• The Journal of Internal Korean Medicine
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• v.29 no.1
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• pp.243-257
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• 2008

Myostatin, a negative regulator of myogenesis, is shown to function by controlling the proliferation of myoblasts. In this study we show that myostatin is an inhibitor of myoblast differentiation and that this inhibition is mediated through Smad 3. To determine MyoD expression by Dodamtang treatment, we compared the expression pattern of $C_{2}C_{12}$ mouse myoblasts that constitutively express myostatin with control cells. In vitro, increasing concentrations of Dodamtang reversibly prevented the myogenic blockage of myoblasts by myostatin expression. ELISA assay, Western and confocal analysis indicated that treatment of Dodamtang to the low serum culture media increased the levels of MyoD leading to the inhibition of myogenic differentiation by myostatin. The stable transfection of $C_{2}C_{12}$ myoblasts with myostatin expressing constructs did rescue MyoD-induced myogenic differentiation. Consistent with this, the treatment of Dodamtang rescued the expression of a MyoD in $C_{2}C_{12}$ myoblasts treated with myostatin. Taken together, these results suggest that induction of MyoD by Dodamtang inhibits myostatin activity and expression via SMAD3 resulting in the rescue of the myoblasts to differentiate into myotubes. Thus we propose that myostatin action by Dodamtang plays a critical role in myogenic differentiation and that the muscular hyperplasia and hypertrophy seen in animals that blockage of functional myostatin is because of deregulated proliferation and differentiation of myoblasts.

• Journal of Life Science
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• v.17 no.3 s.83
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• pp.420-426
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• 2007

In the present investigation, we studied the modulating effects of (-)-epigallocatechin-3-gallate(EGCG) on the differentiation of mouse C2C12 myoblasts. We found that the strong inhibitory effect of EGCG on DNA methyltransferase-mediated DNA methylation induced transdifferentiation of C2C12 myoblasts into smooth muscle cells demonstrated by both morphological changes and immunofluorescent staining. C2C12 myoblasts treated with EGCG for 4 days expressed smooth muscle ${\alpha}-actin$ protein. Real-time PCR data revealed that smooth muscle ${\alpha}-actin$ mRNA was induced by EGCG treated C2C12 myoblasts in a concentration-dependent manner. Smooth muscle ${\alpha}-actin$ mRNA concentration increased 330% and 490% after 2 and 3 days of 50 ${\mu}M$ of EGCG treatment. The expression of another smooth muscle marker, transgelin, mRNA was also increased up to 9-fold by 4 days of EGCG treatment compared with control in a concentration-dependent manner. These results suggested that C2C12 enables to transdifferentiate into smooth muscle when gene expression patterns are changed by the inhibition of DNA methylation induced by EGCG. In conclusion, transdifferentiation of C2C12 myoblasts into smooth muscle is resulted from the modulating effects of EGCG on DNA methylation which subsequently results in changing the expression pattern of several genes playing a critical role in the differentiation of C2C12 myoblasts.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.7
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• pp.1115-1119
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• 2007

This study was conducted to determine the difference between satellite cells (porcine) and myoblasts (C2C12) in their differentiation under the influence of 2, 4-thiazolidindion. C2C12 myoblast cells and porcine satellite cells (isolated from 10 d old $Landrace{\times}Duroc$ piglets) were grown to absolute confluency. Post confluent cells (day 0) were further exposed to adipogenic induction medium along with 2, 4-thiazolidindion ($8{\mu}M$) for 2 d. Thereafter, cells were exposed to 2, 4-thiazolidindion alone every 2 d till day 10 and analysed. The control was cultured in differentiation medium without any treatment. Increased (p<0.05) expression of transcriptional factors i.e. C/EBP-${\alpha}$ and PPAR-${\gamma}$ and transition of cells to adipocyte morphology was noticed from 2 d and 4 d onwards in satellite cells (Porcine) and myoblasts (C2C12) respectively. Myogenesis was observed to be suppressed completely in case of satellite cells compared to myoblasts in response to 2, 4-thiazolidindion. Pax-7 (transcriptional factor) appeared as a sole entity to satellite cells only, as it was not identified in case of myoblasts. Although both the cells were converting to adipoblasts, the degree of their conversion was different in response to 2, 4-thiazolidindion. Therefore, the hypothesis that satellite cells contribute various domains to the growing myoblasts appeared obscured and found to be dependent on the proliferative energy/or degree of fusion. However, it revealed satellite cells as currency to myoblasts/muscle.

