scholarly journals Comparative profiling of skeletal muscle models reveals heterogeneity of transcriptome and metabolism

2020 ◽  
Vol 318 (3) ◽  
pp. C615-C626 ◽  
Author(s):  
Ahmed M. Abdelmoez ◽  
Laura Sardón Puig ◽  
Jonathon A. B. Smith ◽  
Brendan M. Gabriel ◽  
Mladen Savikj ◽  
...  
Keyword(s):  
Experimental Data ◽  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glycogen Synthesis ◽  
C2c12 Myotubes ◽  
Mrna Levels ◽  
Cellular Models ◽  
L6 Myotubes ◽  
Human Myotubes ◽  
Human Skeletal Muscle Cells

Rat L6, mouse C2C12, and primary human skeletal muscle cells (HSMCs) are commonly used to study biological processes in skeletal muscle, and experimental data on these models are abundant. However, consistently matched experimental data are scarce, and comparisons between the different cell types and adult tissue are problematic. We hypothesized that metabolic differences between these cellular models may be reflected at the mRNA level. Publicly available data sets were used to profile mRNA levels in myotubes and skeletal muscle tissues. L6, C2C12, and HSMC myotubes were assessed for proliferation, glucose uptake, glycogen synthesis, mitochondrial activity, and substrate oxidation, as well as the response to in vitro contraction. Transcriptomic profiling revealed that mRNA of genes coding for actin and myosin was enriched in C2C12, whereas L6 myotubes had the highest levels of genes encoding glucose transporters and the five complexes of the mitochondrial electron transport chain. Consistently, insulin-stimulated glucose uptake and oxidative capacity were greatest in L6 myotubes. Insulin-induced glycogen synthesis was highest in HSMCs, but C2C12 myotubes had higher baseline glucose oxidation. All models responded to electrical pulse stimulation-induced glucose uptake and gene expression but in a slightly different manner. Our analysis reveals a great degree of heterogeneity in the transcriptomic and metabolic profiles of L6, C2C12, or primary human myotubes. Based on these distinct signatures, we provide recommendations for the appropriate use of these models depending on scientific hypotheses and biological relevance.

Contraction-related stimuli regulate GLUT4 traffic in C2C12-GLUT4myc skeletal muscle cells

2010 ◽  
Vol 298 (5) ◽  
pp. E1058-E1071 ◽  
Author(s):  
Wenyan Niu ◽  
Philip J. Bilan ◽  
Shuhei Ishikura ◽  
Jonathan D. Schertzer ◽  
Ariel Contreras-Ferrat ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Surface ◽  
Glucose Uptake ◽  
Nicotinic Acetylcholine Receptors ◽  
Cell Model ◽  
Cytosolic Calcium ◽  
Atpase Inhibitor ◽  
Cellular Models ◽  
Compound C

Muscle contraction stimulates glucose uptake acutely to increase energy supply, but suitable cellular models that faithfully reproduce this complex phenomenon are lacking. To this end, we have developed a cellular model of contracting C2C12 myotubes overexpressing GLUT4 with an exofacial myc-epitope tag (GLUT4 myc) and explored stimulation of GLUT4 traffic by physiologically relevant agents. Carbachol (an acetylcholine receptor agonist) induced a gain in cell surface GLUT4 myc that was mediated by nicotinic acetylcholine receptors. Carbachol also activated AMPK, and this response was sensitive to the contractile myosin ATPase inhibitor N-benzyl- p-toluenesulfonamide. The gain in surface GLUT4 myc elicited by carbachol or by the AMPK activator 5-amino-4-carboxamide-1 β-ribose was sensitive to chemical inhibition of AMPK activity by compound C and partially reduced by siRNA-mediated knockdown of AMPK catalytic subunits or LKB1. In addition, the carbachol-induced gain in cell surface GLUT4 myc was partially sensitive to chelation of intracellular calcium with BAPTA-AM. However, the carbachol-induced gain in cell surface GLUT4 myc was not sensitive to the CaMKK inhibitor STO-609 despite expression of both isoforms of this enzyme and a rise in cytosolic calcium by carbachol. Therefore, separate AMPK- and calcium-dependent signals contribute to mobilizing GLUT4 in response to carbachol, providing an in vitro cell model that recapitulates the two major signals whereby acute contraction regulates glucose uptake in skeletal muscle. This system will be ideal to further analyze the underlying molecular events of contraction-regulated GLUT4 traffic.

