Apoptosis in skeletal muscle myotubes is induced by ceramides and is positively related to insulin resistance

2006 ◽  
Vol 291 (6) ◽  
pp. E1341-E1350 ◽  
Author(s):  
Sarah M. Turpin ◽  
Graeme I. Lancaster ◽  
Ian Darby ◽  
Mark A. Febbraio ◽  
Matthew J. Watt
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Metabolic Syndrome ◽  
Fatty Acid ◽  
Glucose Uptake ◽  
Protein Content ◽  
The Metabolic Syndrome ◽  
Effector Caspase ◽  
Induced Apoptosis ◽  
Ceramide Accumulation

Fatty acid-induced apoptosis occurs in pancreatic β-cells and contributes to the metabolic syndrome. Skeletal muscle insulin resistance is mediated by fatty acid oversupply, which also contributes to the metabolic syndrome. Therefore, we examined whether fatty acids induce apoptosis in skeletal muscle myotubes, the proapoptotic signaling involved, and the effects on insulin sensitivity. Exposure of L6 myotubes to palmitate induced apoptosis, as demonstrated by increased caspase-3 activation, phosphatidylserine exposure on the plasma membrane, and terminal deoxynucleotide transferase dUTP nick end labeling and DNA laddering, both markers of DNA fragmentation. Ceramide content was concomitantly increased, indicating a potential role for ceramides in palmitate-induced apoptosis. Supporting this notion, reducing stearoyl-CoA desaturase-1 (SCD-1) protein content with short interfering RNA resulted in ceramide accumulation and was associated with increased apoptosis in the absence of palmitate. Furthermore, the membrane-permeable C2-ceramide enhanced apoptosis in myotubes, whereas the ceramide synthase inhibitor, fumonisin B1, abrogated the proapoptotic effects of palmitate. Insulin-stimulated glucose uptake was inhibited by palmitate treatment, whereas the addition of effector caspase inhibitors [Ac-DEVD-aldehyde (DEVD-CHO), Z-DQMD-FMK] independently restored >80% of the insulin-stimulated glucose uptake. These effects were observed independently from changes in the protein content of insulin signaling proteins, suggesting that proteosomal degradation is not involved in this process. We conclude that lipoapoptosis occurs in skeletal muscle myotubes, at least partially via de novo ceramide accumulation, and that inhibiting downstream apoptotic signaling improves glucose uptake in vitro.

Dietary lipids and gene expression

2004 ◽  
Vol 32 (6) ◽  
pp. 999-1002 ◽  
Author(s):  
H.M. Roche
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Transcription Factors ◽  
Fatty Acid ◽  
Regulatory Element ◽  
Nuclear Factor Κb ◽  
Dietary Lipids ◽  
Dietary Fatty Acids ◽  
Dietary Fatty Acid ◽  
The Metabolic Syndrome

Nutrition is a key environmental factor that is particularly involved in the pathogenesis and progression of several polygenic, diet-related diseases. Nutrigenomics refers to the interaction between nutrition and the human genome. Dietary fatty acids interact with multiple nutrient-sensitive transcription factors. This explains the molecular basis of some of the health effects associated with altered dietary fatty acid composition. The metabolic syndrome is a very common condition, characterized by insulin resistance, abdominal obesity, dyslipidaemia and hypertension. It often precedes Type 2 diabetes mellitus, and is associated with a greater risk of cardiovascular disease. Several lines of evidence suggest that the interaction between nutrient-derived metabolic stressors and pro-inflammatory signals play an important role in the aetiology of insulin resistance and the development of the metabolic syndrome. This paper will address the interaction between several nutrient-sensitive transcription factors, including SREBP (sterol-regulatory-element-binding protein) and NFκB (nuclear factor κB), demonstrating how this interaction may be altered with dietary fatty acid interventions.

scholarly journals Upregulation of skeletal muscle inflammatory genes links inflammation with insulin resistance in women with the metabolic syndrome

