• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.19-24
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• 2016

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality worldwide. The exploration of new biomarkers with high sensitivity and specificity for early diagnosis of AMI therefore becomes one of the primary task. In the current study, we aim to detect whether there is any heart specific long noncoding RNA (lncRNA) releasing into the circulation during AMI, and explore its function in the neonatal rat cardiac myocytes injury induced by $H_2O_2$. Our results revealed that the cardiac-specific lncRNA MHRT (Myosin Heavy Chain Associated RNA Transcripts) was significantly elevated in the blood from AMI patients compared with the healthy control ($^*p<0.05$). Using an in vitro neonatal rat cardiac myocytes injury model, we demonstrated that lncRNA MHRT was upregulated in the cardiac myocytes after treatment with hydrogen peroxide ($H_2O_2$) via real-time RT-PCR (qRT-PCR). Furthermore, we knockdowned the MHRT gene by siRNA to confirm its roles in the $H_2O_2$-induced cardiac cell apoptosis, and found that knockdown of MHRT led to significant more apoptotic cells than the non-target control ($^{**}p<0.01$), indicating that the lncRNA MHRT is a protective factor for cardiomyocyte and the plasma concentration of MHRT may serve as a biomarker for myocardial infarction diagnosis in humans AMI.

• Animal cells and systems
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• v.1 no.4
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• pp.641-646
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• 1997

Lysophosphatidic acid (LPA; 1-acyl-glycerol-3-phosphate) has been known as an intercellular phospholipid messenger with a wide range of biological activities. In this study, the effect of LPA on both the proliferation and differentiation of rat E63 myoblasts has been investigated. In the serum-free Insulin-Transferrin-Selenium (ITS) media, the proliferation of E63 cells was largely restricted. Addition of LPA into the ITS media strongly promoted the cell proliferation and resulted in two to four fold increase of cell number. Furthermore, it appeared to increase the percent fusion in a dose-dependent manner up to 15 ug/ml. The synthesis of myosin heavy chain (MHC) was increased by LPA as well. These results indicate that LPA is able to promote both cell proliferation and differentiation in rat E63 myoblasts. Suramin, known to have uncoupling activity on growth factor-receptor interaction, was tested for antagonistic activity in myoblast proliferation and differentiation. Myoblasts grown in the ITS medium containing LPA were able to proliferate well even in the presence high concentration of suramin whereas myoblast differentiation was completely blocked by 30 ug/ml of suramin. The inhibitory effect of suramin on the myoblast differentiation was completely reversible by removing the suramin. This result indicates that the intracellular signaling pathway of LPA leading to cell proliferation might be distinct from that leading to cell differentiation on E63 myoblasts. Also, the antagonistic effect of suramin suggests that the differentiation activity elicited by LPA might be mediated by a specific G protein-coupled receptor.

• Molecules and Cells
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• v.26 no.1
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• pp.81-86
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• 2008

RNA interference (RNAi) was performed on several essential genes in the pinewood nematode Bursaphelenchus xylophilus, which causes pine wilt disease. Double-stranded RNA (dsRNA) was delivered to larvae or adult worms by soaking, electroporation, or microinjection. Soaking and electroporation of L2-L3 stage worms in solutions containing dsRNA for essential genes induced over 25% lethality after 5 days, and gene-specific phenotypes were observed. This lethality agreed with significant reductions of the targeted transcripts, as assayed by reverse-transcription coupled with real time PCR. Microinjection was the most efficient route as measured by the hatching rate of F1 embryos, which was reduced by 46%. When adult worms were soaked in dsRNA, lethality was induced in the F1 larvae, revealing the persistence of knockdown phenotypes. The penetrance of the RNAi phenotypes for essential genes was relatively low but consistent, indicating that RNAi should be useful for studying the in vivo functions of B. xylophilus gene products.

• Food Science of Animal Resources
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• v.39 no.6
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• pp.888-902
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• 2019

Our aim was to investigate the effects of bromelain embedded in double emulsion (DE) on physicochemical properties of pork loin. We evaluated DE characteristics such as size, zeta potential, and microscopy after fabrication. We marinated meat with distilled water (DW), 1% (w/v) bromelain solution, blank DE, and 1% (w/v) bromelain loaded in double emulsion (DE E) for 0, 24, 48, and 72 h at 4℃, and prepared raw meat for control. The marinated samples were assessed for color, water holding capacity, cooking loss, moisture content, pH, protein solubility, Warner-Bratzler shear force (WBSF) and gel electrophoresis. The droplet size of 1% (w/v) bromelain embedded in DE was increased compared with blank DE (p<0.05) and values of zeta potential decreased. The increase in lightness and color difference range of the DE-treated group was lower than that of the DW-treated group (p<0.05). Moreover, treatment by immersion in 1% (w/v) DE E resulted in the highest water holding capacity values (p<0.05) and lower cooking loss values than water base treatment (p<0.05). Results for myofibrillar protein solubility and WBSF showed a similar trend. 1% (w/v) DE E showed degradation of myosin heavy chain after 48 h in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Thus, bromelain-loaded DE is useful for controlling and handling enzyme activity in food industry.

