Palmitate and oleate exert differential effects on insulin signalling and glucose uptake in human skeletal muscle cells

Saturated fatty acids are implicated in the development of insulin resistance, whereas unsaturated fatty acids may have a protective effect on metabolism. We tested in primary human myotubes if insulin resistance induced by saturated fatty acid palmitate can be ameliorated by concomitant exposure to unsaturated fatty acid oleate. Primary human myotubes were pretreated with palmitate, oleate or their combination for 12 h. Glucose uptake was determined by intracellular accumulation of [3H]-2-deoxy-d-glucose, insulin signalling and activation of endoplasmic reticulum (ER) stress by Western blotting, and mitochondrial reactive oxygen species (ROS) production by fluorescent dye MitoSOX. Exposure of primary human myotubes to palmitate impaired insulin-stimulated Akt-Ser473, AS160 and GSK-3β phosphorylation, induced ER stress signalling target PERK and stress kinase JNK 54 kDa isoform. These effects were virtually abolished by concomitant exposure of palmitate-treated myotubes to oleate. However, an exposure to palmitate, oleate or their combination reduced insulin-stimulated glucose uptake. This was associated with increased mitochondrial ROS production in palmitate-treated myotubes co-incubated with oleate, and was alleviated by antioxidants MitoTempo and Tempol. Thus, metabolic and intracellular signalling events diverge in myotubes treated with palmitate and oleate. Exposure of human myotubes to excess fatty acids increases ROS production and induces insulin resistance.

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CD36 inhibition prevents lipid accumulation and contractile dysfunction in rat cardiomyocytes

Biochemical Journal ◽

10.1042/bj20120060 ◽

2012 ◽

Vol 448 (1) ◽

pp. 43-53 ◽

Cited By ~ 50

Author(s):

Yeliz Angin ◽

Laura K. M. Steinbusch ◽

Peter J. Simons ◽

Sabrina Greulich ◽

Nicole T. H. Hoebers ◽

...

Keyword(s):

Insulin Resistance ◽

Fatty Acid ◽

Glucose Uptake ◽

Lipid Accumulation ◽

Insulin Signalling ◽

Culture Conditions ◽

Contractile Dysfunction ◽

Rat Cardiomyocytes ◽

Akt Phosphorylation ◽

Palmitate Uptake

An increased cardiac fatty acid supply and increased sarcolemmal presence of the long-chain fatty acid transporter CD36 are associated with and contribute to impaired cardiac insulin sensitivity and function. In the present study we aimed at preventing the development of insulin resistance and contractile dysfunction in cardiomyocytes by blocking CD36-mediated palmitate uptake. Insulin resistance and contractile dysfunction were induced in primary cardiomyocytes by 48 h incubation in media containing either 100 nM insulin (high insulin; HI) or 200 μM palmitate (high palmitate; HP). Under both culture conditions, insulin-stimulated glucose uptake and Akt phosphorylation were abrogated or markedly reduced. Furthermore, cardiomyocytes cultured in each medium displayed elevated sarcolemmal CD36 content, increased basal palmitate uptake, lipid accumulation and decreased sarcomere shortening. Immunochemical CD36 inhibition enhanced basal glucose uptake and prevented elevated basal palmitate uptake, triacylglycerol accumulation and contractile dysfunction in cardiomyocytes cultured in either medium. Additionally, CD36 inhibition prevented loss of insulin signalling in cells cultured in HP, but not in HI medium. In conclusion, CD36 inhibition prevents lipid accumulation and lipid-induced contractile dysfunction in cardiomyocytes, but probably independently of effects on insulin signalling. Nonetheless, pharmacological CD36 inhibition may be considered as a treatment strategy to counteract impaired functioning of the lipid-loaded heart.

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Characterising hyperinsulinemia-induced insulin resistance in human skeletal muscle cells

Journal of Molecular Endocrinology ◽

10.1530/jme-19-0169 ◽

2020 ◽

Vol 64 (3) ◽

pp. 125-132 ◽

Cited By ~ 2

Author(s):

Mark C Turner ◽

Neil R W Martin ◽

Darren J Player ◽

Richard A Ferguson ◽

Patrick Wheeler ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Glucose Uptake ◽

