Saturated fatty acids induce endoplasmic reticulum stress and apoptosis independently of ceramide in liver cells

2006 ◽  
Vol 291 (2) ◽  
pp. E275-E281 ◽  
Author(s):  
Yuren Wei ◽  
Dong Wang ◽  
Farran Topczewski ◽  
Michael J. Pagliassotti
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Liver Cells ◽  
Caspase Activity ◽  
Dna Laddering ◽  
Er Homeostasis

Accumulation of lipids in nonadipose tissues can lead to cell dysfunction and cell death, a phenomenon known as lipotoxicity. However, the signaling pathways and mechanisms linking lipid accumulation to cell death are poorly understood. The present study examined the hypothesis that saturated fatty acids disrupt endoplasmic reticulum (ER) homeostasis and promote apoptosis in liver cells via accumulation of ceramide. H4IIE liver cells were exposed to varying concentrations of saturated (palmitate or stearate) or unsaturated (oleate or linoleate) fatty acids. ER homeostasis was monitored using markers of the ER stress response pathway, including phosphorylation of IRE1α and eIF2α, splicing of XBP1 mRNA, and expression of molecular chaperone (e.g., GRP78) and proapoptotic (CCAAT/enhancer-binding protein homologous protein) genes. Apoptosis was monitored using caspase activity and DNA laddering. Palmitate and stearate induced ER stress, caspase activity, and DNA laddering. Inhibition of caspase activation prevented DNA laddering. Unsaturated fatty acids did not induce ER stress or apoptosis. Saturated fatty acids increased ceramide concentration; however, inhibition of de novo ceramide synthesis did not prevent saturated fatty acid-induced ER stress and apoptosis. Unsaturated fatty acids rescued palmitate-induced ER stress and apoptosis. These data demonstrate that saturated fatty acids disrupt ER homeostasis and induce apoptosis in liver cells via mechanisms that do not involve ceramide accumulation.

scholarly journals Docosahexaenoic and Eicosapentaenoic Acids Prevent Altered-Muc2 Secretion Induced by Palmitic Acid by Alleviating Endoplasmic Reticulum Stress in LS174T Goblet Cells

Nutrients ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 2179
Author(s):  
Quentin Escoula ◽  
Sandrine Bellenger ◽  
Michel Narce ◽  
Jérôme Bellenger
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Palmitic Acid ◽  
Er Stress ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Goblet Cells ◽  
The Impact

Diets high in saturated fatty acids (FA) represent a risk factor for the development of obesity and associated metabolic disorders, partly through their impact on the epithelial cell barrier integrity. We hypothesized that unsaturated FA could alleviate saturated FA-induced endoplasmic reticulum (ER) stress occurring in intestinal secretory goblet cells, and consequently the reduced synthesis and secretion of mucins that form the protective mucus barrier. To investigate this hypothesis, we treated well-differentiated human colonic LS174T goblet cells with palmitic acid (PAL)—the most commonly used inducer of lipotoxicity in in vitro systems—or n-9, n-6, or n-3 unsaturated fatty acids alone or in co-treatment with PAL, and measured the impact of such treatments on ER stress and Muc2 production. Our results showed that only eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids protect goblet cells against ER stress-mediated altered Muc2 secretion induced by PAL, whereas neither linolenic acid nor n-9 and n-6 FA are able to provide such protection. We conclude that EPA and DHA could represent potential therapeutic nutrients against the detrimental lipotoxicity of saturated fatty acids, associated with type 2 diabetes and obesity or inflammatory bowel disease. These in vitro data remain to be explored in vivo in a context of dietary obesity.

scholarly journals Linking endoplasmic reticulum stress to cell death in hepatocytes: roles of C/EBP homologous protein and chemical chaperones in palmitate-mediated cell death

2010 ◽  
Vol 298 (5) ◽  
pp. E1027-E1035 ◽  
Author(s):  
Kyle T. Pfaffenbach ◽  
Christopher L. Gentile ◽  
Angela M. Nivala ◽  
Dong Wang ◽  
Yuren Wei ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Liver Cells ◽  
Primary Hepatocytes ◽  
Deficient Diet ◽  
Chemical Chaperones ◽  
Homologous Protein ◽  
Jnk Activation

