DHA/EPA Improves GLUT4 Translocation, Glycogen Synthesis and Aerobic Glycolysis in Skeletal Muscle of db/db Mice

Abstract Objectives The aim of this study was to investigate the effects of DHA and EPA on glucose metabolism including glucose uptake and disposal in skeletal muscle and C2C12 myotubes. Methods Four-week-old db/db diabetic mice were fed with control diet enriched with DHA/EPA (purity > 99%, 1% wt/wt) for 10 weeks. To further explore the underlying mechanism, C2C12 myotubes were induced insulin resistance by palmitate and treated with 25 and 50 μM DHA/EPA for 24 h after differentiation. Results The untargeted metabolome of skeletal muscle showed BCAAs and other metabolites associated with glycolysis and TCA cycle were altered by DHA/EPA treatment. Further detections revealed DHA/EPA treatment promoted the translocation of GLUT4 via increasing Rab8a and SNAP23 expression, and enhanced the activity of GS and PDH. In vitro, the glucose consumption was improved coupled with promoted Rab8a or SNAP23, and GS and PDH were also activated under DHA/EPA intervention increased glucose consumption via promoted Rab8a and SNAP23. The GS and PDH were also activated, which were in line with the results in vivo. Conclusions Long-term intake of DHA and EPA may have a protective effect on diabetes through promoted GLUT4 translocation, glycogen synthesis and aerobic glycolysis in skeletal muscle. Funding Sources This work was supported by the National Natural Science Foundation of China (grant number 81773419 and 81300309), Chinese Institute of Nutrition DSM Research Fund (grant number CNS-DSM-2017–035), China National Program for Support of Top-notch Young Professionals and China Postdoctoral Science Foundation (grant number 2020M681869).

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FOXE1 represses cell proliferation and Warburg effect by inhibiting HK2 in colorectal cancer

Cell Communication and Signaling ◽

10.1186/s12964-019-0502-8 ◽

2020 ◽

Vol 18 (1) ◽

Cited By ~ 6

Author(s):

Weixing Dai ◽

Xianke Meng ◽

Shaobo Mo ◽

Wenqiang Xiang ◽

Ye Xu ◽

...

Keyword(s):

Colorectal Cancer ◽

Cell Proliferation ◽

Poor Prognosis ◽

Aerobic Glycolysis ◽

Lactate Production ◽

Glucose Consumption ◽

Underlying Mechanism ◽

Low Expression

Abstract Background Low expression of FOXE1, a member of Forkhead box (FOX) transcription factor family that plays vital roles in cancers, contributes to poor prognosis of colorectal cancer (CRC) patients. However, the underlying mechanism remains unclear. Materials and methods The effects of FOXE1 on the growth of colon cancer cells and the expression of glycolytic enzymes were investigated in vitro and in vivo. Molecular biological experiments were used to reveal the underlying mechanisms of altered aerobic glycolysis. CRC tissue specimens were used to determine the clinical association of ectopic metabolism caused by dysregulated FOXE1. Results FOXE1 is highly expressed in normal colon tissues compared with cancer tissues and low expression of FOXE1 is significantly associated with poor prognosis of CRC patients. Silencing FOXE1 in CRC cell lines dramatically enhanced cell proliferation and colony formation and promoted glucose consumption and lactate production, while enforced expression of FOXE1 manifested the opposite effects. Mechanistically, FOXE1 bound directly to the promoter region of HK2 and negatively regulated its transcription. Furthermore, the expression of FOXE1 in CRC tissues was negatively correlated with that of HK2. Conclusion FOXE1 functions as a critical tumor suppressor in regulating tumor growth and glycolysis via suppressing HK2 in CRC.

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Tumor Energy Metabolism and Potential of 3-Bromopyruvate as an Inhibitor of Aerobic Glycolysis: Implications in Tumor Treatment

Cancers ◽

10.3390/cancers11030317 ◽

2019 ◽

Vol 11 (3) ◽

pp. 317 ◽

Cited By ~ 22

Author(s):

Tengjiao Fan ◽

Guohui Sun ◽

Xiaodong Sun ◽

Lijiao Zhao ◽

Rugang Zhong ◽

...