2013 ◽  
Vol 98 (10) ◽  
pp. 1485-1494 ◽  
Author(s):  
Fleur Poelkens ◽  
Gerwen Lammers ◽  
Elisabeth M. Pardoel ◽  
Cees J. Tack ◽  
Maria T. E. Hopman
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Metabolic Syndrome ◽  
Inflammatory Genes ◽  
The Metabolic Syndrome

scholarly journals Calpain-10 interacts with plasma saturated fatty acid concentrations to influence insulin resistance in individuals with the metabolic syndrome

2011 ◽  
Vol 93 (5) ◽  
pp. 1136-1141 ◽  
Author(s):  
Pablo Perez-Martinez ◽  
Javier Delgado-Lista ◽  
Antonio Garcia-Rios ◽  
Jane F Ferguson ◽  
Hanne L Gulseth ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Fatty Acid ◽  
Saturated Fatty Acid ◽  
The Metabolic Syndrome ◽  
Calpain 10

scholarly journals Muscle-specific Pikfyve gene disruption causes glucose intolerance, insulin resistance, adiposity, and hyperinsulinemia but not muscle fiber-type switching

2013 ◽  
Vol 305 (1) ◽  
pp. E119-E131 ◽  
Author(s):  
Ognian C. Ikonomov ◽  
Diego Sbrissa ◽  
Khortnal Delvecchio ◽  
Han-Zhong Feng ◽  
Gregory D. Cartee ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Fatty Acid ◽  
Glucose Uptake ◽  
Glucose Intolerance ◽  
Fat Mass ◽  
Gene Disruption ◽  
Glut4 Translocation ◽  
Fat Cell

The evolutionarily conserved kinase PIKfyve that synthesizes PtdIns5P and PtdIns(3,5)P2 has been implicated in insulin-regulated GLUT4 translocation/glucose entry in 3T3-L1 adipocytes. To decipher PIKfyve's role in muscle and systemic glucose metabolism, here we have developed a novel mouse model with Pikfyve gene disruption in striated muscle (MPIfKO). These mice exhibited systemic glucose intolerance and insulin resistance at an early age but had unaltered muscle mass or proportion of slow/fast-twitch muscle fibers. Insulin stimulation of in vivo or ex vivo glucose uptake and GLUT4 surface translocation was severely blunted in skeletal muscle. These changes were associated with premature attenuation of Akt phosphorylation in response to in vivo insulin, as tested in young mice. Starting at 10–11 wk of age, MPIfKO mice progressively accumulated greater body weight and fat mass. Despite increased adiposity, serum free fatty acid and triglyceride levels were normal until adulthood. Together with the undetectable lipid accumulation in liver, these data suggest that lipotoxicity and muscle fiber switching do not contribute to muscle insulin resistance in MPIfKO mice. Furthermore, the 80% increase in total fat mass resulted from increased fat cell size rather than altered fat cell number. The observed profound hyperinsulinemia combined with the documented increases in constitutive Akt activation, in vivo glucose uptake, and gene expression of key enzymes for fatty acid biosynthesis in MPIfKO fat tissue suggest that the latter is being sensitized for de novo lipid anabolism. Our data provide the first in vivo evidence that PIKfyve is essential for systemic glucose homeostasis and insulin-regulated glucose uptake/GLUT4 translocation in skeletal muscle.

Sodium/lithium countertransport, insulin resistance, insulin peptides and microalbuminuria in clinically healthy 58-year-old men

2001 ◽  
Vol 100 (4) ◽  
pp. 443-449 ◽  
Author(s):  
Hans HERLITZ ◽  
Lena BOKEMARK ◽  
Eva-Lena ALENHAG ◽  
John WIKSTRAND ◽  
Björn FAGERBERG
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Insulin Sensitivity ◽  
Glucose Uptake ◽  
Univariate Analysis ◽  
Serum Triglycerides ◽  
The Metabolic Syndrome ◽  
Significant Difference ◽  
N 93 ◽  
Old Men