Prolonged endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) have been linked to apoptosis via several mechanisms, including increased expression of C/EBP homologous protein ( Chop). Increased long-chain fatty acids, in particular saturated fatty acids, induce ER stress, Chop expression, and apoptosis in liver cells. The first aim of the present study was to determine the role of Chop in lipid-induced hepatocyte cell death and liver injury induced by a methionine-choline-deficient diet. Albumin-bound palmitate increased Chop gene and protein expression in a dose-dependent fashion in H4IIE liver cells. siRNA-mediated silencing of Chop in H4IIE liver cells reduced thapsigargin-mediated cell death by ∼40% and delayed palmitate-mediated cell death, but only at high concentrations of palmitate (400–500 μM). Similar results were observed in primary hepatocytes isolated from Chop-knockout mice. Indices of liver injury were also not reduced in Chop-knockout mice provided a methionine-choline-deficient diet. To ascertain whether ER stress was linked to palmitate-induced cell death, primary hepatocytes were incubated in the absence or presence of the chemical chaperones taurine-conjugated ursodeoxycholic acid or 4-phenylbutyric acid. The presence of either of these chemical chaperones protected liver cells from palmitate-mediated ER stress and cell death, in part, via inhibition of JNK activation. These data suggest that ER stress is linked to palmitate-mediated cell death via mechanisms that include JNK activation.

scholarly journals Saturated fatty acids activate caspase-4/5 in human monocytes, triggering IL-1β and IL-18 release

2016 ◽  
Vol 311 (5) ◽  
pp. E825-E835 ◽  
Author(s):  
Nicolas J. Pillon ◽  
Kenny L. Chan ◽  
Shitian Zhang ◽  
Marios Mejdani ◽  
Maya R. Jacobson ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Cell Death ◽  
Unsaturated Fatty Acids ◽  
Human Peripheral Blood ◽  
Saturated Fatty Acids ◽  
Caspase Activity ◽  
Human Monocytes ◽  
Blood Monocytes ◽  
Cell Death Program ◽  
Proinflammatory Gene

Obesity is associated with metabolic tissue infiltration by monocyte-derived macrophages. Saturated fatty acids contribute to proinflammatory gene induction in tissue-embedded immune cells. However, it is unknown how circulating monocytes, the macrophage precursors, react to high-fat environments. In macrophages, saturated fatty acids activate inflammatory pathways and, notably, prime caspase-associated inflammasomes. Inflammasome-activated IL-1β contributes to type 2 diabetes. We hypothesized that 1) human monocytes from obese patients show caspase activation, and 2) fatty acids trigger this response and consequent release of IL-1β/IL-18. Human peripheral blood monocytes were sorted by flow cytometry, and caspase activity was measured with a FLICA dye-based assay. Blood monocytes from obese individuals exhibited elevated caspase activity. To explore the nature and consequence of this activity, human THP1 monocytes were exposed to saturated or unsaturated fatty acids. Caspase activity was revealed by isoform-specific cleavage and enzymatic activity; cytokine expression/release was measured by qPCR and ELISA. Palmitate, but not palmitoleate, increased caspase activity in parallel to the release of IL-1β and IL-18. Palmitate induced eventual monocyte cell death with features of pyroptosis (an inflammation-linked cell death program involving caspase-4/5), scored through LDH release, vital dye influx, cell volume changes, and nuclear morphology. Notably, selective gene silencing or inhibition of caspase-4/5 reduced palmitate-induced release of IL-1β and IL-18. In summary, monocytes from obese individuals present elevated caspase activity. Mechanistically, palmitate activates a pyroptotic program in monocytes through caspase-4/5, causing inflammatory cytokine release, additional to inflammasomes. These caspases represent potential, novel, therapeutic targets to taper obesity-associated inflammation.