Keyword(s):

Energy Metabolism ◽

Tumor Cells ◽

Cultured Cells ◽

Aerobic Glycolysis ◽

Underlying Mechanism ◽

Human Case ◽

Tumor Formation ◽

Antitumor Effects

Tumor formation and growth depend on various biological metabolism processes that are distinctly different with normal tissues. Abnormal energy metabolism is one of the typical characteristics of tumors. It has been proven that most tumor cells highly rely on aerobic glycolysis to obtain energy rather than mitochondrial oxidative phosphorylation (OXPHOS) even in the presence of oxygen, a phenomenon called “Warburg effect”. Thus, inhibition of aerobic glycolysis becomes an attractive strategy to specifically kill tumor cells, while normal cells remain unaffected. In recent years, a small molecule alkylating agent, 3-bromopyruvate (3-BrPA), being an effective glycolytic inhibitor, has shown great potential as a promising antitumor drug. Not only it targets glycolysis process, but also inhibits mitochondrial OXPHOS in tumor cells. Excellent antitumor effects of 3-BrPA were observed in cultured cells and tumor-bearing animal models. In this review, we described the energy metabolic pathways of tumor cells, mechanism of action and cellular targets of 3-BrPA, antitumor effects, and the underlying mechanism of 3-BrPA alone or in combination with other antitumor drugs (e.g., cisplatin, doxorubicin, daunorubicin, 5-fluorouracil, etc.) in vitro and in vivo. In addition, few human case studies of 3-BrPA were also involved. Finally, the novel chemotherapeutic strategies of 3-BrPA, including wafer, liposomal nanoparticle, aerosol, and conjugate formulations, were also discussed for future clinical application.

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Effects of prolonged elevation of plasma adrenaline concentration in vivo on insulin-sensitivity in soleus muscle of the rat

Biochemical Journal ◽

10.1042/bj2440655 ◽

1987 ◽

Vol 244 (3) ◽

pp. 655-660 ◽

Cited By ~ 20

Author(s):

L Budohoski ◽

R A Challiss ◽

A Dubaniewicz ◽

H Kaciuba-Usciłko ◽

B Leighton ◽

...

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Glucose Transport ◽

Soleus Muscle ◽

Glycogen Synthesis ◽

Biochemical Basis ◽

Plasma Adrenaline ◽

Skeletal Muscle Insulin Sensitivity

1. Prolonged elevation of the plasma adrenaline concentration was produced in rats by implantation of adrenaline-releasing retard-tablets. With this technique, a hyperadrenalinaemic state is maintained for at least 5 days. 2. At 6 h after implantation of the retard-tablet it was found that plasma glucose and fatty acid concentrations increased and insulin concentration decreased compared with values obtained from placebo-tablet-implanted rats. Administration of a subcutaneous glucose load demonstrated an impaired glucose tolerance in vivo, and incubation of soleus muscle strips from 6 h-hyperadrenalinaemic rats in vitro demonstrated a decreased sensitivity of the rates of glycolysis and glucose transport to insulin. 3. The sensitivities of the rates of glycolysis, glucose transport and glycogen synthesis to insulin were determined for the incubated soleus muscle preparation isolated from animals after 48 h, 72 h and 120 h duration of hyperadrenalinaemia. At 48 h after retard-tablet implantation, the sensitivity of the processes of glucose transport and glycolysis was decreased; at 72 h, the insulin-sensitivities of the rates of glycolysis and glucose transport in skeletal muscle were similar to those determined for control animals; at 120 h, however, the sensitivities of the processes of glucose transport and glycolysis were both statistically significantly increased. In contrast, no changes in the sensitivity of the process of glycogen synthesis were observed at any of the time intervals studied. 4. The possible biochemical basis for the observed changes in skeletal-muscle insulin-sensitivity with prolonged hyperadrenalinaemia is discussed.

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Trimetazidine Attenuates Dexamethasone-Induced Muscle Atrophy via Inhibiting NLRP3/GSDMD Pathway-Mediated Pyroptosis

10.20944/preprints202012.0643.v1 ◽

2020 ◽

Author(s):