• Korean Journal of Food Science and Technology
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• v.22 no.5
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• pp.569-574
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• 1990

The influence of NaCl and pH on degradation of chicken breast muscle myofibrillar proteins by porcine leukocyte lysosomal proteinases was investigated. The degradation reactions were carried out at $38^{\circ}C$ for 24hours under different conditions. The degradation of myofibrillar proteins by leukocyte lysosomal enzymes at various pH values was limited to partial hydrolysis. Reactions at higher pH values resulted in lower molecular weight degradation products while reactions at lower pH resulted in higher molecular weight degradation products. When NaCl was added into the reaction mixture, enzyme activities of degradation were increased at all pH values studied, as evidenced by NPN-analysis and SDS-PAGE. More severe degradation was observed with higher salt concentration. The concentration of 0.5M NaCl in the reaction mixture gave more degradation of myosin heavy chain by enzyme than that of 0.1M NaCl.

• Food Science of Animal Resources
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• v.29 no.3
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• pp.317-324
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• 2009

In order to reduce the increased hardness of beef bulgogi due to hydrostatic pressure (HP), kiwifruit (Actinidia chinensis) was applied. To understand the changes of shear force in beef bulgogi with kiwifruit induced by HP, changes in chemical properties of myofibril (Mf) with 10% kiwifruit induced by HP were investigated. From the SDS-PAGE patterns of Mf with 10% kiwifruit, there was an observed increase in the degradation of myosin heavy chain (MHC) by HP (300-500 MPa) to that by 0.1 MPa. This result indicates that HP may enhance enzyme action from a kiwifruit for the degradation of MHC, and the similar phenomenon occurred in the beef bulgogi with kiwifruit induced by HP. The shear force of beef bulgogi without a kiwifruit induced by 400 and 500 MPa significantly increased compared to that by 0.1 MPa (p<0.05). However, in the beef bulgogi with 10% or 20% kiwifruit, the shear force induced by 400 or 500 MPa was similar or slightly lower than that by 0.1 MPa. Consequently, adding kiwifruit to bulgogi could reduce the hardness of HP-induced beef bulgogi due to the enzyme action in the kiwifruit accelerated by HP.

• Animal Bioscience
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• v.36 no.2
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• pp.295-306
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• 2023

Objective: Inhibiting the p38 mitogen-activated protein kinase (MAPK) signaling pathway delays differentiation and increases proliferation of muscle stem cells in most species. Here, we aimed to investigate the effect of p38 inhibitor (p38i) treatment on the proliferation and differentiation of chicken muscle stem cells. Methods: Chicken muscle stem cells were collected from the muscle tissues of Hy-line Brown chicken embryos at embryonic day 18, then isolated by the preplating method. Cells were cultured for 4 days in growth medium supplemented with dimethyl sulfoxide or 1, 10, 20 μM of p38i, then subcultured for up to 4 passages. Differentiation was induced for 3 days with differentiation medium. Each treatment was replicated 3 times. Results: The proliferation and mRNA expression of paired box 7 gene and myogenic factor 5 gene, as well as the mRNA expression of myogenic differentiation marker gene myogenin were significantly higher in p38i-treated cultures than in control (p<0.05), but immunofluorescence staining and mRNA expression of myosin heavy chain (MHC) were not significantly different between the two groups. Oil red O staining of accumulated lipid droplets in differentiated cell cultures revealed a higher lipid density in p38i-treated cultures than in control; however, the expression of the adipogenic marker gene peroxisome proliferator activated receptor gamma was not significantly different between the two groups. Conclusion: p38 inhibition in chicken muscle stem cells improves cell proliferation, but the effects on myogenic differentiation and lipid accumulation require additional analysis. Further studies are needed on the chicken p38-MAPK pathway to understand the muscle and fat development mechanism.

