Modulation of Insulin Resistance and the Adipocyte-Skeletal Muscle Cell Cross-Talk by LCn-3PUFA

The cross-talk between skeletal muscle and adipose tissue is involved in the development of insulin resistance (IR) in skeletal muscle, leading to the decrease in the anabolic effect of insulin. We investigated if the long chain polyunsaturated n-3 fatty acids (LCn-3PUFA), eicosapentaenoic and docosapentaenoic acids (EPA and DPA, respectively) could (1) regulate the development of IR in 3T3-L1 adipocytes and C2C12 muscle cells and (2) inhibit IR in muscle cells exposed to conditioned media (CM) from insulin-resistant adipocytes. Chronic insulin (CI) treatment of adipocytes and palmitic acid (PAL) exposure of myotubes were used to induce IR in the presence, or not, of LCn-3PUFA. EPA (50 µM) and DPA (10 µM) improved PAL-induced IR in myotubes, but had only a partial effect in adipocytes. CM from adipocytes exposed to CI induced IR in C2C12 myotubes. Although DPA increased the mRNA levels of genes involved in fatty acid (FA) beta-oxidation and insulin signaling in adipocytes, it was not sufficient to reduce the secretion of inflammatory cytokines and prevent the induction of IR in myotubes exposed to adipocyte’s CM. Treatment with DPA was able to increase the release of adiponectin by adipocytes into CM. In conclusion, DPA is able to protect myotubes from PAL-induced IR, but not from IR induced by CM from adipocytes.

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RNA-sequencing analysis reveals the potential contribution of lncRNAs in palmitic acid-induced insulin resistance of skeletal muscle cells

Bioscience Reports ◽

10.1042/bsr20192523 ◽

2020 ◽

Vol 40 (1) ◽

Cited By ~ 1

Author(s):

Mei Han ◽

Lianghui You ◽

Yanting Wu ◽

Nan Gu ◽

Yan Wang ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Palmitic Acid ◽

Signaling Pathway ◽

Rna Sequencing ◽

Metabolic Diseases ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

C2c12 Myotubes ◽

Insulin Resistant

Abstract Insulin resistance (IR) has been considered as the common pathological basis and developmental driving force for most metabolic diseases. Long noncoding RNAs (lncRNAs) have emerged as pivotal regulators in modulation of glucose and lipid metabolism. However, the comprehensive profile of lncRNAs in skeletal muscle cells under the insulin resistant status and the possible biological effects of them were not fully studied. In this research, using C2C12 myotubes as cell models in vitro, deep RNA-sequencing was performed to profile lncRNAs and mRNAs between palmitic acid-induced IR C2C12 myotubes and control ones. The results revealed that a total of 144 lncRNAs including 70 up-regulated and 74 down-regulated (|fold change| > 2, q < 0.05) were significantly differentially expressed in palmitic acid-induced insulin resistant cells. In addition, functional annotation analysis based on the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases revealed that the target genes of the differentially expressed lncRNAs were significantly enriched in fatty acid oxidation, lipid oxidation, PPAR signaling pathway, and insulin signaling pathway. Moreover, Via qPCR, most of selected lncRNAs in myotubes and db/db mice skeletal muscle showed the consistent expression trends with RNA-sequencing. Co-expression analysis also explicated the key lncRNA–mRNA interactions and pointed out a potential regulatory network of candidate lncRNA ENSMUST00000160839. In conclusion, the present study extended the skeletal muscle lncRNA database and provided novel potential regulators for future genetic and molecular studies on insulin resistance, which is helpful for prevention and treatment of the related metabolic diseases.

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Hepatokine ERAP1 impairs skeletal muscle insulin sensitivity via ADRB2/PKA pathway

10.21203/rs.3.rs-37586/v1 ◽

2020 ◽

Author(s):