Human Skeletal Muscle ◽

Glucose Transporter ◽

Insulin Signalling ◽

Insulin Stimulation ◽

Healthy Human ◽

Glucose Transporter 1 ◽

Human Skeletal Muscle Cells

Hyperinsulinaemia potentially contributes to insulin resistance in metabolic tissues, such as skeletal muscle. The purpose of these experiments was to characterise glucose uptake, insulin signalling and relevant gene expression in primary human skeletal muscle-derived cells (HMDCs), in response to prolonged insulin exposure (PIE) as a model of hyperinsulinaemia-induced insulin resistance. Differentiated HMDCs from healthy human donors were cultured with or without insulin (100 nM) for 3 days followed by an acute insulin stimulation. HMDCs exposed to PIE were characterised by impaired insulin-stimulated glucose uptake, blunted IRS-1 phosphorylation (Tyr612) and Akt (Ser473) phosphorylation in response to an acute insulin stimulation. Glucose transporter 1 (GLUT1), but not GLUT4, mRNA and protein increased following PIE. The mRNA expression of metabolic (PDK4) and inflammatory markers (TNF-α) was reduced by PIE but did not change lipid (SREBP1 and CD36) or mitochondrial (UCP3) markers. These experiments provide further characterisation of the effects of PIE as a model of hyperinsulinaemia-induced insulin resistance in HMDCs.

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Circulating fatty acid profiles are associated with protein energy wasting in maintenance hemodialysis patients: a cross-sectional study

Scientific Reports ◽

10.1038/s41598-020-80812-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ban-Hock Khor ◽

◽

Sharmela Sahathevan ◽

Ayesha Sualeheen ◽

Mohammad Syafiq Md Ali ◽

...

Keyword(s):

Insulin Resistance ◽

Fatty Acids ◽

Fatty Acid ◽

Nutritional Status ◽

Serum Albumin ◽

Saturated Fatty Acids ◽

Maintenance Hemodialysis ◽

Model Assessment ◽

Cross Sectional ◽

Markers Of Inflammation

AbstractThe metabolic impact of circulating fatty acids (FAs) in patients requiring hemodialysis (HD) is unknown. We investigated the associations between plasma triglyceride (TG) FAs and markers of inflammation, insulin resistance, nutritional status and body composition. Plasma TG-FAs were measured using gas chromatography in 341 patients on HD (age = 55.2 ± 14.0 years and 54.3% males). Cross-sectional associations of TG-FAs with 13 markers were examined using multivariate linear regression adjusted for potential confounders. Higher levels of TG saturated fatty acids were associated with greater body mass index (BMI, r = 0.230), waist circumference (r = 0.203), triceps skinfold (r = 0.197), fat tissue index (r = 0.150), serum insulin (r = 0.280), and homeostatic model assessment of insulin resistance (r = 0.276), but lower malnutrition inflammation score (MIS, r = − 0.160). Greater TG monounsaturated fatty acid levels were associated with lower lean tissue index (r = − 0.197) and serum albumin (r = − 0.188), but higher MIS (r = 0.176). Higher levels of TG n-3 polyunsaturated fatty acids (PUFAs) were associated with lower MIS (r = − 0.168) and interleukin-6 concentrations (r = − 0.115). Higher levels of TG n-6 PUFAs were associated with lower BMI (r = − 0.149) but greater serum albumin (r = 0.112). In conclusion, TG monounsaturated fatty acids were associated with poor nutritional status, while TG n-3 PUFAs were associated with good nutritional status. On the other hand, TG saturated fatty acids and TG n-6 PUFAs had both favorable and unfavorable associations with nutritional parameters.

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Insulin-independent regulation of hepatic triglyceride synthesis by fatty acids

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1423952112 ◽

2015 ◽

Vol 112 (4) ◽

pp. 1143-1148 ◽

Cited By ~ 118

Author(s):

Daniel F. Vatner ◽

Sachin K. Majumdar ◽

Naoki Kumashiro ◽

Max C. Petersen ◽

Yasmeen Rahimi ◽

...

Keyword(s):

