• Journal of Ginseng Research
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• v.46 no.3
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• pp.444-453
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• 2022

Background: Compound K (CK) is among the protopanaxadiol (PPD)-type ginsenoside group, which produces multiple pharmacological effects. Herein, we examined the effects of CK on muscle atrophy under hyperlipidemic conditions along with its pro-myogenic effects. Further, the molecular pathways underlying the effects of CK on skeletal muscle have been justified. Methods: C2C12 myotubes were treated with palmitate and CK. C2C12 myoblasts were differentiated using CK for 4-5 days. For the in vivo experiments, CK was administered to mice fed on a high-fat diet for 8 weeks. The protein expression levels were analyzed using western blotting analysis. Target protein suppression was performed using small interfering (si) RNA transfection. Histological examination was performed using Jenner-Giemsa and H&E staining techniques. Results: CK treatment attenuated ER stress markers, such as eIF2a phosphorylation and CHOP expression and impaired myotube formation in palmitate-treated C2C12 myotubes and skeletal muscle of mice fed on HFD. CK treatment augmented AMPK along with autophagy markers in skeletal muscle cells in vitro and in vivo experiments. AMPK siRNA or 3-MA, an autophagy inhibitor, abrogated the impacts of CK in C2C12 myotubes. CK treatment augmented p38 and Akt phosphorylation, leading to an enhancement of C2C12 myogenesis. However, AMPK siRNA abolished the effects of CK in C2C12 myoblasts. Conclusion: These findings denote that CK prevents lipid-induced skeletal muscle apoptosis via AMPK/autophagy-mediated attenuation of ER stress and induction of myoblast differentiation. Therefore, we may suggest the use of CK as a potential therapeutic approach for treating muscle-wasting conditions associated with obesity.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.8
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• pp.1088-1097
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• 2018

Objective: It is commonly accepted that adiponectin binds to its two receptors to regulate fatty acid metabolism in adipocytes. To better understand their functions in the regulation of intramuscular adipogenesis in goats, we cloned the three genes (adiponectin [AdipoQ], adiponectin receptor 1 [AdipoR1], and AdipoR2) encoding these proteins and detected their mRNA distribution in different tissues. We also determined the role of AdipoQ in the adipogenic differentiation of goat skeletal muscle satellite cells (SMSCs). Methods: SMSCs were isolated using 1 mg/mL Pronase E from the longissimus dorsi muscles of 3-day-old female Nanjiang brown goats. Adipogenic differentiation was induced in satellite cells by transferring the cells to Dulbecco's modified Eagle's medium supplemented with an isobutylmethylxanthine, dexamethasone and insulin cocktail. The pEGFP-N1-AD plasmid was transfected into SMSCs using Lipofectamine 2000. Expression of adiponectin in tissues and SMSCs was detected by quantitative polymerase chain reaction and immunocytochemical staining. Results: The three genes were predominantly expressed in adipose and skeletal muscle tissues. According to fluorescence and immunocytochemical analyses, adiponectin protein expression was only observed in the cytoplasm, suggesting that adiponectin is localized to the cytoplasm of goat SMSCs. In SMSCs overexpressing the AdipoQ gene, adiponectin promoted SMSC differentiation into adipocytes and significantly (p<0.05) up-regulated expression of AdipoR2, acetyl-CoA carboxylase, fatty-acid synthase, and sterol regulatory element-binding protein-1, though expression of CCAAT/enhancer-binding $protein-{\alpha}$, peroxisome proliferator-activated receptor ${\gamma}$, and AdipoR1 did not change significantly. Conclusion: Adiponectin induced SMSC differentiation into adipocytes, indicating that adiponectin may promote intramuscular adipogenesis in goat SMSC.

• YAKHAK HOEJI
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• v.33 no.3
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• pp.161-166
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• 1989

Effects of dammarane glycosides of Panax ginseng on primary cultured chicken embryonic skeletal muscle cells were studied by microscopic observation and determination of the activity of acetylcholinesterase. Muscle cells were prepared from the breast of 12-day-old chicken embryo and cultured with either a medium consisted of 87.5% Dulbecco's Modified Eagle Medium (DMEM), 10% horse serum and 2.5% chicken embryonic extract or a medium consisted of 90% DMEM and 10% horse serum. It was observed that dammarane glycosides of Panax ginseng seemed to show the tendency to stimulate the growth and the differentiation of the muscle cells cultured with a medium consisted of 90% DMEM and 10% horse serum under microscopic observation. The activity of acetylcholinesterase in the muscle cells cultured with a medium consisted of 90% DMEM and 10% horse serum was increased by dammarane glycosides of Panax ginseng.