• The Journal of Internal Korean Medicine
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• v.43 no.3
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• pp.344-362
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• 2022

Objective: In this study, the antioxidant activity of Ojayeonjong-hwan extracts was compared, and the following results were obtained. Methods: For hydrothermal and ethanol extracts, DPPH free radical and ABTS cationic radical erasing activity and reducing power using the FRAP method were compared, and the association between the antioxidant power of each extract and total phenol content was investigated. Significant results were obtained through in vitro apoptosis analysis through FFITC staining, mitochondrial membrane potential analysis, and ROS level measurement using C2C12 myoblastoma. Results: 1. In a comparison of DPPH free radical and ABTS cationic radical scavenging activity, water, and 70% ethanol extracts of Ojayeonjong-hwan (WEO and EEO) showed superior radical scavenging ability. 2. In the results of reducing power using the FRAP method, WEO and EEO showed antioxidant activity, which was shown to be dependent on the total phenol content contained in the extracts. 3. In comparison to the protective effect against H₂O₂-induced oxidative stress in C2C12 myoblasts, water extracts had no significant effect, but 70% ethanol extracts inhibited H₂O₂-mediated cytotoxicity in a concentration-dependent manner. 4. The cytotoxic protective effect of EEO against oxidative stress in C2C12 myoblasts was correlated with its inhibitory effects on H₂O₂-induced apoptosis and cell-cycle arrest. 5. In H₂O₂-treated C2C12 myoblasts, the apoptosis inhibitory effects of EEO were associated with the suppression of mitochondrial dysfunction and DNA damage. 6. The protective effects of EEO against H₂O₂-induced oxidative stress in C2C12 myoblasts were directly related to the inhibition of ROS generation. Conclusions: Ojayeonjong-hwan extracts all have protective potential against oxidative stress.

• Animal cells and systems
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• v.12 no.1
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• pp.35-39
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• 2008

Menadione induced cell death in cultured C2 myoblasts. By screening synthetic peptide libraries composed of random sequence of hexapeptides, we identified the hexa-peptides pool of(Ala/Ile)-(Ile/Met)-Val-Ile-Asp-(Met/Ser)-$NH_2$ that protected the myoblasts against menadioneinduced cell death. Pre-incubation with the hexapeptide pool reduced the number of cells detached from culture dish substrate and increased the ratio of relative viability against menadione. In addition, the peptides strongly increased the expression of Bcl-2, an anti-apoptotic protein. These results suggest that the hexapeptides might enhance the resistance to cell death against menadione by increasing the expression of Bcl-2.

• Herbal Formula Science
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• v.29 no.4
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• pp.181-189
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• 2021

Objectives : The calyx of Diospyros kaki Thunb. has usually been used to treat obstinate hiccup. This study investigated the protective effects of Diospyros kaki using C2C12 myoblasts of H₂O₂-induced oxidative stress. Methods : Cell viability and cytotoxicity were determined by MTT assay. The level of reactive oxygen species (ROS), malondialdehyde (MDA), and reduced glutathione (GSH) were measured by using optical properties. Results : The calyx of Diospyros kaki Thunb. extract showed no toxicity to C2C12 myoblasts until 20 ㎍/mL concentration and increased cell viability compared to the H₂O₂ treated group. The calyx of Diospyros kaki Thunb. extract inhibited the production of ROS and MDA at all concentrations. In addition, the calyx of Diospyros kaki Thunb. extract increased the concentration of GSH. Conclusion : This study provides that the calyx of Diospyros kaki Thunb. can be used as a potential material that exhibit antioxidative and protective effects on H₂O₂-induced oxidative stress in C2C12 Myoblasts.

• BMB Reports
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• v.53 no.11
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• pp.605-610
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• 2020