Feifan Guo ◽

Yuguo Niu ◽

Haizhou Jiang ◽

Hanrui Yin ◽

Fenfen Wang ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Sensitivity ◽

Neutralizing Antibodies ◽

Leptin Receptor ◽

Whole Body ◽

C2c12 Myotubes ◽

Insulin Resistant ◽

Skeletal Muscle Insulin Sensitivity ◽

Pka Pathway

Abstract The current study aimed to investigate the role of endoplasmic reticulum aminopeptidase 1 (ERAP1), a novel hepatokine, in whole-body glucose metabolism. Here, we found that hepatic ERAP1 levels were increased in insulin-resistant leptin-receptor-mutated (db/db) and high-fat diet (HFD)-fed mice. Consistently, hepatic ERAP1 overexpression attenuated skeletal muscle (SM) insulin sensitivity, whereas knockdown ameliorated SM insulin resistance. Furthermore, serum and hepatic ERAP1 levels were positively correlated, and recombinant mouse ERAP1 or conditioned medium with high ERAP1 content (CM-ERAP1) attenuated insulin signaling in C2C12 myotubes, and CM-ERAP1 or HFD-induced insulin resistance was blocked by ERAP1 neutralizing antibodies. Mechanistically, ERAP1 reduced ADRB2 expression and interrupted ADRB2-dependent signaling in C2C12 myotubes. Finally, ERAP1 inhibition via global knockout or the inhibitor thimerosal improved insulin sensitivity. Together, ERAP1 is a hepatokine that impairs SM and whole-body insulin sensitivity, and its inhibition might provide a therapeutic strategy for diabetes, particularly for those with SM insulin resistance.

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Mammalian Tribbles homolog 3 impairs insulin action in skeletal muscle: role in glucose-induced insulin resistance

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00467.2009 ◽

2010 ◽

Vol 298 (3) ◽

pp. E565-E576 ◽

Cited By ~ 46

Author(s):

Jiarong Liu ◽

Xuxia Wu ◽

John L. Franklin ◽

Joseph L. Messina ◽

Helliner S. Hill ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Glucose Transporter ◽

Vastus Lateralis ◽

Glucose Deprivation ◽

Muscle Cells ◽

Diabetic Rats ◽

Glucose Disposal ◽

Insulin Resistant ◽

Protein Levels

Tribbles homolog 3 (TRIB3) was found to inhibit insulin-stimulated Akt phosphorylation and modulate gluconeogenesis in rodent liver. Currently, we examined a role for TRIB3 in skeletal muscle insulin resistance. Ten insulin-sensitive, ten insulin-resistant, and ten untreated type 2 diabetic (T2DM) patients were metabolically characterized by hyperinsulinemic euglycemic glucose clamps, and biopsies of vastus lateralis were obtained. Skeletal muscle samples were also collected from rodent models including streptozotocin (STZ)-induced diabetic rats, db/db mice, and Zucker fatty rats. Finally, L6 muscle cells were used to examine regulation of TRIB3 by glucose, and stable cell lines hyperexpressing TRIB3 were generated to identify mechanisms underlying TRIB3-induced insulin resistance. We found that 1) skeletal muscle TRIB3 protein levels are significantly elevated in T2DM patients; 2) muscle TRIB3 protein content is inversely correlated with glucose disposal rates and positively correlated with fasting glucose; 3) skeletal muscle TRIB3 protein levels are increased in STZ-diabetic rats, db/db mice, and Zucker fatty rats; 4) stable TRIB3 hyperexpression in muscle cells blocks insulin-stimulated glucose transport and glucose transporter 4 (GLUT4) translocation and impairs phosphorylation of Akt, ERK, and insulin receptor substrate-1 in insulin signal transduction; and 5) TRIB3 mRNA and protein levels are increased by high glucose concentrations, as well as by glucose deprivation in muscle cells. These data identify TRIB3 induction as a novel molecular mechanism in human insulin resistance and diabetes. TRIB3 acts as a nutrient sensor and could mediate the component of insulin resistance attributable to hyperglycemia (i.e., glucose toxicity) in diabetes.

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Apelin and APJ regulation in adipose tissue and skeletal muscle of type 2 diabetic mice and humans

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00598.2009 ◽

2010 ◽

Vol 298 (6) ◽

pp. E1161-E1169 ◽

Cited By ~ 83

Author(s):

Cédric Dray ◽

Cyrille Debard ◽

Jennifer Jager ◽

Emmanuel Disse ◽

Danièle Daviaud ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Adipose Tissue ◽

