• 대한본초학회지
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• 제35권3호
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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.

• 대한의생명과학회지
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• 제12권3호
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• pp.201-208
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• 2006

PI3-kinase activity through p85, the regulatory subunit of class IA PI3-kinase, is indispensable for the growth, differentiation, and survival of skeletal muscle cells, but little is known about the function of other regulatory subunits such as p55 and p50. We examined the subcellular localization and the expression of the regulatory subunits of class IA PI3-kinase in L6 myoblasts. Both p55 and p50 as well as p85 were expressed in L6 myoblasts. Whereas p85 was localized at both cytosolic and nuclear tractions, p55 and p50 were localized at only the nuclear traction. During the differentiation of L6 myoblasts, the protein concentrations of both p55 and p50 were decreased but that of p85 was not significantly changed. Menadione-induced oxidative stress induced the translocation of p85 from cytosol to nucleus and the increase of p55 expression. These results suggest that the regulatory subunits of class IA PI3-kinase play an important role in L6 myoblasts.

• BMB Reports
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• 제49권6호
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• pp.303-304
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• 2016

Myoblast fusion is important for skeletal muscle formation. Even though the knowledge of myoblast fusion mechanism has accumulated over the years, the initial signal of fusion is yet to be elucidated. Our study reveals the novel function of a phosphatidylserine (PS) receptor, stabilin-2 (Stab2), in the modulation of myoblast fusion, through the recognition of PS exposed on myoblasts. During differentiation of myoblasts, Stab2 expression is higher than other PS receptors and is controlled by calcineurin/NFAT signaling on myoblasts. The forced expression of Stab2 results in an increase in myoblast fusion; genetic ablation of Stab2 in mice causes a reduction in muscle size, as a result of impaired myoblast fusion. After muscle injury, muscle regeneration is impaired in Stab2-deficient mice, resulting in small myofibers with fewer nuclei, which is due to reduction of fusion rather than defection of myoblast differentiation. The fusion-promoting role of Stab2 is dependent on its PS-binding motif, and the blocking of PS-Stab2 binding impairs cell-cell fusion on myoblasts. Given our previous finding that Stab2 recognizes PS exposed on apoptotic cells for sensing as an "eat-me" signal, we propose that PS-Stab2 binding is required for sensing of a "fuse-me" signal as the initial signal of myoblast fusion.

• BMB Reports
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• 제53권5호
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• pp.278-283
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• 2020

Muscle fibers are generally formed as multinucleated fibers that are differentiated from myoblasts. Several reports have identified transcription factors and proteins involved in the process of muscle differentiation, but the roles of microRNAs (miRNAs) in myogenesis remain unclear. Here, comparative analysis of the miRNA expression profiles in mouse myoblasts and gastrocnemius (GA) muscle uncovered miR-3074-3p as a novel miRNA showing markedly reduced expression in fully differentiated adult skeletal muscle. Interestingly, elevating miR-3074-3p promoted myogenesis in C2C12 cells, primary myoblasts, and HSMMs, resulting in increased mRNA expression of myogenic makers such as Myog and MyHC. Using a target prediction program, we identified Caveolin-1 (Cav1) as a target mRNA of miR-3074-3p and verified that miR-3074-3p directly interacts with the 3' untranslated region (UTR) of Cav1 mRNA. Consistent with the findings in miR-3074-3p-overexpressing myoblasts, knockdown of Cav1 promoted myogenesis in C2C12 cells and HSMMs. Taken together, our results suggest that miR-3074-3p acts a positive regulator of myogenic differentiation by targeting Cav1.