The activity of the erythrocyte transport system, sodium/lithium countertransport (SLC), has been linked to the metabolic syndrome characterized by insulin resistance and compensatory hyperinsulinaemia. We measured SLC and insulin sensitivity with the euglycaemic hyperinsulinaemic clamp method in a patient sample (n = 93) randomly selected from a large clinically healthy group of 58-year-old men (n = 818). The lipid profile, blood pressure, body mass index (BMI) and insulin were also analysed. There was a significant difference (P < 0.001) in SLC between subjects with the metabolic syndrome (n = 19) and subjects without any components of this syndrome (n = 20). There was a highly significant correlation between SLC and BMI, waist/hip ratio, total body fat mass, serum triglycerides, plasma insulin, proinsulin split products and C-peptide in a univariate analysis. There was also a significant correlation between SLC and insulin sensitivity measured as insulin-mediated glucose uptake (P < 0.01). In multiple regression analysis, only two of the variables showing univariate significance were independently correlated to SLC, i.e. serum triglycerides (P < 0.001) and BMI (P < 0.01). The subjects with a SLC value in the highest tertile had a 6-fold higher prevalence of insulin resistance (low-insulin-mediated glucose uptake) as compared with those with a SLC value in the lowest tertile. We conclude that, in clinically healthy 58-year-old men from the general population, erythrocyte SLC is closely linked to metabolic syndrome, in particular to obesity, triglycerides and insulin resistance.

scholarly journals Mechanisms of the components of the metabolic syndrome that predispose to diabetes and atherosclerotic CVD

2007 ◽  
Vol 66 (1) ◽  
pp. 82-95 ◽  
Author(s):  
Robert H. Eckel
Keyword(s):  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Metabolic Syndrome ◽  
Fatty Acid ◽  
Inflammatory Cytokines ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
The Metabolic Syndrome ◽  
Pro Inflammatory Cytokines

The metabolic syndrome represents a summation of obesity-driven risk factors for atherosclerotic CVD and type 2 diabetes. Definitions of the syndrome vary but in general agree closely in identifying subjects. The relationships between the metabolic syndrome and atherosclerotic CVD and diabetes also vary, with relative risks of approximately 1·5–3·0 and approximately 3·0–5·0 respectively. Insulin resistance appears to explain much of the pathophysiology of the syndrome. Both increased fatty acid flux and an excess of circulating pro-inflammatory cytokines are likely mediators. With increased waist circumference, increases in fatty acid delivery to the liver result in higher rates of hepatic glucose production and increases in the secretion of apoB-containing lipoproteins. Concomitant changes in HDL ensue, including a replacement of the cholesterol content with TAG, an accelerated clearance from the plasma and thus a reduced number of HDL particles. Typically also present are increases in small dense LDL. Hypertension in part relates to the insulin resistance, but may involve other mechanisms. Impaired fasting glucose often relates to defects in insulin secretion in addition to insulin resistance, and probably more than any other component of the syndrome predicts the increased incidence of type 2 diabetes. Although not included in the diagnostic criteria, increases in pro-inflammatory cytokines and pro-thrombotic factors, in addition to decreases in plasma adiponectin, may also contribute to the increased incidence of atherosclerotic CVD and diabetes. In general, the greater the number of metabolic syndrome components, the greater the risk for these outcomes. The cytokines and pro-thrombotic factors also appear to contribute.

scholarly journals Adipocyte Fatty Acid–Binding Protein Is a Plasma Biomarker Closely Associated with Obesity and Metabolic Syndrome

2006 ◽  
Vol 52 (3) ◽  
pp. 405-413 ◽  
Author(s):  
Aimin Xu ◽  
Yu Wang ◽  
Jian Yu Xu ◽  
David Stejskal ◽  
Sidney Tam ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Fatty Acid ◽  
Human Serum ◽  
Fatty Acid Binding Protein ◽  
Binding Protein ◽  
Model Assessment ◽  
Fatty Acid Binding ◽  
Acid Binding Protein ◽  
The Metabolic Syndrome