scholarly journals Saturated fatty acids induce endoplasmic reticulum stress in primary cardiomyocytes

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Taha Haffar ◽  
Félix-Antoine Bérubé-Simard ◽  
Jean-Claude Tardif ◽  
Nicolas Bousette
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Lipid Accumulation ◽  
Apoptotic Cell ◽  
Saturated Fatty Acids ◽  
Fatty Acid Uptake ◽  
Apoptotic Cell Death ◽  
Acid Uptake

AbstractAbstract: Introduction: Diabetes is a major contributor to cardiovascular disease. There is a growing body of evidence pointing towards intra-myocellular lipid accumulation as an integral etiological factor. Here we aimed to determine the effect of two common fatty acids on lipid accumulation and cellular stress in primary cardiomyocytes.Methods: We evaluated lipid accumulation biochemically (by triacylglyceride assay and radiolabeled fatty acid uptake assay) as well as histologically (by BODIPY 493/503 staining) in mouse and rat neonatal cardiomyocytes treated with saturated (palmitate) or mono-unsaturated (oleate) fatty acids. Endoplasmic reticulum (ER) stress was evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting. Cell viability was assessed by propidium iodide staining.Results: We found that both oleate and palmitate led to significant increases in intracellular lipid in cardiomyocytes; however there were distinct differences in the qualitative nature of BODIPY staining between oleate and palmitate treated cardiomyocytes. We also show that palmitate caused significant apoptotic cell death and this was associated with ER stress. Interestingly, co-administration of oleate with palmitate abolished cell death, and ER stress. Finally, palmitate treatment caused a significant increase in ubiquitination of Grp78, a key compensatory ER chaperone.Conclusion: Palmitate causes ER stress and apoptotic cell death in primary cardiomyocytes and this is associated with apparent differences in BODIPY staining compared to oleate treated cardiomyocytes. Importantly, the lipotoxic effects of palmitate are abolished with the co-administration of oleate.

scholarly journals Saturated Fatty Acids Promote GDF15 Expression in Human Macrophages through the PERK/eIF2/CHOP Signaling Pathway

Nutrients ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3771
Author(s):  
Laurent L’homme ◽  
Benan Pelin Sermikli ◽  
Bart Staels ◽  
Jacques Piette ◽  
Sylvie Legrand-Poels ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Fatty Acids ◽  
Er Stress ◽  
Signaling Pathway ◽  
Promoter Region ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Growth Differentiation Factor 15 ◽  
Human Macrophages ◽  
Primary Monocyte

Growth differentiation factor-15 (GDF-15) and its receptor GFRAL are both involved in the development of obesity and insulin resistance. Plasmatic GDF-15 level increases with obesity and is positively associated with disease progression. Despite macrophages have been recently suggested as a key source of GDF-15 in obesity, little is known about the regulation of GDF-15 in these cells. In the present work, we sought for potential pathophysiological activators of GDF15 expression in human macrophages and identified saturated fatty acids (SFAs) as strong inducers of GDF15 expression and secretion. SFAs increase GDF15 expression through the induction of an ER stress and the activation of the PERK/eIF2/CHOP signaling pathway in both PMA-differentiated THP-1 cells and in primary monocyte-derived macrophages. The transcription factor CHOP directly binds to the GDF15 promoter region and regulates GDF15 expression. Unlike SFAs, unsaturated fatty acids do not promote GDF15 expression and rather inhibit both SFA-induced GDF15 expression and ER stress. These results suggest that free fatty acids may be involved in the control of GDF-15 and provide new molecular insights about how diet and lipid metabolism may regulate the development of obesity and T2D.

scholarly journals Destabilization of β-cell FIT2 by saturated fatty acids contribute to ER stress and diabetes

2021 ◽  
Author(s):  
Xiaofeng Zheng ◽  
Qing Wei Calvin Ho ◽  
Minni Chua ◽  
Olga Stelmashenko ◽  
Sneha Muralidharan ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Er Stress ◽  
Unsaturated Fatty Acids ◽  
Transmembrane Protein ◽  
Saturated Fatty Acids ◽  
Protective Role ◽  
Sequencing Analysis ◽  
Β Cell ◽  
Obesity And Diabetes ◽  
Ceramide Synthases