Insulin Resistance ◽

Fatty Acids ◽

Fatty Acid ◽

Insulin Signaling ◽

Plasma Fatty Acid ◽

Hepatic Triglyceride ◽

Triglyceride Synthesis ◽

Hepatic Glucose ◽

Acid Esterification ◽

Fatty Acid Esterification

A central paradox in type 2 diabetes is the apparent selective nature of hepatic insulin resistance—wherein insulin fails to suppress hepatic glucose production yet continues to stimulate lipogenesis, resulting in hyperglycemia, hyperlipidemia, and hepatic steatosis. Although efforts to explain this have focused on finding a branch point in insulin signaling where hepatic glucose and lipid metabolism diverge, we hypothesized that hepatic triglyceride synthesis could be driven by substrate, independent of changes in hepatic insulin signaling. We tested this hypothesis in rats by infusing [U-13C] palmitate to measure rates of fatty acid esterification into hepatic triglyceride while varying plasma fatty acid and insulin concentrations independently. These experiments were performed in normal rats, high fat-fed insulin-resistant rats, and insulin receptor 2′-O-methoxyethyl chimeric antisense oligonucleotide-treated rats. Rates of fatty acid esterification into hepatic triglyceride were found to be dependent on plasma fatty acid infusion rates, independent of changes in plasma insulin concentrations and independent of hepatocellular insulin signaling. Taken together, these results obviate a paradox of selective insulin resistance, because the major source of hepatic lipid synthesis, esterification of preformed fatty acids, is primarily dependent on substrate delivery and largely independent of hepatic insulin action.

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MicroRNA-27b-3p regulates function and metabolism in insulin resistance cells by inhibiting receptor tyrosine kinase-like orphan receptor 1

European Journal of Inflammation ◽

10.1177/2058739218762058 ◽

2018 ◽

Vol 16 ◽

pp. 205873921876205

Author(s):

Yong Liu ◽

Guohui Wang ◽

Xiangwu Yang ◽

Pengzhou Li ◽

Hao Ling ◽

...

Keyword(s):

Insulin Resistance ◽

Fatty Acid ◽

Tyrosine Kinase ◽

Glucose Uptake ◽

Fatty Acid Oxidation ◽

Receptor Tyrosine Kinase ◽

Cell Model ◽

Orphan Receptor ◽

Acid Oxidation ◽

Metabolism Disorder

Type 2 diabetes mellitus (T2DM) is associated with insulin resistance-induced lipid and glucose metabolism disorder. The study was aimed to explore the potential functional role of microRNA (miR)-27b-3p in T2DM, as well as underlying mechanisms. An insulin resistance cell model was induced in HepG2 cells and then expression of miR-27b-3p and receptor tyrosine kinase-like orphan receptor 1 (ROR1) was analyzed. The expression of miR-27b-3p was overexpressed or silenced, and the relationship between ROR1 and miR-27b-3p was investigated. Thereafter, the effects of miR-27b-3p on percentage of glucose uptake, fatty acid oxidation and cell cycle were analyzed. The expressions of miR-27b-3p were significantly increased, while the ROR1 levels were statistically decreased in the cells of the model group. Overexpression of miR-27b-3p dramatically decreased the levels of ROR1 and the percentage of glucose uptake, but had no effects on fatty acid oxidation. ROR1 was a target of miR-27b-3p. Moreover, overexpression of miR-27b-3p could remarkably highlight the percentages of cells at G0/G1 phase, but decreased the percentages of cells at S phase. In conclusion, our results suggest that miR-27b-3p regulates the function and metabolism of insulin resistance cells by inhibiting ROR1. miR-27b-3p might be a potential drug target in treating T2DM.

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

Nutrients ◽

10.3390/nu12123771 ◽

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.

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GH replacement causing acute hyperglycaemia and ketonuria in a type 1 diabetic patient

Endocrinology Diabetes and Metabolism Case Reports ◽

10.1530/edm-13-0047 ◽

2013 ◽

Vol 2013 ◽

Cited By ~ 1

Author(s):

Dominic Cavlan ◽

Shanti Vijayaraghavan ◽

Susan Gelding ◽

William Drake

Keyword(s):