Li Wang ◽

Ming-Qing He ◽

Xi-Yu Shen ◽

Kang-Zhen Zhang ◽

Can Zhao ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Atrophy ◽

Ring Finger ◽

Muscle Performance ◽

Skeletal Muscle Atrophy ◽

C2c12 Myotubes ◽

High Dose ◽

Therapeutic Compound

Skeletal muscle atrophy is one of the major side effects of high dose or sustained usage of glucocorticoids. Pyroptosis is a novel form of pro-inflammatory programmed cell death that may contribute to skeletal muscle injury. Trimetazidine, a well-known anti-anginal agent, can also improve skeletal muscle performance both in human and mice. We here showed that dexamethasone induced atrophy, evidenced by the increase of muscle atrophy F-box (Atrogin-1) and muscle ring finger 1 (MuRF1) expression , and the decrease of myotube diameter in C2C12 myotubes. Dexamethasone also induced pyroptosis, indicated by upregulated pyroptosis-related protein NLRP3, Caspase-1 and GSDMD. Knockdown of NLRP3 or GSDMD attenuated dexamethasone-induced myotube pyroptosis and atrophy. Trimetazidine administration ameliorated dexamethasone-induced muscle atrophy both in vivo and in vitro. Moreover, trimetazidine improved exercise tolerance, as evidenced by increased running distance and running time, as well as increased skeletal muscle mass in dexamethasone-treated mice. Mechanically, trimetazidine could reverse dexamethasone-induced activation of pyroptosis both in C2C12 myotubes and in mice. Taken together, our present study demonstrated that NLRP3/GSDMD pathway-mediated pyroptosis was involved in dexamethasone-induced skeletal muscle atrophy. Trimetazidine could partially alleviate dexamethasone-induced skeletal muscle atrophy, and increase the diameter of C2C12 myotubes via inhibiting pyroptosis. Thus, trimetazidine might be a potential therapeutic compound for the prevention of muscle atrophy in glucocorticoid-treated patients.

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Garcinol Promotes the Formation of Slow-Twitch Muscle Fibers by Inhibiting p300-Dependent Acetylation of PGC-1α

10.21203/rs.3.rs-1102585/v1 ◽

2021 ◽

Author(s):

Weilei Yao ◽

Baoyin Guo ◽

Zhengxi Bao ◽

Lu Huang ◽

Tongxin Wang ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Fiber ◽

Control Diet ◽

Skeletal Muscle Fiber ◽

C2c12 Myotubes ◽

Slow Twitch ◽

Slow Myhc ◽

Myhc Expression ◽

Fast Myhc

Abstract Background The conversion of skeletal muscle fiber from fast twitch to slow-twitch is crucial for sustained contractile and stretchable events, energy homeostasis, and anti-fatigue ability. The purpose of our study was to explore the mechanism and effects of garcinol on the regulation of skeletal muscle fiber type transformation. Methods Forty 21-day-old male C57/BL6J mice (n = 10/diet) were fed a control diet or a control diet plus garcinol at 100 mg/kg (Low Gar), 300 mg/kg (Mid Gar), or 500 mg/kg (High Gar) for 12 weeks. The tibialis anterior (TA) and soleus muscles were collected for protein and immunoprecipitation analyses. Results Dietary garcinol significantly downregulated (P<0.05) fast MyHC expression and upregulated (P<0.05) slow MyHC expression in the TA and soleus muscles. Garcinol significantly increased (P<0.05) the activity of PGC-1α and markedly decreased (P<0.05) the acetylation of PGC-1α. In vitro and in vivo experiments showed that garcinol decreased (P<0.05) lactate dehydrogenase activity and increased (P<0.05) the activities of malate dehydrogenase and succinic dehydrogenase. In addition, the results of immunostaining C2C12 myotubes showed that garcinol treatment increased (P<0.05) the transformation of glycolytic muscle fiber to oxidative muscle fiber by 45.9%. Garcinol treatment and p300 interference reduced (P<0.05) the expression of fast MyHC but increased (P<0.05) the expression of slow MyHC in vitro. Moreover, the acetylation of PGC-1α was significantly decreased (P<0.05). Conclusion Garcinol promotes the transformation of skeletal muscle fibers from the fast-glycolytic type to the slow-oxidative type through the p300/PGC-1α signaling pathway in C2C12 myotubes.

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Physiological glucocorticoid levels regulate glutamine and insulin-mediated glucose metabolism in skeletal muscle of the rat. Studies with RU 486 (mifepristone)

Biochemical Journal ◽

10.1042/bj2740187 ◽

1991 ◽

Vol 274 (1) ◽

pp. 187-192 ◽

Cited By ~ 11

Author(s):

B Leighton ◽

M Parry-Billings ◽

G Dimitriadis ◽

J Bond ◽

E A Newsholme ◽

...

Keyword(s):