• The Korean Journal of Zoology
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• v.34 no.1
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• pp.31-43
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• 1991

In the present study, the localization of myosin and the pathway of myofibrilogenesis of skeletal muscle cells in culture were investigated by immunocytochemical methods including immunoelectron microscopy and hybridoma formation. There were manly free ribosomes in the cytosol of the myoblast. At 48 hr of the culture, the myofilaments started to form and at 72 hr began to assemble to form myoabrils. At this time the Z band appeared, but the sarcomeres did not link together. Aker 96 hr of culture, adjacent sarcomeres linked together and shotved the typical striation of the skeletal muscle fiber. Myosin was synthesized in free ribosomes at 24 hr of culture and localized at many myofilaments at 48 hr and assembled mvoabrils at 72 hr and at 120 hr of the culture, myosin was localized at thick filaments of the A band.

• Animal Bioscience
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• v.34 no.10
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• pp.1590-1599
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• 2021

Objective: This study investigates the expression patterns of toll-like receptors (TLRs) and intracellular mediators in horse muscle cells after exercise, and the relationship between TLRS expression in stressed horse muscle cells and immune cell migration toward them. Methods: The expression patterns of the TLRs (TLR2, TLR4, and TLR8) and downstream signaling pathway-related genes (myeloid differentiation primary response 88 [MYD88]; activating transcription factor 3 [ATF3]) are examined in horse tissues, and horse peripheral blood mononuclear cells (PBMCs), polymorphonuclear cells (PMNs) and muscles in response to exercise, using the quantitative reverse transcription-polymerase chain reaction (qPCR). Expressions of chemokine receptor genes, i.e., C-X-C motif chemokine receptor 2 (CXCR2) and C-C motif chemokine receptor 5 (CCR5), are studied in PBMCs and PMNs. A horse muscle cell line is developed by transfecting SV-T antigen into fetal muscle cells, followed by examination of muscle-specific genes. Horse muscle cells are treated with stressors, i.e., cortisol, hydrogen peroxide (H₂O₂), and heat, to mimic stress conditions in vitro, and the expression of TLR4 and TLR8 are examined in stressed muscle cells, in addition to migration activity of PBMCs toward stressed muscle cells. Results: The qPCR revealed that TLR4 message was expressed in cerebrum, cerebellum, thymus, lung, liver, kidney, and muscle, whereas TLR8 expressed in thymus, lung, and kidney, while TLR2 expressed in thymus, lung, and kidney. Expressions of TLRs, i.e., TLR4 and TLR8, and mediators, i.e., MYD88 and ATF3, were upregulated in muscle, PBMCs and PMNs in response to exercise. Expressions of CXCR2 and CCR5 were also upregulated in PBMCs and PMNs after exercise. In the muscle cell line, TLR4 and TLR8 expressions were upregulated when cells were treated with stressors such as cortisol, H₂O₂, and heat. Migration of PBMCs toward stressed muscle cells was increased by exercise and oxidative stresses, and combinations of these. Treatment with methylsulfonylmethane (MSM), an antioxidant on stressed muscle cells, reduced migration of PBMCs toward stressed muscle cells. Conclusion: In this study, we have successfully cultured horse skeletal muscle cells, isolated horse PBMCs, and established an in vitro system for studying stress-related gene expressions and function. Expression of TLR4, TLR8, CXCR2, and CCR5 in horse muscle cells was higher in response to stressors such as cortisol, H₂O₂, and heat, or combinations of these. In addition, migration of PBMCs toward muscle cells was increased when muscle cells were under stress, but inhibition of reactive oxygen species by MSM modulated migratory activity of PBMCs to stressed muscle cells. Further study is necessary to investigate the biological function(s) of the TLR gene family in horse muscle cells.

• Journal of Life Science
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• v.22 no.4
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• pp.447-455
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• 2012

Akt plays an important role in a variety of cellular physiologies such as growth, proliferation, and differentiation. In skeletal muscle, Akt has been implicated in regulating regeneration, hypertrophy, and atrophy. In this study, the role of Akt has been examined during skeletal muscle differentiation. Culturing C2C12 myoblasts under low serum (1% horse serum) and high density converted cell morphology from a round shape to an elongated and multi-nucleated shape. Morphological changes were initiated from day 2 of differentiation. In addition, the expression of both myogenin G and myogenin D was elevated from day 2 of differentiation. Skeletal muscle differentiation was abolished by silencing Akt1 or Akt2, but was significantly enhanced by the over-expression of either Akt1 or Akt2. The activation of Akt was observed from day 2 of differentiation and disappeared after day 7. The expression of kruppel-like factor 4 was observed from day 6 of differentiation. Moreover, this expression was blocked in cells silencing either Akt1 or Akt2. In addition, the promoter activity of kruppel-like factor 4 was significantly reduced in cells silencing Akt1 or Akt2. These results suggest that Akt regulates skeletal muscle differentiation through the regulation of kruppel-like factor 4 expression.