Abstract Background: Adipocyte fatty acid–binding protein (A-FABP) is traditionally thought to be a cytosolic fatty acid chaperone expressed in adipocytes. Mice with targeted disruption of the A-FABP gene exhibit a striking phenotype with strong protection from insulin resistance, hyperglycemia, and atherosclerosis. The clinical relevance of these findings remains to be confirmed. Methods: We used tandem mass spectrometry–based proteomic analysis to identify proteins secreted from adipocytes and present in human serum. We measured serum A-FABP concentrations in 229 persons (121 men and 108 women; age range, 33–72 years), including 100 lean [body mass index (BMI) &lt;25 kg/m2] and 129 overweight/obese individuals (BMI &gt;25 kg/m2) selected from a previous cross-sectional study. Results: A-FABP was released from adipocytes and was abundantly present in human serum. Mean (SD) circulating concentrations of A-FABP were significantly higher in overweight/obese than in lean persons [32.3 (14.8) vs 20.0 (9.8) μg/L; P &lt;0.001]. Age- and sex-adjusted serum A-FABP concentrations correlated positively (P &lt;0.005) with waist circumference, blood pressure, dyslipidemia, fasting insulin, and the homeostasis model assessment insulin resistance index. Moreover, we observed a significant increase in A-FABP concentrations corresponding with increases in the number of components of the metabolic syndrome (P &lt;0.05). Conclusions: A-FABP is a circulating biomarker closely associated with obesity and components of the metabolic syndrome, and measurement of serum concentrations of A-FABP might be useful for clinical diagnosis of obesity-related metabolic and cardiovascular disorders.

scholarly journals Fenofibrate Reverses Palmitate Induced Impairment in Glucose Uptake in Skeletal Muscle Cells by Preventing Cytosolic Ceramide Accumulation

2015 ◽  
Vol 37 (4) ◽  
pp. 1315-1328 ◽  
Author(s):  
Sudarshan Bhattacharjee ◽  
Nabanita Das ◽  
Ashok Mandala ◽  
Satinath Mukhopadhyay ◽  
Sib Sankar Roy
Keyword(s):  
Insulin Resistance ◽  
Fatty Acid ◽  
Glucose Uptake ◽  
Fatty Acid Oxidation ◽  
Acid Oxidation ◽  
Stoichiometric Ratio ◽  
Mrna Levels ◽  
L6 Myotubes ◽  
Hypolipidemic Agents ◽  
Ceramide Accumulation

Backgrounds/Aims: The lipid induced insulin resistance is a major pathophysiologic mechanism underlying glucose intolerance of varying severity. PPARα-agonists are proven as effective hypolipidemic agents. The aim of this study was to see if impaired glucose uptake in palmitate treated myotubes is reversed by fenofibrate. Methods: Palmitate-treated myotubes were used as a model for insulin resistance, impaired glucose uptake, fatty acid oxidation and ceramide synthesis. mRNA levels of CPT1 and CPT2 were determined by PCR array and Q-PCR. Results: The incubation of myotubes with 750 uM palmitate not only reduced glucose uptake but also impaired fatty acid oxidation and cytosolic ceramide accumulation. Palmitate upregulated CPT1b expression in L6 myotubes, while CPT2 expression level remained unchanged. The altered stoichiometric ratio between the two CPT isoforms led to reduced fatty acid oxidation (FAO), ceramide accumulation and impaired glucose uptake, whereas administration of 200 µM fenofibrate signifcantly reversed the above abnormalities by increasing CPT2 mRNA levels and restoring CPT1b to CPT2 ratio. Conclusion: Palmitate-induced alteration in the stoichiometric ratio of mitochondrial CPT isoforms leads to incomplete FAO and enhanced cytosolic ceramide accumulation that lead to insulin resistance. Fenofibrate ameliorated insulin resistance by restoring the altered stoichiometry by upregulating CPT2 and preventing, cytoplasmic ceramide accumulation.

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