Skeletal Muscle ◽

Soleus Muscle ◽

Plasma Glucose ◽

Dark Period ◽

Feeding Activity ◽

Glycogen Synthesis ◽

Glutamine Metabolism ◽

Ru 486

This study examined the effects of antagonism of the peak level of glucocorticoids in vivo, which occurs as rats enter the feeding/activity (dark) period on glucose and glutamine metabolism in incubated isolated rat soleus muscle preparations. Thus the rats were treated with the potent glucocorticoid antagonist RU 486 2 h before and 1 and 2 h into the dark period. Both the content of glutamine in skeletal muscle in vivo and plasma glucose and glutamine concentrations were elevated midway through the dark period, compared with the beginning of the period. RU 486 prevented the increases in plasma glucose and glutamine and caused a significant decrease in both the rate of release of glutamine in soleus muscle in vitro and the content of glutamine in gastrocnemius muscle. The sensitivity of soleus muscle to insulin in vitro is markedly decreased when isolated midway through the dark period (i.e. at 03:00 h) [Leighton, Kowalchuk, Challiss & Newsholme (1988) Am. J. Physiol. 255, E41-E45]. We now show that the concentrations of insulin required to stimulate lactate formation and glycogen synthesis half-maximally were 95 and 250 muunits/ml respectively, and treatment of rats with RU 486 decreased these values to 55 and 90 muunits of insulin/ml respectively. Thus antagonism of the action of the normal circadian rise in the level of glucocorticoids in rats reverses insulin insensitivity in soleus muscles in vitro.

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A Fish-Derived Protein Hydrolysate Induces Postprandial Aminoacidaemia and Skeletal Muscle Anabolism in an In Vitro Cell Model Using Ex Vivo Human Serum

Nutrients ◽

10.3390/nu13020647 ◽

2021 ◽

Vol 13 (2) ◽

pp. 647

Author(s):

Matthew J. Lees ◽

David Nolan ◽

Miryam Amigo-Benavent ◽

Conor J. Raleigh ◽

Neda Khatib ◽

...

Keyword(s):

Older Adults ◽

Skeletal Muscle ◽

Human Serum ◽

Body Mass ◽

Ex Vivo ◽

Protein Hydrolysate ◽

C2c12 Myotubes ◽

The Impact

Fish-derived proteins, particularly fish protein hydrolysates (FPH), offer potential as high-quality sources of dietary protein, whilst enhancing economic and environmental sustainability. This study investigated the impact of a blue whiting-derived protein hydrolysate (BWPH) on aminoacidaemia in vivo and skeletal muscle anabolism in vitro compared with whey protein isolate (WPI) and an isonitrogenous, non-essential amino acid (NEAA) control (0.33 g·kg−1·body mass−1) in an ex vivo, in vitro experimental design. Blood was obtained from seven healthy older adults (two males, five females; age: 72 ± 5 years, body mass index: 24.9 ± 1.6 kg·m2) in three separate trials in a randomised, counterbalanced, double-blind design. C2C12 myotubes were treated with ex vivo human serum-conditioned media (20%) for 4 h. Anabolic signalling (phosphorylation of mTOR, p70S6K, and 4E-BP1) and puromycin incorporation were determined by immunoblotting. Although BWPH and WPI both induced postprandial essential aminoacidaemia in older adults above the NEAA control, peak and area under the curve (AUC) leucine and essential amino acids were more pronounced following WPI ingestion. Insulin was elevated above baseline in WPI and BWPH only, a finding reinforced by higher peak and AUC values compared with NEAA. Muscle protein synthesis, as measured by puromycin incorporation, was greater after incubation with WPI-fed serum compared with fasted serum (P = 0.042), and delta change was greater in WPI (P = 0.028) and BWPH (P = 0.030) compared with NEAA. Myotube hypertrophy was greater in WPI and BWPH compared with NEAA (both P = 0.045), but was similar between bioactive conditions (P = 0.853). Taken together, these preliminary findings demonstrate the anabolic potential of BWPH in vivo and ex vivo, thus providing justification for larger studies in older adults using gold-standard measures of acute and chronic MPS in vivo.

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Prion Infection of Muscle Cells In Vitro

Journal of Virology ◽

10.1128/jvi.02628-06 ◽

2007 ◽

Vol 81 (9) ◽

pp. 4615-4624 ◽

Cited By ~ 21

Author(s):

Wendy M. Dlakic ◽

Eric Grigg ◽

Richard A. Bessen

Keyword(s):

Skeletal Muscle ◽

Cell Line ◽

Muscle Cells ◽

C2c12 Cells ◽

C2c12 Myotubes ◽

C2c12 Myoblasts ◽

Peripheral Cell ◽

Prion Infection

ABSTRACT The prion agent has been detected in skeletal muscle of humans and animals with prion diseases. Here we report scrapie infection of murine C2C12 myoblasts and myotubes in vitro following coculture with a scrapie-infected murine neuroblastoma (N2A) cell line but not following incubation with a scrapie-infected nonneuronal cell line or a scrapie brain homogenate. Terminal differentiation of scrapie-infected C2C12 myoblasts into myotubes resulted in an increase in the expression of the disease-specific prion protein, PrPSc. The amount of scrapie infectivity or PrPSc in C2C12 myotubes was comparable to the levels found in scrapie-infected N2A cells, indicating that a high level of infection was established in muscle cells. Subclones of scrapie-infected C2C12 cells produced high levels of PrPSc in myotubes, and the C-terminal C2 polypeptide fragment of PrPSc was found based on deglycosylation and PrPSc-specific immunoprecipitation of cell lysates. This is the first report of a stable prion infection in muscle cells in vitro and of a long-term prion infection in a nondividing, differentiated peripheral cell type in culture. These in vitro studies also suggest that in vivo prion infection of skeletal muscle requires contact with prion-infected neurons or, possibly, nerve terminals.