ABSTRACTWestern type diets are linked to obesity and diabetes partly because of their high saturated fatty acid (SFA) content. We found that SFAs, but not unsaturated fatty acids (USFAs), reduced the number of lipid droplets (LDs) within pancreatic β-cells. Mechanistically, SFAs but not USFAs disabled LD biogenesis by inducing palmitoylation and subsequent ERAD-C mediated degradation of LD formation protein, Fat storage-Inducing Transmembrane protein 2 (FIT2). Targeted ablation of FIT2 reduced β-cell LD numbers, lowered β-cell ATP levels, reduced Ca2+ signaling, downregulated β-cell transcription factors (RNA sequencing analysis), and exacerbated diet-induced diabetes in mice. Subsequent mass spectrometry studies revealed increased C16:0 ceramide accumulation in islets of mice lacking β-cell FIT2 under lipotoxic conditions. Inhibition of ceramide synthases ameliorated the enhanced ER stress. Overexpression of FIT2 increased number of intracellular LDs and rescued SFA-induced ER-stress and apoptosis thereby highlighting the protective role of FIT2 and LDs against β-cell lipotoxicity and diet-induced diabetes.

scholarly journals Mechanisms of Action of trans Fatty Acids

2019 ◽  
Vol 11 (3) ◽  
pp. 697-708 ◽  
Author(s):  
Antwi-Boasiako Oteng ◽  
Sander Kersten
Keyword(s):  
Fatty Acids ◽  
Er Stress ◽  
Trans Fatty Acids ◽  
Cholesterol Synthesis ◽  
Molecular Mechanisms ◽  
Unsaturated Fatty Acids ◽  
Regulatory Element ◽  
Saturated Fatty Acids ◽  
Mechanisms Of Action ◽  
Plasma Lipoproteins

ABSTRACT Human studies have established a positive association between the intake of industrial trans fatty acids and the development of cardiovascular diseases, leading several countries to enact laws that restrict the presence of industrial trans fatty acids in food products. However, trans fatty acids cannot be completely eliminated from the human diet since they are also naturally present in meat and dairy products of ruminant animals. Moreover, bans on industrial trans fatty acids have not yet been instituted in all countries. The epidemiological evidence against trans fatty acids by far overshadows mechanistic insights that may explain how trans fatty acids achieve their damaging effects. This review focuses on the mechanisms that underlie the deleterious effects of trans fatty acids by juxtaposing effects of trans fatty acids against those of cis-unsaturated fatty acids and saturated fatty acids (SFAs). This review also carefully explores the argument that ruminant trans fatty acids have differential effects from industrial trans fatty acids. Overall, in vivo and in vitro studies demonstrate that industrial trans fatty acids promote inflammation and endoplasmic reticulum (ER) stress, although to a lesser degree than SFAs, whereas cis-unsaturated fatty acids are protective against ER stress and inflammation. Additionally, industrial trans fatty acids promote fat storage in the liver at the expense of adipose tissue compared with cis-unsaturated fatty acids and SFAs. In cultured hepatocytes and adipocytes, industrial trans fatty acids, but not cis-unsaturated fatty acids or SFAs, stimulate the cholesterol synthesis pathway by activating sterol regulatory element binding protein (SREBP) 2–mediated gene regulation. Interestingly, although industrial and ruminant trans fatty acids show similar effects on human plasma lipoproteins, in preclinical models, only industrial trans fatty acids promote inflammation, ER stress, and cholesterol synthesis. Overall, clearer insight into the molecular mechanisms of action of trans fatty acids may create new therapeutic windows for the treatment of diseases characterized by disrupted lipid metabolism.

scholarly journals Regulation of podocyte survival and endoplasmic reticulum stress by fatty acids