• Asian-Australasian Journal of Animal Sciences
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• 제20권4호
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• pp.501-510
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• 2007

The present study was conducted to establish primary bovine muscle satellite cell (MSC) culture conditions and to investigate the effects of various steroid hormones on transcription of the genes involved in muscle cell proliferation and differentiation. Of three different types of proteases (type II collagenase, pronase and trypsin-EDTA) used to hydrolyze the myogenic satellite cells from muscle tissues, trypsin-EDTA treatment yielded the highest number of cells. The cells separated by hydrolysis with type II collagenase and incubated on gelatin-coated plates showed an enhanced cell attachment onto the culture plate and cell proliferation at an initial stage of cell growth. In this study, the bovine MSCs were maintained in vitro up to passage 16 without revealing any significant morphological change, and even to when the cells died at passage 21 with decreased or almost no cell growth or deformities. When the cells were incubated in a steroid-depleted environment (DMEM(-)/10% CDFBS (charcoal-dextran stripped FBS)), they grew slowly initially, and were widened and deformed. In addition, when the cells were transferred to an incubation medium containing steroid (DMEM(+)/10% FBS), the deformed cells resumed their growth and returned to a normal morphology, suggesting that steroid hormones are crucial in maintaining normal MSC morphology and growth. The results demonstrated that treatments with 19-nortestosterone and testosterone significantly increased AR gene expression (p<0.05), implying that both testosterone and 19-nortestosterone bind with AR and that the hormone bound-AR complex up-regulates the genes of its own receptor (AR) plus other genes involved in satellite cell growth and differentiation in bovine muscle.

• 생명과학회지
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• 제23권1호
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• pp.137-142
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• 2013

인체 중간엽 줄기세포는 지방세포, 골세포, 연골세포, 근육세포 등 여러 형태의 세포로의 분화되는 것이 특징이다. 특히, 최근 연구 결과를 살펴 보면, 중간엽 줄기세포는 생체 내에서 조직 특이적인 세포 형태로 분화 된다. 본 연구에서는 염증 상태에 존재하는 중간엽 줄기 세포가 혈관 형성에 관여하는지 알아보고, 염증 상태에 존재하는 줄기세포의 역할을 규명하고자 본 연구를 진행하였다. 생체 내 염증 상태와 유사한 환경을 만들고자, 강력한 염증 유발 물질인 LPS를 대식세포에 처리하여 그 배양액을 중간엽 줄기세포에 처리하여 변화를 관찰하였다. LPS 배양액을 처리한 중간엽 줄기세포는 평활근 세포로 분화가 촉진되는 것을 확인하였으며, LPS 배양액에 존재하는 분화 유도 물질이 $PGF2{\alpha}$임을 확인하였다. 이에 본 연구결과를 통해 염증 상태에서 존재하는 중간엽 줄기세포는 평활근 세포로의 분화가 촉진되는 것을 확인하였다. 본 연구는 염증성 미세환경 내에 존재하는 중간엽 줄기세포가 평활근 세포로 분화가 유도됨을 확인하였고, 혈관 형성을 촉진하는데 영향을 미칠 수 있음을 제시한다.

• 한국축산식품학회지
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• 제40권5호
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• pp.852-859
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• 2020

The muscle stem cells of domestic animals are of interest to researchers in the food and biotechnology industries for the production of cultured meat. For producing cultured meat, it is crucial for muscle stem cells to be efficiently isolated and stably maintained in vitro on a large scale. In the present study, we aimed to optimize the method for the enrichment of pig muscle stem cells using a magnetic-activated cell sorting (MACS) system. Pig muscle stem cells were collected from the biceps femoris muscles of 14 d-old pigs of three breeds [Landrace×Yorkshire×Duroc (LYD), Berkshire, and Korean native pigs] and cultured in skeletal muscle growth medium-2 (SkGM-2) supplemented with epidermal growth factor (EGF), dexamethasone, and a p38 inhibitor (SB203580). Approximately 30% of total cultured cells were nonmyogenic cells in the absence of purification in our system, as determined by immunostaining for cluster of differentiation 56 (CD56) and CD29, which are known markers of muscle stem cells. Interestingly, following MACS isolation using the CD29 antibody, the proportion of CD56⁺/CD29⁺ muscle stem cells was significantly increased (91.5±2.40%), and the proportion of CD56 single-positive nonmyogenic cells was dramatically decreased. Furthermore, we verified that this method worked well for purifying muscle stem cells in the three pig breeds. Accordingly, we found that CD29 is a valuable candidate among the various marker genes for the isolation of pig muscle stem cells and developed a simple sorting method based on a single antibody to this protein.

