• Title, Summary, Keyword: Myoblast

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Novel function of stabilin-2 in myoblast fusion: the recognition of extracellular phosphatidylserine as a "fuse-me" signal

  • Kim, Go-Woon;Park, Seung-Yoon;Kim, In-San
    • BMB Reports
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    • v.49 no.6
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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.

Inhibition of Myoblast Differentiation by Polyamine Depletion with Methylglyoxal Bis(guanylhydrazone)

  • Cho, Hwa-Jeong;Kim, Byeong-Gee;Kim, Han-Do;Kang, Ho-Sung;Kim, Chong-Rak
    • BMB Reports
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    • v.28 no.3
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    • pp.191-196
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    • 1995
  • The role of polyamines in skeletal myoblast differentiation was investigated using the polyamine metabolic inhibitor methylglyoxal bis(guanylhydrazone)(MGBG). Concentrations of intracellular free spermidine and spermine increased 2 to 2.5-fold at the onset of myoblast fusion. The systhesis of actin, and creatine kinase activity both dramatically increased during myotube formation. However, MGBG at a concentration of 0.5 mM not only abolished the increase of intracellular free polyamines, but also reduced cell fusion to almost half the level of untreated cells, without noticeable morphological alteration. The production of actin, and creatine kinase activity were almost completely abolished by MGBG. The inhibition of myoblast fusion by MGBG was partially recovered with 0.1 mM of spermidine or spermine added externally. Results indicate that polyamines are necessary for normal myoblast differentiation. Since the first indication of myoblast differentiation is alignment of muscle cells and membrane fusion of adjacent cells, and since polyamine depletion completely inhibited the synthesis of actin, which might be associted with membranes, polyamine might be involved in myoblast differentiation through membrane reorganization events.

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Effect of trichostatin A on NF-κB DNA binding activity and myogenesis in C2Cl2 skeletal muscle Precursor cell (C2C12 근육아세포에서 trichostatin A에 의한 NF-κB DNA 결합 활성과 근육발생에 미치는 영향)

  • 임운기;김경창;신혜자
    • Journal of Life Science
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    • v.12 no.1
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    • pp.55-60
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    • 2002
  • The differentiation of skeletal muscle precursor cells in culture is marked by the transcriptional activation of muscle-specific genes and the morphological differentiation of myoblast into multinucleate myotube. In this study, we examined the effect of TSA (Trichostatin A) on WF-kB DNA binding activity and muscle cell fusion in the process of myogenesis. Under TSA treatment, C2C12 myoblast could not fuse to myotube and its NF-kB DNA binding activity was also blocked. To investigate whether these phenomenons were affected by TSA in direct or not, differentiation media (DM) used to differentiate cells without TSA was concentrated and added to C2C12 myoblast with TSA simultaneously. C2C12 myoblast was fused to myotube and NF-kB DNA binding activity was recovered. These results suggest that TSA affects on the differentiation of myoblast, perhaps through several factors, by inhibiting myoblst fusion and blocking NF-kB DNA binding activity.

A Possible Role of Kainate Receptors in C2C12 Skeletal Myogenic Cells

  • Park, Jae-Yong;Han, Jae-Hee;Hong, Seong-Geun
    • 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.

Effects of Catecholamine on the Fusion of Chick Embryo Myoblasts in vitro (鷄胚筋原細胞의 融合에 미치는 카테콜아민의 影響)

