• Journal of Life Science
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• v.30 no.9
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• pp.772-782
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• 2020

Skeletal muscle differentiation or myogenesis is important to maintain muscle mass and metabolic homeostasis. Muscle-specific microRNAs (miRNAs) are known to play a critical role in skeletal myogenic differentiation. In this study, we examined the expression profiling of miRNAs during myogenic differentiation in rat L6 myoblasts using rat miRNA microarrays. We identified the upregulated expression of miR-128 as well as several well-known myogenic miRNAs, including miR-1, miR-133b, and miR-206. We additionally confirmed the increased expression of miR-128 observed on microarray through quantitative real-time PCR (qRT-PCR), which showed similarly upregulated expression of both primary miR-128 and mature miR-128, consistent with the microarray findings. Furthermore, transfection of miR-128 into rat L6 myoblasts induced gene expression of myogenic markers such as muscle creatine kinase (MCK), myogenin, and myosin heavy chain (MHC). Protein expression of MHC was increased as well. Inhibition of miR-128 by inhibitory peptide nucleic acids (PNAs) blocked the expression of those myogenic markers. In addition, the transfection of miR-128 into rat L6 myoblasts enhanced the phosphorylation of Erk and Akt proteins stimulated by insulin, while simultaneously reversing the inhibited phosphorylation of Erk and Akt due to insulin resistance. These findings suggest that miR-128 may play important roles in myogenic differentiation and insulin signaling.

• Journal of Ginseng Research
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• v.44 no.3
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• pp.435-441
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• 2020

Background: As a process of aging, skeletal muscle mass and function gradually decrease. It is reported that ginsenoside Rb1 and Rb2 play a role as AMP-activated protein kinase activator, resulting in regulating glucose homeostasis, and Rb1 reduces oxidative stress in aged skeletal muscles through activating the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. We examined the effects of Rb1 and Rb2 on differentiation of the muscle stem cells and myotube formation. Methods: C2C12 myoblasts treated with Rb1 and/or Rb2 were differentiated and induced to myotube formation, followed by immunoblotting for myogenic marker proteins, such as myosin heavy chain, MyoD, and myogenin, or immunostaining for myosin heavy chain or immunoprecipitation analysis for heterodimerization of MyoD/E-proteins. Results: Rb1 and Rb2 enhanced myoblast differentiation through accelerating MyoD/E-protein heterodimerization and increased myotube hypertrophy, accompanied by activation of Akt/mammalian target of rapamycin signaling. In addition, Rb1 and Rb2 induced the MyoD-mediated transdifferentiation of the rhabdomyosarcoma cells into myoblasts. Furthermore, co-treatment with Rb1 and Rb2 had synergistically enhanced myoblast differentiation through Akt activation. Conclusion: Rb1 and Rb2 upregulate myotube growth and myogenic differentiation through activating Akt/mammalian target of rapamycin signaling and inducing myogenic conversion of fibroblasts. Thus, our first finding indicates that Rb1 and Rb2 have strong potential as a helpful remedy to prevent and treat muscle atrophy, such as age-related muscular dystrophy.

• Korean journal of food and cookery science
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• v.26 no.3
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• pp.323-329
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• 2010

Studies on the tenderizing effect of fruits has been limited even though fig, kiwifruit, pear, and pineapple cultivated in Korea are utilized commonly during cooking for their proteolytic properties. Therefore, the characteristics of these fruits were investigated by treating beef with their crude protease extracts. The protease effects of crude protease extract from the fruits on casein and myofibrilar protein were in the following order : pineapple > kiwifruit > fig > pear. Electrophoretic analysis results found that pineapple, kiwifruit, and fig cleaved myosin heavy chain into smaller fragments. The myofibrilar fragmentation ratio of crude protease extracts was the highest for pineapple whileas the lowest for pear. Ground fruits (5% and 10%) increased amounts of soluble nitrogen and decreased shear force of beef. Pineapple was the most effective while pear was the least effective. Decrease in springiness and gumminess was observed by texture profile analysis of beef treated with fruits, especially pineapple and kiwifruit. Among the 5% treatments, pineapple and kiwifruit produced the highest tenderness. Additionally, 10% treatment was less preferable than the 5% treatment.