• BMB Reports
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• 제48권11호
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• pp.595-596
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• 2015

Skeletal muscle exhibits a loss of muscle mass and function with age. Decreased regenerative potential of muscle stem/progenitor cells is a major underlying cause of sarcopenia. We analyzed microRNAs (miRNA) that are differentially expressed in young and old myoblasts, to identify novel intrinsic factors that play a degenerative role in aged skeletal muscle. miR-431, one of decreasing miRNAs in old myoblasts, improved the myogenic differentiation when overexpressed in old myoblast, but suppressed their myogenic capability in knockdowned young myoblasts. We found that miR-431 directly binds to 3` untranslated regions (UTR) of Smad4 mRNA, and decreases its expression. Given that SMAD4 is one of the downstream effectors of TGF-β, a well-known degenerative signaling pathway in myogenesis, the decreased miR-431 in old myoblast causes SMAD4 elevation, thus resulting in defective myogenesis. Exogenous expression of miR-431 greatly improved the muscle regeneration in the cardiotoxin-injured hindlimb muscle of old mice by reducing SMAD4 levels. Since the miR-431 seed sequence is conserved in human SMAD4 3'UTR, miR-431 regulates the myogenic capacity of human skeletal myoblasts in the same manner. Our results suggest that age-associated miR-431 is required for the maintenance of the myogenic capability in myoblasts, thus underscoring its potential as a therapeutic target to slow down muscle aging.

• Journal of Ginseng Research
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• 제42권1호
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• pp.116-121
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• 2018

Background: Black ginseng (BG) has greatly enhanced pharmacological activities relative to white or red ginseng. However, the effect and molecular mechanism of BG on muscle growth has not yet been examined. In this study, we investigated whether BG could regulate myoblast differentiation and myotube hypertrophy. Methods: BG-treated C2C12 myoblasts were differentiated, followed by immunoblotting for myogenic regulators, immunostaining for a muscle marker, myosin heavy chain or immunoprecipitation analysis for myogenic transcription factors. Results: BG treatment of C2C12 cells resulted in the activation of Akt, thereby enhancing hetero-dimerization of MyoD and E proteins, which in turn promoted muscle-specific gene expression and myoblast differentiation. BG-treated myoblasts formed larger multinucleated myotubes with increased diameter and thickness, accompanied by enhanced Akt/mTOR/p70S6K activation. Furthermore, the BG treatment of human rhabdomyosarcoma cells restored myogenic differentiation. Conclusion: BG enhances myoblast differentiation and myotube hypertrophy by activating Akt/mTOR/p70S6k axis. Thus, our study demonstrates that BG has promising potential to treat or prevent muscle loss related to aging or other pathological conditions, such as diabetes.

• BMB Reports
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• 제52권1호
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• pp.64-69
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• 2019

The loss of skeletal muscle, called sarcopenia, is an inevitable event during the aging process, and significantly impacts quality of life. Autophagy is known to reduce muscle atrophy caused by dysfunctional organelles, even though the molecular mechanism remains unclear. Here, we have discuss the current understanding of exercise-induced autophagy activation in skeletal muscle regeneration and remodeling, leading to sarcopenia intervention. With aging, dysregulation of autophagy flux inhibits lysosomal storage processes involved in muscle biogenesis. AMPK-ULK1 and the $FoxO/PGC-1{\alpha}$ signaling pathways play a critical role in the induction of autophagy machinery in skeletal muscle, thus these pathways could be targets for therapeutics development. Autophagy has been also shown to be a critical regulator of stem cell fate, which determines satellite cell differentiation into muscle fiber, thereby increasing muscle mass. This review aims to provide a comprehensive understanding of the physiological role of autophagy in skeletal muscle aging and sarcopenia.