Insulin Resistance ◽

Fatty Acids ◽

Type 1 Diabetes ◽

Fatty Acid ◽

Diabetic Patient ◽

Acid Cycle ◽

Gh Replacement ◽

Glucose Fatty Acid Cycle ◽

Gh Excess

Summary A state of insulin resistance is common to the clinical conditions of both chronic growth hormone (GH) deficiency and GH excess (acromegaly). GH has a physiological role in glucose metabolism in the acute settings of fast and exercise and is the only anabolic hormone secreted in the fasting state. We report the case of a patient in whom knowledge of this aspect of GH physiology was vital to her care. A woman with well-controlled type 1 diabetes mellitus who developed hypopituitarism following the birth of her first child required GH replacement therapy. Hours after the first dose, she developed a rapid metabolic deterioration and awoke with hyperglycaemia and ketonuria. She adjusted her insulin dose accordingly, but the pattern was repeated with each subsequent increase in her dose. Acute GH-induced lipolysis results in an abundance of free fatty acids (FFA); these directly inhibit glucose uptake into muscle, and this can lead to hyperglycaemia. This glucose–fatty acid cycle was first described by Randle et al. in 1963; it is a nutrient-mediated fine control that allows oxidative muscle to switch between glucose and fatty acids as fuel, depending on their availability. We describe the mechanism in detail. Learning points There is a complex interplay between GH and insulin resistance: chronically, both GH excess and deficiency lead to insulin resistance, but there is also an acute mechanism that is less well appreciated by clinicians. GH activates hormone-sensitive lipase to release FFA into the circulation; these may inhibit the uptake of glucose leading to hyperglycaemia and ketosis in the type 1 diabetic patient. The Randle cycle, or glucose–fatty acid cycle, outlines the mechanism for this acute relationship. Monitoring the adequacy of GH replacement in patients with type 1 diabetes is difficult, with IGF1 an unreliable marker.

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Free Fatty acids receptors (FFAR2 and FFAR3) control cell proliferation by regulating cellular glucose uptake

10.21203/rs.2.12250/v1 ◽

2019 ◽

Author(s):

Mohammad Aziz ◽

Saeed Al Mahri ◽

Amal Alghamdi ◽

Maaged AlAkiel ◽

Monira Al Aujan ◽

...

Keyword(s):

Colorectal Cancer ◽

Fatty Acids ◽

Cell Proliferation ◽

Fatty Acid ◽

Free Fatty Acid ◽

Free Fatty Acids ◽

Glucose Uptake ◽

Microarray Data ◽

Free Fatty Acid Receptors

Abstract Background Colorectal cancer is a worldwide problem which has been associated with changes in diet and lifestyle pattern. As a result of colonic fermentation of dietary fibres, short chain free fatty acids are generated which activate Free Fatty Acid Receptors 2 and 3 (FFAR2 and FFAR3). FFAR2 and FFAR3 genes are abundantly expressed in colonic epithelium and play an important role in the metabolic homeostasis of colonic epithelial cells. Earlier studies point to the involvement of FFAR2 in colorectal carcinogenesis. Methods Transcriptome analysis console was used to analyse microarray data from patients and cell lines. We employed shRNA mediated down regulation of FFAR2 and FFAR3 genes which was assessed using qRT-PCR. Assays for glucose uptake and cAMP generation was done along with immunofluorescence studies. For measuring cell proliferation, we employed real time electrical impedance based assay available from xCelligence. Results Microarray data analysis of colorectal cancer patient samples showed a significant down regulation of FFAR2 gene expression. This prompted us to study the FFAR2 in colorectal cancer. Since, FFAR3 shares significant structural and functional homology with FFAR2, we knocked down both these receptors in colorectal cancer cell line HCT 116. These modified cell lines exhibited higher proliferation rate and were found to have increased glucose uptake as well as increased level of GLUT1. Since, FFAR2 and FFAR3 signal through G protein subunit (Gαi), knockdown of these receptors was associated with increased cAMP. Inhibition of PKA did not alter the growth and proliferation of these cells indicating a mechanism independent of cAMP/PKA pathway. Conclusion: Our results suggest role of FFAR2/FFAR3 genes in increased proliferation of colon cancer cells via enhanced glucose uptake and exclude the role of protein kinase A mediated cAMP signalling. Alternate pathways could be involved that would ultimately result in increased cell proliferation as a result of down regulated FFAR2/FFAR3 genes. This study paves the way to understand the mechanism of action of short chain free fatty acid receptors in colorectal cancer.

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Cultured hypothalamic neurons are resistant to inflammation and insulin resistance induced by saturated fatty acids

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00006.2010 ◽

2010 ◽

Vol 298 (6) ◽

pp. E1122-E1130 ◽

Cited By ~ 51

Author(s):

Sun Ju Choi ◽

Francis Kim ◽

Michael W. Schwartz ◽

Brent E. Wisse

Keyword(s):