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Human engineered skeletal muscle of hypaxial origin from pluripotent stem cells with advanced function and regenerative capacity

10.1101/2021.07.12.452030 ◽

2021 ◽

Author(s):

Mina Shahriyari ◽

Md Islam ◽

M Sakib ◽

Anastasia Rika ◽

Dennis Krueger ◽

...

Keyword(s):

Skeletal Muscle ◽

Stem Cells ◽

Satellite Cell ◽

Pluripotent Stem Cells ◽

Cell Activation ◽

Muscle Development ◽

Underlying Mechanism ◽

Hypaxial Muscle

Human pluripotent stem cell derived muscle models show great potential for translational research. Here, we describe developmentally inspired methods for derivation of skeletal muscle cells and their utility in three-dimensional skeletal muscle organoid formation as well as skeletal muscle tissue engineering. Key steps include the directed differentiation of human pluripotent stem cells to embryonic muscle progenitors of hypaxial origin followed by primary and secondary fetal myogenesis into hypaxial muscle with development of a satellite cell pool and evidence for innervation in vitro. Skeletal muscle organoids faithfully recapitulate all steps of embryonic myogenesis in 3D. Tissue engineered muscle exhibits organotypic maturation and function, advanced by thyroid hormone. Regenerative competence was demonstrated in a cardiotoxin injury model with evidence of satellite cell activation as underlying mechanism. Collectively, we introduce a hypaxial muscle model with canonical properties of bona fide skeletal muscle in vivo to study muscle development, maturation, disease, and repair.

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Neuregulin 1 Drives Morphological and Phenotypical Changes in C2C12 Myotubes: Towards De Novo Formation of Intrafusal Fibres In Vitro

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.760260 ◽

2022 ◽

Vol 9 ◽

Author(s):

Philip Barrett ◽

Tom J. Quick ◽

Vivek Mudera ◽

Darren J. Player

Keyword(s):

Skeletal Muscle ◽

Muscle Spindle ◽

De Novo ◽

C2c12 Myotubes ◽

Muscle Fibres ◽

Neuregulin 1 ◽

Gene And Protein Expression ◽

Intrafusal Fibres

Muscle spindles are sensory organs that detect and mediate both static and dynamic muscle stretch and monitor muscle position, through a specialised cell population, termed intrafusal fibres. It is these fibres that provide a key contribution to proprioception and muscle spindle dysfunction is associated with multiple neuromuscular diseases, aging and nerve injuries. To date, there are few publications focussed on de novo generation and characterisation of intrafusal muscle fibres in vitro. To this end, current models of skeletal muscle focus on extrafusal fibres and lack an appreciation for the afferent functions of the muscle spindle. The goal of this study was to produce and define intrafusal bag and chain myotubes from differentiated C2C12 myoblasts, utilising the addition of the developmentally associated protein, Neuregulin 1 (Nrg-1). Intrafusal bag myotubes have a fusiform shape and were assigned using statistical morphological parameters. The model was further validated using immunofluorescent microscopy and western blot analysis, directed against an extensive list of putative intrafusal specific markers, as identified in vivo. The addition of Nrg-1 treatment resulted in a 5-fold increase in intrafusal bag myotubes (as assessed by morphology) and increased protein and gene expression of the intrafusal specific transcription factor, Egr3. Surprisingly, Nrg-1 treated myotubes had significantly reduced gene and protein expression of many intrafusal specific markers and showed no specificity towards intrafusal bag morphology. Another novel finding highlights a proliferative effect for Nrg-1 during the serum starvation-initiated differentiation phase, leading to increased nuclei counts, paired with less myotube area per myonuclei. Therefore, despite no clear collective evidence for specific intrafusal development, Nrg-1 treated myotubes share two inherent characteristics of intrafusal fibres, which contain increased satellite cell numbers and smaller myonuclear domains compared with their extrafusal neighbours. This research represents a minimalistic, monocellular C2C12 model for progression towards de novo intrafusal skeletal muscle generation, with the most extensive characterisation to date. Integration of intrafusal myotubes, characteristic of native, in vivo intrafusal skeletal muscle into future biomimetic tissue engineered models could provide platforms for developmental or disease state studies, pre-clinical screening, or clinical applications.

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