• The Korea Journal of Herbology
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• v.35 no.3
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• pp.9-16
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• 2020

Objectives : Sarcopenia is a disease that leads to a decrease in skeletal muscle, and the importance of prevention and treatment thereof is increasing in an aging society. However, there is a definite limitation of exercise therapy for sarcopenia, and thus, there is an urgent need for a pharmacologic research to the treatment of sarcopenia. Methods : 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay was performed to confirm the antioxidant efficacy of water extract of Lacca Sinica Exsiccata (WELSE). To determine the effect of WELSE on myoblast activity, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay was performed. To confirm the effect of WELSE on the differentiation of myoblast into myotubes, protein expression levels of myosin heavy chain 3 (Myh3) and paired box 3/7 (pax3/7) were confirmed by immunoblot analysis. In addition, immunofluorescence microscopy was performed to confirm the effect on myotube formation of WELSE. Results : It was confirmed that WELSE had high antioxidant activity and showed no cytotoxicity to myoblast up to 200 ㎍/㎖ concentration. Myoblast was treated with WELSE at a concentration of 100 ㎍/㎖ and differentiated for 5 days. The expression of Myh3, which forms myotubes, was promoted and the morphology of myotubes was changed and Increasing the thickness. Conclusions : In this paper, we confirmed the excellent antioxidant efficacy of WELSE and positive effects on muscle differentiation and myotube formation. These results suggest valuable as a material for pharmaceutical research on the prevention and treatment of sarcopenia.

• The Korea Journal of Herbology
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• v.35 no.3
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• pp.25-32
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• 2020

Objectives : At present, aging-related degenerative muscle diseases are considered a serious problem. However, the effects on muscles regarding the efficacy of blueberry have not been studied. In this study, we tried to find out the correlation between blueberry and muscle. Methods : 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay was performed to confirm the antioxidant efficacy of blueberry hydrothermal extract. To determine the effect of blueberry hydrothermal extracts (BHE) on myoblast activity, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay was performed. To confirm the effect of blueberry hydrothermal extracts on the differentiation of myoblast into myotubes, protein expression levels of myosin heavy chain 3 (Myh3) and paired box 3/7 (pax3/7) were confirmed by immunoblot analysis. In addition, immunofluorescence microscopy was performed to confirm the effect on myotube formation of blueberry hydrothermal extracts. Results : Antioxidative efficacy and low toxicity were confirmed through ABTS assay and MTS assay of blueberry extract for myoblasts. As a result of immunoblot analysis and immunofluorescence analysis, the decrease in myogenic marker Pax3/7 was not confirmed, but myotubes The specific expression inhibitory activity of the forming protein Myh3 was confirmed. Through this, it was confirmed that the blueberry extract has a negative activity against myoblast differentiation. Conclusion : This experiment confirmed that blueberry hydrothermal extract has excellent antioxidant efficacy and negative results in inhibiting the differentiation and proliferation of myoblast. This requires deep study of certain ingredients and requires reassessment of the dietary intake of blueberries.

• Korean Journal of Exercise Nutrition
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• v.24 no.2
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• pp.11-21
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• 2020

[Purpose] Doxorubicin (DOX) is a potent anti-cancer drug that appears to have severe myotoxicity due to accumulation. The skeletal muscle has a regeneration capacity through satellite cell activation when exposed to extracellular stimulus or damage. Endurance exercise (EXE) is a therapeutic strategy that improves pathological features and contributes to muscle homeostasis. Thus, this study investigated the effect of EXE training in mitigating chronic DOX-induced myotoxicity. [Methods] Male C57BL/6J mice were housed and allowed to acclimatize with free access to food and water. All the mice were randomly divided into four groups: sedentary control (CON, n=9), exercise training (EXE, n=9), doxorubicin treatment (DOX, n=9), doxorubicin treatment and exercise training (DOX+EXE, n=9) groups. The animals were intraperitoneally injected with 5 mg/kg/week of DOX treatment for 4 weeks, and EXE training was initiated for treadmill adaptation for 1 week and then performed for 4 weeks. Both sides of the soleus (SOL) muscle tissues were dissected and weighed after 24 hours of the last training sessions. [Results] DOX chemotherapy induced an abnormal myofiber's phenotype and transition of myosin heavy chain (MHC) isoforms. The paired box 7 (PAX7) and myoblast determination protein 1 (MYOD) protein levels were triggered by DOX, while no alterations were shown for the myogenin (MYOG). DOX remarkably impaired the a-actinin (ACTN) protein, but the EXE training seems to repair it. DOX-induced myotoxicity stimulated the expression of the forkhead box O3 (FOXO3a) protein, which was accurately controlled and adjusted by the EXE training. However, the FOXO3a-mediated downstream markers were not associated with DOX and EXE. [Conclusion] EXE postconditioning provides protective effects against chronic DOX-induced myotoxicity, and should be recommended to alleviate cancer chemotherapy-induced late-onset myotoxicity.