Does impaired mitochondrial function affect insulin signaling and action in cultured human skeletal muscle cells?

2008 ◽  
Vol 294 (1) ◽  
pp. E97-E102 ◽  
Author(s):  
Audrey E. Brown ◽  
Matthias Elstner ◽  
Stephen J. Yeaman ◽  
Douglass M. Turnbull ◽  
Mark Walker
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Insulin Signaling ◽  
Mitochondrial Respiration ◽  
Respiratory Function ◽  
Insulin Action ◽  
Human Skeletal Muscle ◽  
Human Skeletal Muscle Cells ◽  
Basal Glucose Uptake

Insulin-resistant type 2 diabetic patients have been reported to have impaired skeletal muscle mitochondrial respiratory function. A key question is whether decreased mitochondrial respiration contributes directly to the decreased insulin action. To address this, a model of impaired cellular respiratory function was established by incubating human skeletal muscle cell cultures with the mitochondrial inhibitor sodium azide and examining the effects on insulin action. Incubation of human skeletal muscle cells with 50 and 75 μM azide resulted in 48 ± 3% and 56 ± 1% decreases, respectively, in respiration compared with untreated cells mimicking the level of impairment seen in type 2 diabetes. Under conditions of decreased respiratory chain function, insulin-independent (basal) glucose uptake was significantly increased. Basal glucose uptake was 325 ± 39 pmol/min/mg (mean ± SE) in untreated cells. This increased to 669 ± 69 and 823 ± 83 pmol/min/mg in cells treated with 50 and 75 μM azide, respectively (vs. untreated, both P < 0.0001). Azide treatment was also accompanied by an increase in basal glycogen synthesis and phosphorylation of AMP-activated protein kinase. However, there was no decrease in glucose uptake following insulin exposure, and insulin-stimulated phosphorylation of Akt was normal under these conditions. GLUT1 mRNA expression remained unchanged, whereas GLUT4 mRNA expression increased following azide treatment. In conclusion, under conditions of impaired mitochondrial respiration there was no evidence of impaired insulin signaling or glucose uptake following insulin exposure in this model system.

Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle

2008 ◽  
Vol 294 (1) ◽  
pp. E28-E35 ◽  
Author(s):  
Michale Bouskila ◽  
Michael F. Hirshman ◽  
Jørgen Jensen ◽  
Laurie J. Goodyear ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Wild Type ◽  
Muscle Glycogen Synthesis ◽  
Mutant Forms

Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6- P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3α and -β genes are replaced with mutant forms (GSK3α/βS21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3α/βS21A/S21A/S9A/S9Amice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6- P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6- P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.

14-Deoxy-11,12-Didehydroandrographolide Ameliorates Glucose Intolerance Enhancing the LKB1/AMPKα/TBC1D1/GLUT4 Signaling Pathway and Inducing GLUT4 Expression in Myotubes and Skeletal Muscle of Obese Mice

2021 ◽  
pp. 1-19
Author(s):  
Chih-Chieh Chen ◽  
Chong-Kuei Lii ◽  
Chia-Wen Lo ◽  
Yi-Hsueh Lin ◽  
Ya-Chen Yang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Signaling Pathway ◽  
Nuclear Translocation ◽  
Time Dependent ◽  
Antidiabetic Activity ◽  
C2c12 Myotubes ◽  
Dependent Manner ◽  
Compound C

