scholarly journals Moringa oleifera Leaf Extract Upregulates Nrf2/HO-1 Expression and Ameliorates Redox Status in C2C12 Skeletal Muscle Cells

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5041
Author(s):  
Guglielmo Duranti ◽  
Mariateresa Maldini ◽  
Domenico Crognale ◽  
Katy Horner ◽  
Ivan Dimauro ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Enzyme Activities ◽  
Leaf Extract ◽  
Moringa Oleifera ◽  
Redox Homeostasis ◽  
Muscle Cells ◽  
Redox Status ◽  
Skeletal Muscle Cells ◽  
Heme Oxygenase 1 ◽  
Dependent Manner

Moringa oleifera is a multi-purpose herbal plant with numerous health benefits. In skeletal muscle cells, Moringa oleifera leaf extract (MOLE) acts by increasing the oxidative metabolism through the SIRT1-PPARα pathway. SIRT1, besides being a critical energy sensor, is involved in the activation related to redox homeostasis of transcription factors such as the nuclear factor erythroid 2-related factor (Nrf2). The aim of the present study was to evaluate in vitro the capacity of MOLE to influence the redox status in C2C12 myotubes through the modulation of the total antioxidant capacity (TAC), glutathione levels, Nrf2 and its target gene heme oxygenase-1 (HO-1) expression, as well as enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and transferase (GST). Moreover, the impact of MOLE supplementation on lipid peroxidation and oxidative damage (i.e., TBARS and protein carbonyls) was evaluated. Our results highlight for the first time that MOLE increased not only Nrf2 and HO-1 protein levels in a dose-dependent manner, but also improved glutathione redox homeostasis and the enzyme activities of CAT, SOD, GPx and GST. Therefore, it is intriguing to speculate that MOLE supplementation could represent a valuable nutrition for the health of skeletal muscles.

scholarly journals Suppression of Pyruvate Dehydrogenase Kinase by Dichloroacetate in Cancer and Skeletal Muscle Cells Is Isoform Specific and Partially Independent of HIF-1α

2021 ◽  
Vol 22 (16) ◽  
pp. 8610
Author(s):  
Nives Škorja Milić ◽  
Klemen Dolinar ◽  
Katarina Miš ◽  
Urška Matkovič ◽  
Maruša Bizjak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cancer Cells ◽  
Pyruvate Dehydrogenase ◽  
Hypoxia Inducible Factor ◽  
Muscle Cells ◽  
Pyruvate Dehydrogenase Kinase ◽  
Skeletal Muscle Cells ◽  
Dependent Manner ◽  
Protein Levels ◽  
L6 Myotubes

Inhibition of pyruvate dehydrogenase kinase (PDK) emerged as a potential strategy for treatment of cancer and metabolic disorders. Dichloroacetate (DCA), a prototypical PDK inhibitor, reduces the abundance of some PDK isoenzymes. However, the underlying mechanisms are not fully characterized and may differ across cell types. We determined that DCA reduced the abundance of PDK1 in breast (MDA-MB-231) and prostate (PC-3) cancer cells, while it suppressed both PDK1 and PDK2 in skeletal muscle cells (L6 myotubes). The DCA-induced PDK1 suppression was partially dependent on hypoxia-inducible factor-1α (HIF-1α), a transcriptional regulator of PDK1, in cancer cells but not in L6 myotubes. However, the DCA-induced alterations in the mRNA and the protein levels of PDK1 and/or PDK2 did not always occur in parallel, implicating a role for post-transcriptional mechanisms. DCA did not inhibit the mTOR signaling, while inhibitors of the proteasome or gene silencing of mitochondrial proteases CLPP and AFG3L2 did not prevent the DCA-induced reduction of the PDK1 protein levels. Collectively, our results suggest that DCA reduces the abundance of PDK in an isoform-dependent manner via transcriptional and post-transcriptional mechanisms. Differential response of PDK isoenzymes to DCA might be important for its pharmacological effects in different types of cells.

scholarly journals Actions of 1,25(OH)2-vitamin D3 on the cellular cycle depend on VDR and p38 MAPK in skeletal muscle cells

2014 ◽  
Vol 53 (3) ◽  
pp. 331-343 ◽  
Author(s):  
Ana P Irazoqui ◽  
Ricardo L Boland ◽  
Claudia G Buitrago
Keyword(s):  
Skeletal Muscle ◽  
Vitamin D ◽  
P38 Mapk ◽  
Muscle Cells ◽  
C2c12 Cells ◽  
Skeletal Muscle Cells ◽  
Cyclin D3 ◽  
C2c12 Myoblast ◽  
G1 Arrest ◽  
Dependent Manner

