β) and endoplasmic reticulum (ER) stress regulate important pathophysiological processes including inflammation, calcium homeostasis and apoptosis. However, their roles in ischemic heart disease are poorly understood. Here, we show that the expression of iPLA2β is increased during myocardial ischemia/reperfusion (I/R) injury, concomitant with the induction of ER stress and the upregulation of cell death. We further show that the levels of iPLA2β in serum collected from acute myocardial infarction (AMI) patients and in samples collected from both in vivo and in vitro I/R injury models are significantly elevated. Further, iPLA2β knockout mice and siRNA mediated iPLA2β knockdown are employed to evaluate the ER stress and cell apoptosis during I/R injury. Additionally, cell surface protein biotinylation and immunofluorescence assays are used to trace and locate iPLA2β. Our data demonstrate the increase of iPLA2β augments ER stress and enhances cardiomyocyte apoptosis during I/R injury in vitro and in vivo. Inhibition of iPLA2β ameliorates ER stress and decreases cell death. Mechanistically, iPLA2β promotes ER stress and apoptosis by translocating to ER upon myocardial I/R injury. Together, our study suggests iPLA2β contributes to ER stress-induced apoptosis during myocardial I/R injury, which may serve as a potential therapeutic target against ischemic heart disease.

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Characterization of Endoplasmic Reticulum (ER) in Human Pluripotent Stem Cells Revealed Increased Susceptibility to Cell Death upon ER Stress

Cells ◽

10.3390/cells9051078 ◽

2020 ◽

Vol 9 (5) ◽

pp. 1078

Author(s):

Tae Won Ha ◽

Ji Hun Jeong ◽

HyeonSeok Shin ◽

Hyun Kyu Kim ◽

Jeong Suk Im ◽

...

Keyword(s):

Stem Cells ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Pluripotent Stem Cells ◽

Meta Analysis ◽

Embryonic Stem ◽

Structural Features ◽

Human Pluripotent Stem Cells ◽

Differentiated Cells ◽

Induced Apoptosis

Human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have a well-orchestrated program for differentiation and self-renewal. However, the structural features of unique proteostatic-maintaining mechanisms in hPSCs and their features, distinct from those of differentiated cells, in response to cellular stress remain unclear. We evaluated and compared the morphological features and stress response of hPSCs and fibroblasts. Compared to fibroblasts, electron microscopy showed simpler/fewer structures with fewer networks in the endoplasmic reticulum (ER) of hPSCs, as well as lower expression of ER-related genes according to meta-analysis. As hPSCs contain low levels of binding immunoglobulin protein (BiP), an ER chaperone, thapsigargin treatment sharply increased the gene expression of the unfolded protein response. Thus, hPSCs with decreased chaperone function reacted sensitively to ER stress and entered apoptosis faster than fibroblasts. Such ER stress-induced apoptotic processes were abolished by tauroursodeoxycholic acid, an ER-stress reliever. Hence, our results revealed that as PSCs have an underdeveloped structure and express fewer BiP chaperone proteins than somatic cells, they are more susceptible to ER stress-induced apoptosis in response to stress.

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Metabolomic Profiling Reveals a Role for Caspase-2 in Lipoapoptosis

Journal of Biological Chemistry ◽

10.1074/jbc.m112.437210 ◽

2013 ◽

Vol 288 (20) ◽

pp. 14463-14475 ◽

Cited By ~ 29

Author(s):

Erika Segear Johnson ◽

Kelly R. Lindblom ◽

Alexander Robeson ◽

Robert D. Stevens ◽

Olga R. Ilkayeva ◽

...

Keyword(s):

Mammalian Cells ◽

Metabolic Diseases ◽

Response To Treatment ◽

Alcoholic Fatty Liver ◽

Metabolomic Profiling ◽

Egg Extracts ◽

Attractive Therapeutic Target ◽

Caspase 2 ◽

Induced Apoptosis ◽

Alcoholic Fatty Liver Disease

The accumulation of long-chain fatty acids (LCFAs) in non-adipose tissues results in lipid-induced cytotoxicity (or lipoapoptosis). Lipoapoptosis has been proposed to play an important role in the pathogenesis of several metabolic diseases, including non-alcoholic fatty liver disease, diabetes mellitus, and cardiovascular disease. In this report, we demonstrate a novel role for caspase-2 as an initiator of lipoapoptosis. Using a metabolomics approach, we discovered that the activation of caspase-2, the initiator of apoptosis in Xenopus egg extracts, is associated with an accumulation of LCFA metabolites. Metabolic treatments that blocked the buildup of LCFAs potently inhibited caspase-2 activation, whereas adding back an LCFA in this scenario restored caspase activation. Extending these findings to mammalian cells, we show that caspase-2 was engaged and activated in response to treatment with the saturated LCFA palmitate. Down-regulation of caspase-2 significantly impaired cell death induced by saturated LCFAs, suggesting that caspase-2 plays a pivotal role in lipid-induced cytotoxicity. Together, these findings reveal a previously unknown role for caspase-2 as an initiator caspase in lipoapoptosis and suggest that caspase-2 may be an attractive therapeutic target for inhibiting pathological lipid-induced apoptosis.

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