• Food Science of Animal Resources
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• v.27 no.4
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• pp.457-462
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• 2007

Effects of sonication on water-solubilization of myofibril from breast muscle of spent hen effects investigated in this study. To evaluate effect of salt concentration and pH, salt concentration was varied with range from 0.1 to 0.8 M, and pH was varied with range from 6.0 to 8.0. Solubility, SDS-PAGE, viscosity and ATPase activity of sonicated myofibril were measured. Solubility of myofibrillar protein containing 0.1 M NaCl at pH 8.0 after sonication was above 90%. Main components of soluble protein by SDS-PAGE were myosin heavy chain and actin. That is, it indicated breaking of myofibril structure by sonication. Also, viscosity of soluble protein increased, but Ca- and Mg-ATPase activities decreased by increasing sonication time. From these results, we concluded that most of myofibrillar proteins were denatured by sonication.

• Animal Bioscience
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• v.34 no.9
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• pp.1514-1524
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• 2021

Objective: This study investigated the meat quality characteristics, endogenous proteolytic enzymes, collagen content, and myosin heavy chain (MyHC) isoforms of different muscles of Thai native cattle (TNC). Methods: Infraspinatus (IF), Longissimus thoracis (LT), and Supraspinatus (SS) muscles were obtained from two TNC breeds, Kho-Lan (KL, n = 7) and Kho-Isaan (KI, n = 7). The muscle and meat characteristics of TNC breeds and their relationship with MyHC expression were examined. Results: Three MyHC isoforms namely MyHC I, MyHC IIa, and MyHC IIx were detected in the muscles. The KL had higher (p<0.05) MyHC IIx than the KI. The IF muscle had higher (p<0.05) MyHC I compared to other muscles. The LT muscle had the least MyHC I. The LT had higher (p<0.05) MyHC IIx than the IF and SS muscles. The IF presented the least MyHC IIx. The KL had higher (p<0.05) lightness and moisture content and lower crude protein, redness, cooking loss, shear force, and calpastatin than the KI. The glycogen, total collagen, soluble collagen, crude protein, ash contents, and troponin T degradation product of IF and SS were lower (p<0.05) than that of LT. Ether extract in LT was lower (p<0.05) than that of IF and SS. The percentage of MyHC I, MyHC IIa, and MyHC IIx were significantly correlated with muscle and meat characteristics of TNC. Conclusion: These results suggest that the differences in the MyHC isoforms may partly account for the variation in meat quality between breeds and among muscles of TNC.

• Journal of Korean Medicine for Obesity Research
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• v.23 no.2
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• pp.60-68
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• 2023

Objectives: This study was conducted to compare the effects of Hominis placenta (Jahage, J) and wild ginseng (SanSam, S) pharmacopuncture drugs on muscle differentiation and energy metabolism regulation in C2C12 myotubes. Methods: The C2C12 myoblasts were differentiated into myotubes for 5 days by replacing in medium containing 2% horse serum and then treated with J and S pharmacopuncture extract at different concentrations for 24 hr. The expression of myosin heavy chain and energy metabolism-regulating factors, myosin heavy chain (MHC), nuclear respiratory factor-1 (NRF-1), and proliferator-activated receptor γ coactivator-1 alpha (PGC-1α) were determined in C2C12 myotubes by western blot. Additionally, the phosphorylation of AMPK and the expression of mitochondrial biogenesis, including sirtuin 1 (SIRT1) were determined in the myotubes. Results: As a result, treatment with J and S pharmacopuncture extract at 0.1 and 1 mg/mL increased the MHC expression in C2C12 myotubes compared with non-treated cells, but only S pharmacopuncture was shown a significant and distinct increase in the expression. Expression of TFAM and NRF-1 was also shown significant increases in S and J pharmacopuncture in C2C12 myotubes compared to non-treated cells. The phosphorylation of AMPK and the expression of PGC-1α and SIRT1 showed increased expression in S and J pharmacopuncture compared to non-treated cells. The effect of low-dose of J pharmacopuncture on the phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and PGC-1α expression was greater than that of S pharmacopuncture. Conclusions: In conclusion, both J and S pharmacopuncture promote muscle differentiation in C2C12 myoblasts into myotubes and energy metabolism through the AMPK/SIRT1 signaling pathway. This indicates that the pharmacopuncture with tonic herbal medicines can help to improve skeletal muscle function.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.385-391
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• 2010