Previously, we have reported that 1,25(OH)2-vitamin D3(1,25D) activates p38 MAPK (p38) in a vitamin D receptor (VDR)-dependent manner in proliferative C2C12 myoblast cells. It was also demonstrated that 1,25D promotes muscle cell proliferation and differentiation. However, we did not study these hormone actions in depth. In this study we have investigated whether the VDR and p38 participate in the signaling mechanism triggered by 1,25D. In C2C12 cells, the VDR was knocked down by a shRNA, and p38 was specifically inhibited using SB-203580. Results from cell cycle studies indicated that hormone stimulation prompts a peak of S-phase followed by an arrest in the G0/G1-phase, events which were dependent on VDR and p38. Moreover, 1,25D increases the expression of cyclin D3 and the cyclin-dependent kinase inhibitors, p21Waf1/Cip1and p27Kip1, while cyclin D1 protein levels did not change during G0/G1 arrest. In all these events, p38 and VDR were required. At the same time, a 1,25D-dependent acute increase in myogenin expression was observed, indicating that the G0/G1 arrest of cells is a pro-differentiative event. Immunocytochemical assays revealed co-localization of VDR and cyclin D3, promoted by 1,25D in a p38-dependent manner. When cyclin D3 expression was silenced, VDR and myogenin levels were downregulated, indicating that cyclin D3 was required for 1,25D-induced VDR expression and the concomitant entrance into the differentiation process. In conclusion, the VDR and p38 are involved in control of the cellular cycle by 1,25D in skeletal muscle cells, providing key information on the mechanisms underlying hormone regulation of myogenesis.

scholarly journals 1-Deoxysphingolipids, Early Predictors of Type 2 Diabetes, Compromise the Functionality of Skeletal Myoblasts

2021 ◽  
Vol 12 ◽  
Author(s):  
Duyen Tran ◽  
Stephen Myers ◽  
Courtney McGowan ◽  
Darren Henstridge ◽  
Rajaraman Eri ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Muscle Dysfunction ◽  
Dependent Manner

Metabolic dysfunction, dysregulated differentiation, and atrophy of skeletal muscle occur as part of a cluster of abnormalities associated with the development of Type 2 diabetes mellitus (T2DM). Recent interest has turned to the attention of the role of 1-deoxysphingolipids (1-DSL), atypical class of sphingolipids which are found significantly elevated in patients diagnosed with T2DM but also in the asymptomatic population who later develop T2DM. In vitro studies demonstrated that 1-DSL have cytotoxic properties and compromise the secretion of insulin from pancreatic beta cells. However, the role of 1-DSL on the functionality of skeletal muscle cells in the pathophysiology of T2DM still remains unclear. This study aimed to investigate whether 1-DSL are cytotoxic and disrupt the cellular processes of skeletal muscle precursors (myoblasts) and differentiated cells (myotubes) by performing a battery of in vitro assays including cell viability adenosine triphosphate assay, migration assay, myoblast fusion assay, glucose uptake assay, and immunocytochemistry. Our results demonstrated that 1-DSL significantly reduced the viability of myoblasts in a concentration and time-dependent manner, and induced apoptosis as well as cellular necrosis. Importantly, myoblasts were more sensitive to the cytotoxic effects induced by 1-DSL rather than by saturated fatty acids, such as palmitate, which are critical mediators of skeletal muscle dysfunction in T2DM. Additionally, 1-DSL significantly reduced the migration ability of myoblasts and the differentiation process of myoblasts into myotubes. 1-DSL also triggered autophagy in myoblasts and significantly reduced insulin-stimulated glucose uptake in myotubes. These findings demonstrate that 1-DSL directly compromise the functionality of skeletal muscle cells and suggest that increased levels of 1-DSL observed during the development of T2DM are likely to contribute to the pathophysiology of muscle dysfunction detected in this disease.