Receptor Expression ◽

Diabetic Patients ◽

Mrna Levels ◽

Type 2 Diabetic Patients ◽

Insulin Resistant ◽

Type 2 Diabetic

Apelin, an adipocyte-secreted factor upregulated by insulin, is increased in adipose tissue (AT) and plasma with obesity. Apelin was recently identified as a new player in the control of glucose homeostasis. However, the regulation of apelin and APJ (apelin receptor) expression in skeletal muscle in relation to insulin resistance or type 2 diabetes is not known. Thus we studied apelin and APJ expression in AT and muscle in different mice models of obesity and in type 2 diabetic patients. In insulin-resistant high-fat (HF)-fed mice, apelin and APJ expression were increased in AT compared with control. This was not the case in AT of highly insulin-resistant db/ db mice. In skeletal muscle, apelin expression was similar in control and HF-fed mice and decreased in db/ db mice. APJ expression was decreased in both HF-fed and db/ db mice. Control subjects and type 2 diabetic patients were subjected to a hyperinsulinemic-euglycemic clamp, and tissues biopsies were obtained before and at the end of the clamp. There was no significant difference in basal apelin and APJ expression in AT and muscle between control and diabetic patients. However, apelin plasma levels were significantly increased in diabetic patients. During the clamp, hyperinsulinemia increased apelin and APJ expression in AT of control but not in diabetic subjects. In muscle, only APJ mRNA levels were increased in control but also in diabetic patients. Taken together, these data show that apelin and APJ expression in mice and humans is regulated in a tissue-dependent manner and according to the severity of insulin resistance.

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eEF1A2 exacerbated insulin resistance in male skeletal muscle via PKCβ and ER stress

Journal of Endocrinology ◽

10.1530/joe-19-0051 ◽

2020 ◽

Vol 244 (1) ◽

pp. 25-40 ◽

Cited By ~ 2

Author(s):

Meng Guo ◽

Yuna Li ◽

Yan Wang ◽

Zhenkun Li ◽

Xiaohong Li ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Sensitivity ◽

Er Stress ◽

Lentiviral Vector ◽

C2c12 Myotubes ◽

Mongolian Gerbils ◽

Suppression Subtractive Hybridisation ◽

Translation Elongation ◽

Insulin Resistant

Recent studies raise the possibility that eukaryotic translation elongation factor 1 alpha (eEF1A) may play a role in metabolism. One isoform, eEF1A2, is specifically expressed in skeletal muscle, heart and brain. It regulates translation elongation and signal transduction. Nonetheless, eEF1A2’s function in skeletal muscle glucose metabolism remains unclear. In the present study, suppression subtractive hybridisation showed a decrease in Eef1a2 transcripts in the skeletal muscle of diabetic Mongolian gerbils. This was confirmed at mRNA and protein levels in hyperglycaemic gerbils, and in db/db and high-fat diet-fed mice. Further, this downregulation was independent of Eef1a2 promoter methylation. Interestingly, adeno-associated virus-mediated eEF1A2 overexpression in skeletal muscle aggravated fasting hyperglycaemia, hyperinsulinaemia and glucose intolerance in male diabetic gerbils but not in female gerbil models. The overexpression of eEF1A2 in skeletal muscle also resulted in promoted serum glucose levels and insulin resistance in male db/db mice. Up- and downregulation of eEF1A2 by lentiviral vector transfection confirmed its inhibitory effect on insulin-stimulated glucose uptake and signalling transduction in C2C12 myotubes with palmitate (PA)-induced insulin resistance. Furthermore, eEF1A2 bound PKCβ and increased its activation in the cytoplasm, whereas suppression of PKCβ by an inhibitor attenuated eEF1A2-mediated impairment of insulin sensitivity in insulin-resistant myotubes. Endoplasmic reticulum (ER) stress was elevated by eEF1A2, whereas suppression of ER stress or JNK partially restored insulin sensitivity in PA-treated myotubes. Additionally, eEF1A2 inhibited lipogenesis and lipid utilisation in insulin-resistant skeletal muscle. Collectively, we demonstrated that eEF1A2 exacerbates insulin resistance in male murine skeletal muscle via PKCβ and ER stress.

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Vitamin D Ameliorates Fat Accumulation with AMPK/SIRT1 Activity in C2C12 Skeletal Muscle Cells

Nutrients ◽

10.3390/nu11112806 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2806 ◽

Cited By ~ 7

Author(s):

Eugene Chang ◽

Yangha Kim

Keyword(s):