2010 ◽  
Vol 299 (4) ◽  
pp. F821-F829 ◽  
Author(s):  
Jonas Sieber ◽  
Maja Tamara Lindenmeyer ◽  
Kapil Kampe ◽  
Kirk Nicholas Campbell ◽  
Clemens David Cohen ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Oleic Acid ◽  
Palmitic Acid ◽  
Er Stress ◽  
Unfolded Protein ◽  
Homologous Protein ◽  
Protein Response ◽  
Apoptosis And Necrosis

Apoptosis of podocytes is considered critical in the pathogenesis of diabetic nephropathy (DN). Free fatty acids (FFAs) are critically involved in the pathogenesis of diabetes mellitus type 2, in particular the regulation of pancreatic β cell survival. The objectives of this study were to elucidate the role of palmitic acid, palmitoleic, and oleic acid in the regulation of podocyte cell death and endoplasmic reticulum (ER) stress. We show that palmitic acid increases podocyte cell death, both apoptosis and necrosis of podocytes, in a dose and time-dependent fashion. Palmitic acid induces podocyte ER stress, leading to an unfolded protein response as reflected by the induction of the ER chaperone immunoglobulin heavy chain binding protein (BiP) and proapoptotic C/EBP homologous protein (CHOP) transcription factor. Of note, the monounsaturated palmitoleic and oleic acid can attenuate the palmitic acid-induced upregulation of CHOP, thereby preventing cell death. Similarly, gene silencing of CHOP protects against palmitic acid-induced podocyte apoptosis. Our results offer a rationale for interventional studies aimed at testing whether dietary shifting of the FFA balance toward unsaturated FFAs can delay the progression of DN.

scholarly journals Identification of differentially expressed microRNAs during lipotoxic endoplasmic reticulum stress in RAW264.7 macrophages / RAW264.7 makrofajlarında lipotoksik endoplazmik retikulum stres sürecinde ifadesi değişen mikroRNAların tanımlanması

2016 ◽  
Vol 41 (3) ◽  
Author(s):  
Mısra Nadir ◽  
Özlem Tufanlı ◽  
Ebru Erbay ◽  
Arzu Atalay
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Cell Line ◽  
Pathway Analysis ◽  
Dynamic Range ◽  
Saturated Fatty Acids ◽  
Mirna Biogenesis ◽  
Altered Expression ◽  
Raw264.7 Macrophages

AbstractObjective: Increased fatty acids in the circulation and their accumulation in non-adipose tissues play a significant role in the development of obesity related metabolic and inflammatory disorders such as insulin resistance, diabetes and atherosclerosis. While fat tissue has the ability to store excess fatty acids, uptake of excess fatty acids to other tissues burdens intracellular metabolic organelles such as mitochondria and endoplasmic reticulum (ER), leading to stress response and lipotoxic cell death. Unfolded protein response (UPR) is a key adaptation of the ER to stress. It is still not completely clear how lipids engage the UPR and how UPR manages both the adaptive and destructive consequences under its control. Increasing evidence point to the importance of miRNA regulation of the UPR as well as UPR’s role in miRNA biogenesis. In order to understand how lipids engage the UPR, we set forth to identify microRNAs regulated by lipotoxic ER stress in macrophages.Methods: We stressed the mouse macrophage cell line (RAW 264.7) with a saturated fatty acid, 500μM palmitate, reflecting the levels found in the circulation of obese patients. We analyzed the microRNAome profiles of this cell line using QRT-PCR based miScript miRNA PCR array which contained all known mouse microRNAs in miRBase release16 and performed pathway analysis for potential targets.Results: 227 microRNAs showed altered expression levels; 43 microRNAs above 2 fold difference and 13 microRNAs 3-24 fold difference. Pathway analysis enriched the target mRNAs of these lipotoxic ER stress associated miRNAs.Conclusion: When exposed to high concentrations of saturated fatty acids that can induce ER stress, macrophages display a dynamic range of changes in their microRNAome profiles. Our findings reflect the consequences of lipotoxic stress on circulating monocytes and tissue-associated macrophages in obesity. Further studies are needed to deliniate which UPR arm is reponsible for the microRNA changes reported here.

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