A Novel Partial PPARγ Agonist Has Weaker Lipogenic Effect in Adipocytes and Stimulates GLUT4 Translocation in Skeletal Muscle Cells via AMPK-Dependent Signaling

Pharmacology ◽  
2021 ◽  
pp. 1-12
Author(s):  
Bhavimani Guru ◽  
Akhilesh K. Tamrakar ◽  
Subhankar P. Mandal ◽  
Prashantha B.R. Kumar ◽  
Aditya Sharma ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Molecular Docking ◽  
Md Simulation ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Dependent Manner ◽  
Glut4 Translocation ◽  
Binding Interactions ◽  
Pparγ Agonists

<b><i>Introduction:</i></b> Peroxisome proliferator-activated receptor gamma (PPARγ) agonists are highly effective in treating insulin resistance. However, associated side effects such as weight gain due to increase in adipogenesis and lipogenesis hinder their clinical use. The aim of the study was to design and synthesize novel partial PPARγ agonists with weaker lipogenic effect in adipocytes and enhanced glucose transporter 4 (GLUT4) translocation stimulatory effect in skeletal muscle cells. <b><i>Methods:</i></b> Novel partial PPARγ agonists (GS1, GS2, and GS3) were designed and screened to predict their binding interactions with PPARγ by molecular docking. The stability of the docked ligand-PPARγ complex was studied by molecular dynamics (MD) simulation. The cytotoxicity of synthesized compounds was tested in 3T3-L1 adipocytes and L6 myoblasts by MTT assay. The lipogenic effect was investigated in 3T3-L1 adipocytes using oil red O staining and GLUT4 translocation stimulatory effect in L6-GLUT4<i>myc</i> myotubes by an antibody-coupled colorimetric assay. <b><i>Results:</i></b> The molecular docking showed the binding interactions between designed agonists and PPARγ. MD simulation demonstrated good stability between the GS2-PPARγ complex. GS2 and GS3 did not show any significant effect on cell viability up to 80 or 100 μM concentration. Pioglitazone treatment significantly increased intracellular lipid accumulation in adipocytes compared to control. However, this effect was significantly less in GS2- and GS3-treated conditions compared to pioglitazone at 10 μM concentration, indicating weaker lipogenic effect. Furthermore, GS2 significantly stimulated GLUT4 translocation to the plasma membrane in a dose-dependent manner via the AMPK-dependent signaling pathway in skeletal muscle cells. <b><i>Conclusion:</i></b> GS2 may be a promising therapeutic agent for the treatment of insulin resistance and type 2 diabetes mellitus without adiposity.

Genetic downregulation of AMPK-α isoforms uncovers the mechanism by which metformin decreases FA uptake and oxidation in skeletal muscle cells

2010 ◽  
Vol 299 (6) ◽  
pp. C1549-C1561 ◽  
Author(s):  
Lindsey D. Bogachus ◽  
Lorraine P. Turcotte
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Metabolism ◽  
Muscle Cells ◽  
Time Dependent ◽  
Skeletal Muscle Cells ◽  
Dependent Manner ◽  
Ampk Activity ◽  
Palmitate Uptake ◽  
Amp Activated Protein Kinase

Metformin is known to improve insulin sensitivity in part via a rise in AMP-activated protein kinase (AMPK) activity and alterations in muscle metabolism. However, a full understanding of how metformin alters AMPK-α1 vs. AMPK-α2 activation remains unknown. To study this question, L6 skeletal muscle cells were treated with or without RNAi oligonucleotide sequences to downregulate AMPK-α1 or AMPK-α2 protein expression and incubated with or without 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) or metformin and/or insulin. In contrast to AICAR, which preferentially activated AMPK-α2, metformin preferentially activated AMPK-α1 in a dose- and time-dependent manner. Metformin increased ( P < 0.05) glucose uptake and plasma membrane (PM) Glut4 in a dose- and time-dependent manner. Metformin significantly reduced palmitate uptake ( P < 0.05) and oxidation ( P < 0.05), and this was accompanied by a similar decrease ( P < 0.05) in PM CD36 content but with no change in acetyl-CoA carboxylase (ACC) phosphorylation ( P > 0.05). AICAR and metformin similarly increased ( P < 0.05) nuclear silent mating-type information regulator 2 homolog 1 (SIRT1) activity. Downregulation of AMPK-α1 completely prevented the metformin-induced reduction in palmitate uptake and oxidation but only partially reduced the metformin-induced increase in glucose uptake. Downregulation of AMPK-α2 had no effect on metformin-induced glucose uptake, palmitate uptake, and oxidation. The increase in SIRT1 activity induced by metformin was not affected by downregulation of either AMPK-α1 or AMPK-α2. Our data indicate that, in muscle cells, the inhibitory effects of metformin on fatty acid metabolism occur via preferential phosphorylation of AMPK-α1, and the data indicate that cross talk between AMPK and SIRT1 does not favor either AMPK isozyme.

scholarly journals 6-Mercaptopurine augments glucose transport activity in skeletal muscle cells in part via a mechanism dependent upon orphan nuclear receptor NR4A3