Vitamin D ◽

Mitochondrial Dysfunction ◽

Muscle Cells ◽

C2c12 Myotubes ◽

Mrna Levels ◽

Fat Accumulation ◽

Chain Acyl ◽

C2c12 Muscle Cells ◽

Long Chain ◽

Significant Increment

Excessive fat accumulation has been considered as a major contributing factor for muscle mitochondrial dysfunction and its associated metabolic complications. The purpose of present study is to investigate a role of vitamin D in muscle fat accumulation and mitochondrial changes. In differentiated C2C12 muscle cells, palmitic acid (PA) was pretreated, followed by incubation with 1,25-dihyroxyvitamin D (1,25(OH)2D) for 24 h. PA led to a significant increment of triglyceride (TG) levels with increased lipid peroxidation and cellular damage, which were reversed by 1,25(OH)2D. The supplementation of 1,25(OH)2D significantly enhanced PA-decreased mtDNA levels as well as mRNA levels involved in mitochondrial biogenesis such as nuclear respiratory factor 1 (NRF1), peroxisome proliferative activated receptor gamma coactivator-1α (PGC-1α), and mitochondrial transcription factor A (Tfam) in C2C12 myotubes. Additionally, 1,25(OH)2D significantly increased ATP levels and gene expression related to mitochondrial function such as carnitine palmitoyltransferase 1 (CPT1), peroxisome proliferator-activated receptor α (PPARα), very long-chain acyl-CoA dehydrogenase (VLCAD), long-chain acyl-CoA dehydrogenase (LCAD), medium-chain acyl-CoA dehydrogenase (MCAD), uncoupling protein 2 (UCP2), and UCP3 and the vitamin D pathway including 25-dihydroxyvitamin D3 24-hydroxylase (CYP24) and 25-hydroxyvitamin D3 1-alpha-hydroxylase (CYP27) in PA-treated C2C12 myotubes. In addition to significant increment of sirtuin 1 (SIRT1) mRNA expression, increased activation of adenosine monophosphate-activated protein kinase (AMPK) and SIRT1 was found in 1,25(OH)2D-treated C2C12 muscle cells. Thus, we suggest that the observed protective effect of vitamin D on muscle fat accumulation and mitochondrial dysfunction in a positive manner via modulating AMPK/SIRT1 activation.

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Skeletal muscle insulin resistance induced by adipocyte-conditioned medium: underlying mechanisms and reversibility

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00529.2007 ◽

2008 ◽

Vol 294 (6) ◽

pp. E1070-E1077 ◽

Cited By ~ 45

Author(s):

Henrike Sell ◽

Kristin Eckardt ◽

Annika Taube ◽

Daniel Tews ◽

Mihaela Gurgui ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Conditioned Medium ◽

Insulin Signaling ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Insulin Resistant ◽

Enhanced Production ◽

Human Myotubes ◽

Human Skeletal Muscle Cells

Insulin resistance in skeletal muscle is an early event in the development of diabetes, with obesity being one of the major contributing factors. In vitro, conditioned medium (CM) from differentiated human adipocytes impairs insulin signaling in human skeletal muscle cells, but it is not known whether insulin resistance is reversible and which mechanisms may underlie this process. CM induced insulin resistance in human myotubes at the level of insulin-stimulated Akt and GSK-3 phosphorylation. In addition, insulin-resistant skeletal muscle cells exhibit enhanced production of reactive oxygen species and ceramide as well as a downregulation of myogenic transcription factors such as myogenin and MyoD. However, insulin resistance was not paralleled by increased apopotosis. Regeneration of myotubes for 24 or 48 h after induction of insulin resistance restored normal insulin signaling. However, the expression level of myogenin could not be reestablished. In addition to decreasing myogenin expression, CM also decreased the release of IL-6 and IL-8 and increased monocyte chemotactic protein-1 (MCP-1) secretion from skeletal muscle cells. Although regeneration of myotubes reestablished normal secretion of IL-6, the release of IL-8 and MCP-1 remained impaired for 48 h after withdrawal of CM. In conclusion, our data show that insulin resistance in skeletal muscle cells is only partially reversible. Although some characteristic features of insulin-resistant myotubes normalize in parallel to insulin signaling after withdrawal of CM, others such as IL-8 and MCP-1 secretion and myogenin expression remain impaired over a longer period. Thus, we propose that the induction of insulin resistance may cause irreversible changes of protein expression and secretion in skeletal muscle cells.

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1,25-Dihydroxyvitamin D Decreases Tertiary Butyl-Hydrogen Peroxide-Induced Oxidative Stress and Increases AMPK/SIRT1 Activation in C2C12 Muscle Cells

Molecules ◽

10.3390/molecules24213903 ◽

2019 ◽

Vol 24 (21) ◽

pp. 3903 ◽

Cited By ~ 7

Author(s):

Chang

Keyword(s):