14-Deoxy-11,12-didehydroandrographolide (deAND), a bioactive component of Andrographis paniculata, has antidiabetic activity. AMP-activated protein kinase (AMPK) regulates glucose transport and ameliorates insulin resistance. The aim of the present study was to investigate whether activation of AMPK is involved in the mechanism by which deAND ameliorates insulin resistance in muscles. deAND amounts up to 40 [Formula: see text]M dose-dependently activated phosphorylation of AMPK[Formula: see text] and TBC1D1 in C2C12 myotubes. In addition, deAND significantly activated phosphorylation of LKB1 at 6 h after treatment, and this activation was maintained up to 48 h. deAND increased glucose uptake at 18 h after treatment, and this increase was time dependent up to 72 h. Compound C, an inhibitor of AMPK, suppressed deAND-induced phosphorylation of AMPK[Formula: see text] and TBC1D1 and reversed the effect on glucose uptake. In addition, the expression of GLUT4 mRNA and protein in C2C12 myotubes was up-regulated by deAND in a time-dependent manner. Promotion of GLUT4 gene transcription was verified by a pGL3-GLUT4 (837 bp) reporter assay. deAND also increased the nuclear translocation of MEF-2A and PPAR[Formula: see text]. After 16 weeks of feeding, the high-fat diet (HFD) inhibited phosphorylation of AMPK[Formula: see text] and TBC1D1 in skeletal muscle of obese C57BL/6JNarl mice, and deactivation of AMPK[Formula: see text] and TBC1D1 by the HFD was abolished by deAND supplementation. Supplementation with deAND significantly promoted membrane translocation of GLUT4 compared with the HFD group. Supplementation also significantly increased GLUT4 mRNA and protein expression in skeletal muscle compared with the HFD group. The hypoglycemic effects of deAND are likely associated with activation of the LKB1/AMPK[Formula: see text]/TBC1D1/GLUT4 signaling pathway and stimulation of MEF-2A- and PPAR[Formula: see text]-dependent GLUT4 gene expression, which account for the glucose uptake into skeletal muscle and lower blood glucose levels.

scholarly journals TWIST1 and TWIST2 regulate glycogen storage and inflammatory genes in skeletal muscle

2015 ◽  
Vol 224 (3) ◽  
pp. 303-313 ◽  
Author(s):  
Jonathan M Mudry ◽  
Julie Massart ◽  
Ferenc L M Szekeres ◽  
Anna Krook
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Diseases ◽  
Glycogen Synthesis ◽  
C2c12 Cells ◽  
Acid Oxidation ◽  
Diabetic Patients ◽  
Mrna Levels ◽  
Intact Mouse ◽  
Mouse Muscle ◽  
The Impact

TWIST proteins are important for development of embryonic skeletal muscle and play a role in the metabolism of tumor and white adipose tissue. The impact of TWIST on metabolism in skeletal muscle is incompletely studied. Our aim was to assess the impact of TWIST1 and TWIST2 overexpression on glucose and lipid metabolism. In intact mouse muscle, overexpression of Twist reduced total glycogen content without altering glucose uptake. Expression of TWIST1 or TWIST2 reducedPdk4mRNA, while increasing mRNA levels ofIl6,Tnfα, andIl1β. Phosphorylation of AKT was increased and protein abundance of acetyl CoA carboxylase (ACC) was decreased in skeletal muscle overexpressing TWIST1 or TWIST2. Glycogen synthesis and fatty acid oxidation remained stable in C2C12 cells overexpressing TWIST1 or TWIST2. Finally, skeletal muscle mRNA levels remain unaltered inob/obmice, type 2 diabetic patients, or in healthy subjects before and after 3 months of exercise training. Collectively, our results indicate that TWIST1 and TWIST2 are expressed in skeletal muscle. Overexpression of these proteins impacts proteins in metabolic pathways and mRNA level of cytokines. However, skeletal muscle levels of TWIST transcripts are unaltered in metabolic diseases.

scholarly journals Substrate oxidation in primary human skeletal muscle cells is influenced by donor age

2020 ◽  
Vol 382 (3) ◽  
pp. 599-608
Author(s):  
Vigdis Aas ◽  
G. Hege Thoresen ◽  
Arild C. Rustan ◽  
Jenny Lund
Keyword(s):  
Skeletal Muscle ◽  
Oleic Acid ◽  
Energy Metabolism ◽  
Substrate Oxidation ◽  
Pyruvate Dehydrogenase Kinase ◽  
Acid Oxidation ◽  
Acid Uptake ◽  
Donor Age ◽  
Human Myotubes ◽  
Human Skeletal Muscle Cells