2013 ◽  
Vol 305 (9) ◽  
pp. E1081-E1092 ◽  
Author(s):  
Qinglan Liu ◽  
Xiaolin Zhu ◽  
Lusheng Xu ◽  
Yuchang Fu ◽  
W. Timothy Garvey
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Nuclear Receptor ◽  
Inflammatory Diseases ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Target Cells ◽  
Dependent Manner ◽  
Orphan Nuclear Receptor ◽  
Transport Activity

The purine anti-metabolite 6-mercaptopurine (6-MP) is widely used for the treatment of leukemia and inflammatory diseases. The cellular effects of 6-MP on metabolism remain unknown; however, 6-MP was recently found to activate the orphan nuclear receptor NR4A3 in skeletal muscle cell lines. We have reported previously that NR4A3 (also known as NOR-1, MINOR) is a positive regulator of insulin sensitivity in adipocytes. To further explore the role of NR4A3 activation in insulin action, we explored whether 6-MP activation of NR4A3 could modulate glucose transport system activity in L6 skeletal muscle cells. We found that 6-MP increased both NR4A3 expression and NR4A3 transcriptional activity and enhanced glucose transport activity via increasing GLUT4 translocation in both basal and insulin-stimulated L6 cells in an NR4A3-dependent manner. Furthermore, 6-MP increased levels of phospho-AS160, although this effect was not modulated by NR4A3 overexpression or knockdown. These primary findings provide a novel proof of principle that 6-MP, a small molecule NR4A3 agonist, can augment glucose uptake in insulin target cells, although this occurs via both NR4A3-dependent and -independent actions; the latter is related to an increase in phospho-AS160. These results establish a novel target for development of new treatments for insulin resistance.

scholarly journals Heat induces interleukin-6 in skeletal muscle cells via TRPV1/PKC/CREB pathways

2017 ◽  
Vol 122 (3) ◽  
pp. 683-694 ◽  
Author(s):  
Syotaro Obi ◽  
Toshiaki Nakajima ◽  
Takaaki Hasegawa ◽  
Hironobu Kikuchi ◽  
Gaku Oguri ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Intracellular Calcium ◽  
Interleukin 6 ◽  
Transient Receptor Potential ◽  
Signal Transduction Pathway ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Calcium Flux ◽  
Dependent Manner ◽  
Intracellular Calcium Flux

Interleukin-6 (IL-6) is released from skeletal muscle cells and induced by exercise, heat, catecholamine, glucose, lipopolysaccharide, reactive oxygen species, and inflammation. However, the mechanism that induces release of IL-6 from skeletal muscle cells remains unknown. Thermosensitive transient receptor potential (TRP) proteins such as TRPV1–4 play vital roles in cellular functions. In this study we hypothesized that TRPV1 senses heat, transmits a signal into the nucleus, and produces IL-6. The purpose of the present study is to investigate the underlying mechanisms whereby skeletal muscle cells sense and respond to heat. When mouse myoblast cells were exposed to 37–42°C for 2 h, mRNA expression of IL-6 increased in a temperature-dependent manner. Heat also increased IL-6 secretion in myoblast cells. A fura 2 fluorescence dual-wavelength excitation method showed that heat increased intracellular calcium flux in a temperature-dependent manner. Intracellular calcium flux and IL-6 mRNA expression were increased by the TRPV1 agonists capsaicin and N-arachidonoyldopamine and decreased by the TRPV1 antagonists AMG9810 and SB366791 and siRNA-mediated knockdown of TRPV1. TRPV2, 3, and 4 agonists did not change intracellular calcium flux. Western blotting with inhibitors demonstrated that heat increased phosphorylation levels of TRPV1, followed by PKC and cAMP response element-binding protein (CREB). PKC inhibitors, Gö6983 and staurosporine, CREB inhibitors, curcumin and naphthol AS-E, and knockdown of CREB suppressed the heat-induced increases in IL-6. These results indicate that heat increases IL-6 in skeletal muscle cells through the TRPV1, PKC, and CREB signal transduction pathway.NEW & NOTEWORTHY Heat increases the release of interleukin-6 (IL-6) from skeletal muscle cells. IL-6 has been shown to serve immune responses and metabolic functions in muscle. It can be anti-inflammatory as well as proinflammatory. However, the mechanism that induces release of IL-6 from skeletal muscle cells remains unknown. Here we show that heat increases IL-6 in skeletal muscle cells through the transient receptor potential vannilloid 1, PKC, and cAMP response element-binding protein signal transduction pathway.

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