Oxidative Stress ◽

Vitamin D ◽

Myogenic Differentiation ◽

Mitochondrial Dynamics ◽

Muscle Cells ◽

Biologically Active ◽

C2c12 Myotubes ◽

Mrna Levels ◽

Tertiary Butyl ◽

C2c12 Muscle Cells

Enhanced oxidative stress has been associated with muscle mitochondrial changes and metabolic disorders. Thus, it might be a good strategy to decrease oxidative stress and improve mitochondrial changes in skeletal muscle. In the present study, we investigate the role of the most biologically active metabolite of vitamin D, 1,25-dihyroxyvitamin D (1,25(OH)2D) in oxidative stress and mitochondrial changes in tertiary butyl-hydrogen (tBHP)-treated C2C12 muscle cells. Differentiated C2C12 muscle cells were pretreated with tBHP, followed by 1,25(OH)2D for additional 24 h. An exogenous inducer of oxidative stress, tBHP significantly increased oxidative stress, lipid peroxidation, intracellular damage, and cell death which were reversed by 1,25(OH)2D in C2C12 myotubes. 1.25(OH)2D improves tBHP-induced mitochondrial morphological changes such as swelling, irregular cristae, and smaller size and number, as observed by transmission electron microscope. In addition, 1,25(OH)2D treatment increases mtDNA contents as well as gene expression involved in mitochondrial biogenesis such as PGC1α, NRF1, and Tfam. Significant increments in mRNA levels related to antioxidant enzymes such as Nrf2, HMOX1, and TXNRD1, myogenic differentiation markers including myoglobin, muscle creatine kinase (MCK), and MHCІ and ІІ, and vitamin D metabolism such as CYP24, CYP27, and vitamin D receptor (VDR) were found in 1,25(OH)2D-treated myotubes. Moreover, upon t-BHP-induced oxidative stress, significant incremental changes in nicotinamide adenine dinucleotide (NAD) levels, activities of AMP-activated protein kinase (AMPK)/sirtulin 1 (SIRT1), and SIRT1 expression were noted in 1,25(OH)2D-treated C2C12 muscle cells. Taken together, these results suggest the observed potent inhibitory effect of 1,25(OH)2D on muscle oxidative stress and mitochondrial dynamics might be at least involved in the activation of AMPK and SIRT1 activation in muscle cells.

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Activation of the Hexosamine Signaling Pathway in Adipose Tissue Results in Decreased Serum Adiponectin and Skeletal Muscle Insulin Resistance

Endocrinology ◽

10.1210/en.2003-0812 ◽

2004 ◽

Vol 145 (5) ◽

pp. 2118-2128 ◽

Cited By ~ 49

Author(s):

Mark Hazel ◽

Robert C. Cooksey ◽

Deborah Jones ◽

Glendon Parker ◽

John L. Neidigh ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Adipose Tissue ◽

Transgenic Mice ◽

Serum Adiponectin ◽

Glucose Disposal ◽

Mrna Levels ◽

Muscle Insulin Resistance ◽

Insulin Resistant ◽

Skeletal Muscle Insulin Resistance

Abstract Overexpression of the rate-limiting enzyme for hexosamine synthesis (glutamine:fructose-6-phosphate amidotransferase) in muscle and adipose tissue of transgenic mice was previously shown to result in insulin resistance and hyperleptinemia. Explanted muscle from transgenic mice was not insulin resistant in vitro, suggesting that muscle insulin resistance could be mediated by soluble factors from fat tissue. To dissect the relative contributions of muscle and fat to hexosamine-induced insulin resistance, we overexpressed glutamine:fructose-6-phosphate amidotransferase 2.5-fold, specifically in fat under control of the aP2 promoter. Fasting glucose, insulin, and triglycerides were unchanged in the transgenic mice; leptin and β-hydroxybutyrate levels were 91% and 29% higher, respectively. Fasted transgenic mice have mild glucose intolerance and skeletal muscle insulin resistance in vivo. In fasting transgenic mice, glucose disposal rates with hyperinsulinemia were decreased 27% in females and 10% in males. Uptake of 2-deoxy-d-glucose into muscle was diminished by 45% in female and 21% in male transgenics. Serum adiponectin was also lower in the fasted transgenics, by 37% in females and 22% in males. TNFα and resistin mRNA levels in adipose tissue were not altered in the fasted transgenics; levels of mRNA for leptin were increased and peroxisome proliferator-activated receptor γ decreased. To further explore the relationship between adiponectin and insulin sensitivity, we examined mice that have been refed for 6 h after a 24-h fast. Refeeding wild-type mice resulted in decreased serum adiponectin and increased leptin. In transgenic mice, however, the regulation of these hormones by refeeding was lost for adiponectin and diminished for leptin. Refed transgenic female and male mice no longer exhibited decreased serum adiponectin in the refed state, and they were no longer insulin resistant as by lower or unchanged insulin and glucose levels. We conclude that increased hexosamine levels in fat, mimicking excess nutrient delivery, are sufficient to cause insulin resistance in skeletal muscle. Changes in serum adiponectin correlate with the insulin resistance of the transgenic animals.

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