This study was conducted to compare proteins expressed in M. longissimus from Hanwoo and Holstein steers immediately after slaughter. Two-dimensional electrophoresis (2DE)/LC-MS/MS analysis revealed that the total number of detectable protein spots from longissimus muscle tissues was slightly higher in Hanwoo ($575{\pm}65$) than Holstein ($534{\pm}13$) steers, but that these numbers were not statistically significant due to large variation between replicates. A total of twelve protein spots did not match between sample groups, eight of which were expressed in the Hanwoo sample and four that were expressed in the Holstein sample. The protein spots detected in the Hanwoo sample included smooth muscle and non-muscle myosin alkali light chain 6B isomers, ${\alpha}B$ crystallin isomers, hemoglobin ${\beta}$-A chains, slow myosin heavy chains, and slow skeletal muscle troponin T chains. Collectively, these proteins are a class of slow-twitch muscle fiber and mirror that Hanwoo muscle tissue sampled for the current study contained more slow-twitch muscle fibers than Holstein one. Conversely, proteins detected from the Holstein sample included ankyrin repeat domain 2 and creatin kinase isomers. Given that creatin kinase isomers are related to the fast-twitch muscle, these results likely indicate that Holstein muscle tissue sampled for the current study contained more fast-twitch muscle fibers than Hanwoo beef.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.11
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• pp.1620-1632
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• 2017

Objective: This study evaluated the effects of a traditional Chinese medicine formula (TCMF) on muscle fiber characteristics in finishing pigs and the effects of the formula's extract (distilled water, ethyl acetate and petroleum ether extraction) on porcine cell proliferation and isoforms of myosin heavy chain (MyHC) gene expression in myocytes. Methods: In a completely randomized design, ninety pigs were assigned to three diets with five replications per treatment and six pigs per pen. The diets included the basal diet (control group), TCMF1 (basal diet+2.5 g/kg TCMF) and TCMF2 (basal diet+5 g/kg TCMF). The psoas major muscle was obtained from pigs at the end of the experiment. Muscle fiber characteristics in the psoas major muscle were analyzed using myosin ATPase staining. Cell proliferation was measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye and cytometry. Isoforms of MyHC gene expression were detected by real-time quantitative polymerase chain reaction. Results: The final body weight and carcass weight of finishing pigs were increased by TCMF1 (p<0.05), while the psoas major muscle cross-sectional area was increased by TCMF (p<0.05). The cross-sectional area and diameter of psoas major muscle fiber Ι, IIA, and IIB were increased by TCMF2 (p<0.05). The cross-sectional area and fiber diameter of psoas major muscle fiber IIA and IIB were increased by diet supplementation with TCMF1 (p<0.05). Psoas major muscle fiber IIA and IIB fiber density from the pigs fed the TCMF1 diet and the type IIB fiber density from the pigs fed the TCMF2 diet were lower compared to pigs fed the control diet (p<0.05). Pigs fed TCMF2 had a higher composition of type Ι fiber and a lower percentage of type IIB fiber in the psoas major muscle (p<0.05). The expression levels of MyHC Ι, MyHC IIa, and MyHC IIx mRNA increased and the amount of MyHC IIb mRNA decreased in the psoas major muscle from TCMF2, whereas MyHC Ι and MyHC IIx mRNA increased in the psoas major muscle from TCMF1 (p<0.05). Peroxisome proliferator-activated receptor ${\gamma}$ $coactivator-1{\alpha}$ and CaN mRNA expression in the psoas major muscle were up-regulated by TCMF (p<0.05). Porcine skeletal muscle satellite cell proliferation was promoted by $4{\mu}g/mL$ and $20{\mu}g/mL$ TCMF water extraction (p<0.05). Both $1{\mu}g/mL$ and $5{\mu}g/mL$ of TCMF water extraction increased MyHC IIa, MyHC IIb, and MyHC IIx mRNA expression in porcine myocytes (p<0.05), while MyHC Ι mRNA expression in porcine myocytes was decreased by $5{\mu}g/mL$ TCMF water extraction (p<0.05). Porcine myocyte MyHC Ι and MyHC IIx mRNA expression were increased, and MyHC IIa and MyHC IIb mRNA expression were down-regulated by $5{\mu}g/mL$ TCMF ethyl acetate extraction (p<0.05). MyHC Ι and MyHC IIa mRNA expression in porcine myocytes were increased, and the MyHC IIb mRNA expression was decreased by $1{\mu}g/mL$ TCMF ethyl acetate extraction (p<0.05). Four isoforms of MyHC mRNA expression in porcine myocytes were reduced by $5{\mu}g/mL$ TCMF petroleum ether extraction (p<0.05). MyHC IIa mRNA expression in porcine myocytes increased and MyHC IIb mRNA expression decreased by $1{\mu}g/mL$ in a TCMF petroleum ether extraction (p<0.05). Conclusion: These results indicated that TCMF amplified the psoas major muscle cross-sectional area through changing muscle fiber characteristics in finishing pigs. This effect was confirmed as TCMF extraction promoted porcine cell proliferation and affected isoforms of MyHC gene expression in myocytes.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.5
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• pp.757-766
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• 2014