Skeletal myogenesis is a complex process that is finely regulated by myogenic transcription factors. Recent studies have shown that saturated fatty acids (SFA) can suppress the activation of myogenic transcription factors and impair the myogenic differentiation of progenitor cells. Despite the increasing evidence of the roles of miRNAs in myogenesis, the targets and myogenic regulatory mechanisms of miRNAs are largely unknown, particularly when myogenesis is dysregulated by SFA deposition. This study examined the implications of SFA-induced miR-183-5p on the myogenic differentiation in C2C12 myoblasts. Long-chain SFA palmitic acid (PA) drastically reduced myogenic transcription factors, such as myoblast determination protein (MyoD), myogenin (MyoG), and myocyte enhancer factor 2C (MEF2C), and inhibited FHL1 expression and myogenic differentiation of C2C12 myoblasts, accompanied by the induction of miR-183-5p. The knockdown of FHL1 by siRNA inhibited myogenic differentiation of myoblasts. Interestingly, miR-183-5p inversely regulated the expression of FHL1, a crucial regulator of skeletal myogenesis, by targeting the 3'UTR of FHL1 mRNA. Furthermore, the transfection of miR-183-5p mimic suppressed the expression of MyoD, MyoG, MEF2C, and MyHC, and impaired the differentiation and myotube formation of myoblasts. Overall, this study highlights the role of miR-183-5p in myogenic differentiation through FHL1 repression and suggests a novel miRNA-mediated mechanism for myogenesis in a background of obesity.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.6
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• pp.375-379
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• 2003

$Ca^{2+}$ influx appears to be important for triggering myoblast fusion. It remains, however, unclear how $Ca^{2+}$ influx rises prior to myoblast fusion. Recently, several studies suggested that NMDA receptors may be involved in $Ca^{2+}$ mobilization of muscle, and that $Ca^{2+}$ influx is mediated by NMDA receptors in C2C12 myoblasts. Here, we report that other types of ionotropic glutamate receptors, non-NMDA receptors (AMPA and KA receptors), are also involved in $Ca^{2+}$ influx in myoblasts. To explore which subtypes of non-NMDA receptors are expressed in C2C12 myogenic cells, RT-PCR was performed, and the results revealed that KA receptor subunits were expressed in both myoblasts and myotubes. However, AMPA receptor was not detected in myoblasts but expressed in myotubes. Using a $Ca^{2+}$ imaging system, $Ca^{2+}$ influx mediated by these receptors was directly measured in a single myoblast cell. Intracellular $Ca^{2+}$ level was increased by KA, but not by AMPA. These results were consistent with RT-PCR data. In addition, KA-induced intracellular $Ca^{2+}$ increase was completely suppressed by treatment of nifedifine, a L-type $Ca^{2+}$ channel blocker. Furthermore, KA stimulated myoblast fusion in a dose-dependent manner. CNQX inhibited not only KA-induced myoblast fusion but also spontaneous myoblast fusion. Therefore, these results suggest that KA receptors are involved in intracellular $Ca^{2+}$ increase in myoblasts and then may play an important role in myoblast fusion.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.713-717
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• 1998

The synergistic effect of fetal calf serum (FCS) and chicken embryo extract (CEE) on protein synthesis of chicken embryo myoblasts was examined. Myoblasts were derived from chicken embryo cultured for 14 days by trypsin digestion and cultured in 5% $CO^2/95%$ air at $37^{\circ}C$. When myoblasts were cultured at the low level of cell density (20-50% of well), CEE enhanced the ability of FCS to stimulate protein synthesis of myoblasts. However, there was no significant effect of CEE to stimulate protein synthesis of myoblasts cultured at high level of cell density (100% of well).

• BMB Reports
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• v.55 no.2
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• pp.104-109
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• 2022

Skeletal myogenesis is essential to keep muscle mass and integrity, and impaired myogenesis is closely related to the etiology of muscle wasting. Recently, miR-141-3p has been shown to be induced under various conditions associated with muscle wasting, such as aging, oxidative stress, and mitochondrial dysfunction. However, the functional significance and mechanism of miR-141-3p in myogenic differentiation have not been explored to date. In this study, we investigated the roles of miR-141-3p on CFL2 expression, proliferation, and myogenic differentiation in C2C12 myoblasts. MiR-141-3p appeared to target the 3'UTR of CFL2 directly and suppressed the expression of CFL2, an essential factor for actin filament (F-actin) dynamics. Transfection of miR-141-3p mimic in myoblasts increased F-actin formation and augmented nuclear Yes-associated protein (YAP), a key component of mechanotransduction. Furthermore, miR-141-3p mimic increased myoblast proliferation and promoted cell cycle progression throughout the S and G2/M phases. Consequently, miR-141-3p mimic led to significant suppressions of myogenic factors expression, such as MyoD, MyoG, and MyHC, and hindered the myogenic differentiation of myoblasts. Thus, this study reveals the crucial role of miR-141-3p in myogenic differentiation via CFL2-YAP-mediated mechanotransduction and provides implications of miRNA-mediated myogenic regulation in skeletal muscle homeostasis.