• Journal of Animal Science and Technology
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• v.52 no.4
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• pp.329-336
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• 2010

Myogenic satellite cells (MSCs) are mononuclear, multipotent progenitors of adult skeletal muscle possessing a capacity of forming adipocyte-like cells (ALC). To identify the skeletal muscle type-specific myogenic and adipogenic genes during MSCs differentiation, total RNA was extracted from bovine MSCs, myotube-formed cell (MFC), and ALC from each of Beef shank, Longissimus dorsi, Deep pectoral, and Semitendinosus. DNA microarray analysis (24,000 oligo chip) comparing MSCs with MFC and ALC, respectively, revealed 135 differentially expressed genes (> 4 fold) among four cuts. Real-time PCR confirmed expression of 29 genes. Furthermore, the whole tissue sample RNAs analysis showed 6 differentially expressed genes in Beef shank. Among which, 1 gene in MSCs, 4 in MFC, and 1 in ALCs were highly expressed. This study will provide an insight for better understanding the molecular mechanism of differentiation of skeletal muscle type-specific MSCs. The identified genes may be used as marker to distinguish skeletal muscle types.

• YAKHAK HOEJI
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• v.31 no.5
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• pp.296-301
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• 1987

Polyamines of Korean red ginseng were extracted with 5% trichloroacetic acid and purified by ion exchange chromatography using Dowex-50Wx8 resin. Four spots having R$_f$ values of 0.19, 0.28, 0.35, and 0.45 were detected. It was observed under microscopy that those polyamines stimulated the growth and differentiation of chicken embryonic muscle cell. The development of muscle cells from the stage of myoblast to that of myotube was found to be enhanced by those polyamines. It was also observed that those polyamines most likely lengthened, the life-span of the cultured chicken embryonic skeletal muscle cells.

• Parasites, Hosts and Diseases
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• v.36 no.4
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• pp.227-234
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• 1998

Actin and tropomyosin of Cryptosporidium muris were localized by immunogold labeling. Two kinds of antibodies for actin labeling were used. The polyclonal antibody to skeletal muscle (chicken back muscle) actin was labeled on the pellicle and cytoplasmic vacuoles of parasites. The feeder organelle has showed a small amount of polyclonal actin antibody labeling as well. Whereas the monoclonal antibody to smooth muscle (chicken gizzard muscle) actin was chiefly labeled on the filamentous cytoplasm of parasites. The apical portion of host gastric epithelial cell cytoplasm was also labeled by smooth muscle actin together. The polyclonal antibody to tropomyosin was much more labeled at C. muris than host cells, so it could be easily identified even with low magnification (${\times}2,000$). The tropomyosin was observed along the pellicle, cytoplasmic vacuoles, and around the nucleus also. The skeletal muscle type actin seems to play a role in various celluar functions with tropomyosin in C. muris; on the other hand, the smooth muscle type actin was located mainly on the filamentous cytoplasm and supported the parasites firm attachment to host cells. Tropomyosin on the pellicle was thought to be able to stimulate the host as a major antigen through continuous shedding out by the escape of sporozoites or merozoites from their mother cells.

• Molecular & Cellular Toxicology
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• v.4 no.3
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• pp.224-229
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• 2008

Eucommia ulmoides (Duchung) is commonly used for treatment of diabetes in Korean traditional medicine. However, the exact mechanism of its anti-diabetic effect has not yet been fully elucidated. In this study, the effect of E. ulmoides extract on glucose uptake was investigated in L6 rat skeletal muscle cells. E. ulmoides extract stimulated the activity of phosphatidylinositol (PI) 3-kinase that is a major regulatory molecule in glucose uptake pathway. Protein kinase B (PKB) and protein kinase C-${\xi}$ (PKC-${\xi}$), downstream mediators of PI 3-kinase, were also activated by E. ulmoides extract. We assessed the activity of AMP-activated protein kinase (AMPK), another regulatory molecule in glucose uptake pathway. Phosphorylation level of AMPK did not change with treatment of E. ulmoides extract. Phosphorylations of p38 mitogen activated protein kinase (p38 MAPK) and acetyl-CoA carboxylase (ACC), downstream mediators of AMPK, were not significantly different. Taken together, our results suggest that E. ulmoides may stimulate glucose uptake through PI 3-kinase but not AMPK in L6 skeletal muscle cells.