Postnatal muscle hypertrophy of beef cattle is the result of enhanced myofibrillar protein synthesis and reduced protein turnover. Skeletal muscle hypertrophy has been studied in cattle fed ${\beta}$-adrenergic agonists (${\beta}$-AA), which are receptor-mediated enhancers of protein synthesis and inhibitors of protein degradation. Feeding ${\beta}$-AA to beef cattle increases longissimus muscle cross-sectional area 6% to 40% compared to non-treated cattle. The ${\beta}$-AA have been reported to improve live animal performance, including average daily gain, feed efficiency, hot carcass weight, and dressing percentage. Treatment with ${\beta}$-AA increased mRNA concentration of the ${\beta}_2$ or ${\beta}_1$-adrenergic receptor and myosin heavy chain IIX in bovine skeletal muscle tissue. This review will examine the effects of skeletal muscle and adipose development with ${\beta}$-AA, and will interpret how the use of ${\beta}$-AA affects performance, body composition, and growth in beef cattle.

• Food Science of Animal Resources
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• v.35 no.4
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• pp.533-540
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• 2015

The aim of this study was to investigate the effects of aqueous extract from Sarcodon aspratus on tenderization of the bovine longissimus dorsi muscles in comparison with commercial proteolytic enzymes. Furthermore, meat quality and muscle protein degradation were examined. We marinated meat with 2% Sarcodon aspratus extract, 2% kiwi extract, and 0.2% papain. Beef chunks (3×3×3 cm³) were marinated with distilled water (control), Sarcodon aspratus extract (T1), kiwi extract (T2) or papain (T3) for 48 h at 4℃. There were no significant differences in muscle pH and lightness between control and treated samples. T1 had the lowest redness (p<0.01), and higher cooking loss and water holding capacity than control and T2 (p<0.05). T1 and T3 exhibited lower shear force values than control (p<0.05). Total protein solubility did not differ significantly between T1 and control, but T1 had less myofibrillar protein solubility than control and T2 (p<0.001). The degradation of myosin heavy chain in T1 and T3 was observed. This degradation of myofibrillar protein suggests that Sarcodon aspratus extract could influence tenderization. These results show that aqueous extract of Sarcodon aspratus extract actively affect the tenderness of the bovine longissimus dorsi muscle.