AbstractPrimary human myotubes represent an alternative system to intact skeletal muscle for the study of human diseases related to changes in muscle energy metabolism. This work aimed to study if fatty acid and glucose metabolism in human myotubes in vitro were related to muscle of origin, donor gender, age, or body mass index (BMI). Myotubes from a total of 82 donors were established from three different skeletal muscles, i.e., musculus vastus lateralis, musculus obliquus internus abdominis, and musculi interspinales, and cellular energy metabolism was evaluated. Multiple linear regression analyses showed that donor age had a significant effect on glucose and oleic acid oxidation after correcting for gender, BMI, and muscle of origin. Donor BMI was the only significant contributor to cellular oleic acid uptake, whereas cellular glucose uptake did not rely on any of the variables examined. Despite the effect of age on substrate oxidation, cellular mRNA expression of pyruvate dehydrogenase kinase 4 (PDK4) and peroxisome proliferator–activated receptor gamma coactivator 1 alpha (PPARGC1A) did not correlate with donor age. In conclusion, donor age significantly impacts substrate oxidation in cultured human myotubes, whereas donor BMI affects cellular oleic acid uptake.

Persistent increase in glucose uptake by rat skeletal muscle following exercise

1981 ◽  
Vol 241 (5) ◽  
pp. C200-C203 ◽  
Author(s):  
J. L. Ivy ◽  
J. O. Holloszy
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Glycogen ◽  
Glycogen Synthesis ◽  
Exercise Stress ◽  
Rat Skeletal Muscle ◽  
Major Pathway ◽  
Glycogen Accumulation ◽  
Hindlimb Muscles ◽  
Muscle Glycogen Concentration

The effect of a bout of exercise on glucose uptake and glycogen synthesis in skeletal muscle was examined using a perfused rat hindlimb preparation. Rats were subjected to a bout of swimming. The exercise stress was moderate as reflected in a reduction of muscle glycogen concentration of only 50%. Glucose uptake and glycogen synthesis were measured in perfused hindlimb muscles for a 30-min period beginning approximately 60 min following the exercise. The rate of glucose uptake in the absence of insulin was 10-fold higher in hindlimbs of exercised animals than in the controls. The rate of glucose uptake was also higher in exercised than in control muscles in the presence of 50 microunits/ml or 10 mU/ml of insulin, but these differences were smaller than that found in the absence of insulin. Conversion to glycogen was the major pathway for disposal of the glucose taken up by muscle. The rate of glycogen accumulation in the exercised plantaris muscles was greater than in the control muscles both in the absence and presence of insulin.

scholarly journals An AMPK/Axin1-Rac1 signaling pathway mediates contraction-regulated glucose uptake in skeletal muscle cells

2020 ◽  
Vol 318 (3) ◽  
pp. E330-E342 ◽  
Author(s):  
Yingying Yue ◽  
Chang Zhang ◽  
Xuejiao Zhang ◽  
Shitian Zhang ◽  
Qian Liu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Signaling Pathway ◽  
Gastrocnemius Muscle ◽  
C2c12 Myotubes ◽  
Dependent Manner ◽  
Mouse Muscle ◽  
Protein Levels ◽  
Compound C ◽  
Skeletal Muscle Glucose Uptake

Contraction stimulates skeletal muscle glucose uptake predominantly through activation of AMP-activated protein kinase (AMPK) and Rac1. However, the molecular details of how contraction activates these signaling proteins are not clear. Recently, Axin1 has been shown to form a complex with AMPK and liver kinase B1 during glucose starvation-dependent activation of AMPK. Here, we demonstrate that electrical pulse-stimulated (EPS) contraction of C2C12 myotubes or treadmill exercise of C57BL/6 mice enhanced reciprocal coimmunoprecipitation of Axin1 and AMPK from myotube lysates or gastrocnemius muscle tissue. Interestingly, EPS or exercise upregulated total cellular Axin1 levels in an AMPK-dependent manner in C2C12 myotubes and gastrocnemius mouse muscle, respectively. Also, direct activation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleotide treatment of C2C12 myotubes or gastrocnemius muscle elevated Axin1 protein levels. On the other hand, siRNA-mediated Axin1 knockdown lessened activation of AMPK in contracted myotubes. Further, AMPK inhibition with compound C or siRNA-mediated knockdown of AMPK or Axin1 blocked contraction-induced GTP loading of Rac1, p21-activated kinase phosphorylation, and contraction-stimulated glucose uptake. In summary, our results suggest that an AMPK/Axin1-Rac1 signaling pathway mediates contraction-stimulated skeletal muscle glucose uptake.

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