Insulin Resistance ◽

Fatty Acids ◽

Fatty Acid ◽

Saturated Fatty Acid ◽

Cell Lines ◽

Saturated Fatty Acids ◽

Neuronal Cell ◽

Acid Exposure ◽

Inflammatory Signaling ◽

Hypothalamic Neurons

Hypothalamic inflammation induced by high-fat feeding causes insulin and leptin resistance and contributes to the pathogenesis of obesity. Since in vitro exposure to saturated fatty acids causes inflammation and insulin resistance in many cultured cell types, we determined how cultured hypothalamic neurons respond to this stimulus. Two murine hypothalamic neuronal cell cultures, N43/5 and GT1–7, were exposed to escalating concentrations of saturated fatty acids for up to 24 h. Harvested cells were evaluated for activation of inflammation by gene expression and protein content. Insulin-treated cells were evaluated for induction of markers of insulin receptor signaling (p-IRS, p-Akt). In both hypothalamic cell lines, inflammation was induced by prototypical inflammatory mediators LPS and TNFα, as judged by induction of IκBα (3- to 5-fold) and IL-6 (3- to 7-fold) mRNA and p-IκBα protein, and TNFα pretreatment reduced insulin-mediated p-Akt activation by 30% ( P < 0.05). By comparison, neither mixed saturated fatty acid (100, 250, or 500 μM for ≤6 h) nor palmitate exposure alone (200 μM for ≤24 h) caused inflammatory activation or insulin resistance in cultured hypothalamic neurons, whereas they did in control muscle and endothelial cell lines. Despite the lack of evidence of inflammatory signaling, saturated fatty acid exposure in cultured hypothalamic neurons causes endoplasmic reticulum stress, induces mitogen-activated protein kinase, and causes apoptotic cell death with prolonged exposure. We conclude that saturated fatty acid exposure does not induce inflammatory signaling or insulin resistance in cultured hypothalamic neurons. Therefore, hypothalamic neuronal inflammation in the setting of DIO may involve an indirect mechanism mediated by saturated fatty acids on nonneuronal cells.

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Abstract 357: Hepatic ERK2 Suppresses Endoplasmic Reticulum Stress, Leading to Protection from Oxidative Stress and Endothelial Dysfunction

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.33.suppl_1.a357 ◽

2013 ◽

Vol 33 (suppl_1) ◽

Author(s):

Takehiko Kujiraoka ◽

Yasushi Satoh ◽

Makoto Ayaori ◽

Yasunaga Shiraishi ◽

Yuko Arai-Nakaya ◽

...

Keyword(s):

Oxidative Stress ◽

Insulin Resistance ◽

Endoplasmic Reticulum ◽

Fatty Acid ◽

Endothelial Dysfunction ◽

Er Stress ◽

Vascular Complications ◽

Metabolic Remodeling ◽

And Oxidative Stress

Background Insulin signaling comprises 2 major cascades, the IRS/PI3K/Akt and Ras/Raf/MEK/ERK pathways. Many studies on the tissue-specific effects of the former pathway had been conducted, however, the role of the latter cascade in tissue-specific insulin resistance had not been investigated. High glucose/fatty acid toxicity, inflammation and oxidative stress, all of which are associated with insulin resistance, can activate ERK. Liver plays a central role of metabolism and hepatosteatosis (HST) is associated with vascular diseases. The aim of this study is to elucidate the role of hepatic ERK2 in HST, metabolic remodeling and endothelial dysfunction. Methods Serum biomarkers of vascular complications in human were compared between subjects with and without HST diagnosed by echography for regular medical checkup. Next, we created liver-specific ERK2 knockout mice (LE2KO) and fed them with a high-fat/high-sucrose diet (HFHSD) for 20 weeks. The histological analysis, the expression of hepatic sarco/endoplasmic reticulum (ER) Ca 2+ -ATPase 2 (SERCA2) and glucose-tolerance/insulin-sensitivity (GT/IS) were tested. Vascular superoxide production and endothelial function were evaluated with dihydroethidium staining and isometric tension measurement of aorta. Results The presence of HST significantly increased HOMA-IR, an indicator of insulin resistance or atherosclerotic index in human. HFHSD-fed LE2KO revealed a marked exacerbation in HST and metabolic remodeling represented by the impairment of GT/IS, elevated serum free fatty acid and hyperhomocysteinemia without changes in body weight, blood pressure and serum cholesterol/triglyceride levels. In the HFHSD-fed LE2KO, mRNA and protein expressions of hepatic SERCA2 were significantly decreased, which resulted in hepatic ER stress. Induction of vascular superoxide production and remarkable endothelial dysfunction were also observed in them. Conclusions Hepatic ERK2 revealed the suppression of hepatic ER stress and HST in vivo , which resulted in protection from vascular oxidative stress and endothelial dysfunction. HST with hepatic ER stress can be a prominent risk of vascular complications by metabolic remodeling and oxidative stress in obese-related diseases.

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