  • Kang, Man-Sik;Ha, Doo-Bong;Lee, Chung-Choo;Park, Yung-Chul;Hyockman Kwon
    • The Korean Journal of Zoology
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    • v.27 no.2
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    • pp.73-84
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    • 1984
  • In order to investigate the effect of neurotransmitter on myoblast differentiation in vitro, the effects of dopamine and epinephrine on myoblast fusion and on the intracellular cAMP level in cultured myoblasts were examined. Dopamine $(3\\times10^{-5}M)$ and epinephrine $(3\\times10^{-5}M)$, when added at 34 hr after cell plating, markedly inhibited myoblast fusion, and dopamine was more potent than epinephrine. Both dopamine and epinephrine had no effect on intracellular cAMP level. At the same time, exogeneous dbcAMP, $PGE_1$, and aspirin were used to examine whether cAMP is involved in myoblast differentiation. dbcAMP $(1\\times10^{-4}M)$ inhibited myoblast fusion, whereas $PGE_1 (3\\times10^{-6}M)$ had no inhibitory effect, rather enhancing myoblast fusion. Aspirin, an inhibitor of PG synthetase, was shown to inhibit myoblast fusion. Possible mechanism by which dopamine or epinephrine at a specific concentration used inhibits myoblast fusion is discussed.

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Alteration in the Transferrin Receptor during the Chick Myoblast Fusion in Culture (계배 근원세포의 융합에 따른 Transferrin 수용체의 변화)

  • 이창호;유병제;전영주;정진하;하두봉
    • The Korean Journal of Zoology
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    • v.32 no.2
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    • pp.163-175
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    • 1989
  • Transferrin (Tf) has been known to exert profound effect on the myoblast differentiation in uirto. Therefore, the changes in the amount and affinity of the Tf receptor would accompany the myoblast differentiation. To investigate this possibility, we exarnined the afteration pattern in the level of the Tf receptor during the myoblast fusion. The level of Tf receptor was assayed by measuring the bound 125 I-Tf onto the surface of cultured myoblasts, and it was known that the level of Tf receptor reached the maximum at about 12 hr before the initi ation of the myoblast fusion and decreased as the differentiation proceeded, and that the affinity of Tf receptor to Tf was also decreased. In addition, various inhibitiors of the myoblast fusion also influenced the level of the Tf receptor. Accroding to these results, it is postulated that the level of Tf receptor is highly regulated during the myoblast differentiation.

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HDAC11 Inhibits Myoblast Differentiation through Repression of MyoD-Dependent Transcription

  • Byun, Sang Kyung;An, Tae Hyeon;Son, Min Jeong;Lee, Da Som;Kang, Hyun Sup;Lee, Eun-Woo;Han, Baek Soo;Kim, Won Kon;Bae, Kwang-Hee;Oh, Kyoung-Jin;Lee, Sang Chul
    • Molecules and Cells
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    • v.40 no.9
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    • pp.667-676
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    • 2017
  • Abnormal differentiation of muscle is closely associated with aging (sarcopenia) and diseases such as cancer and type II diabetes. Thus, understanding the mechanisms that regulate muscle differentiation will be useful in the treatment and prevention of these conditions. Protein lysine acetylation and methylation are major post-translational modification mechanisms that regulate key cellular processes. In this study, to elucidate the relationship between myogenic differentiation and protein lysine acetylation/methylation, we performed a PCR array of enzymes related to protein lysine acetylation/methylation during C2C12 myoblast differentiation. Our results indicated that the expression pattern of HDAC11 was substantially increased during myoblast differentiation. Furthermore, ectopic expression of HDAC11 completely inhibited myoblast differentiation, concomitant with reduced expression of key myogenic transcription factors. However, the catalytically inactive mutant of HDAC11 (H142/143A) did not impede myoblast differentiation. In addition, wild-type HDAC11, but not the inactive HDAC11 mutant, suppressed MyoD-induced promoter activities of MEF2C and MYOG (Myogenin), and reduced histone acetylation near the E-boxes, the MyoD binding site, of the MEF2C and MYOG promoters. Collectively, our results indicate that HDAC11 would suppress myoblast differentiation via regulation of MyoD-dependent transcription. These findings suggest that HDAC11 is a novel critical target for controlling myoblast differentiation.

Setdb1 Is Required for Myogenic Differentiation of C2C12 Myoblast Cells via Maintenance of MyoD Expression

  • Song, Young Joon;Choi, Jang Hyun;Lee, Hansol
    • Molecules and Cells
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    • v.38 no.4
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    • pp.362-372
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    • 2015
  • Setdb1, an H3-K9 specific histone methyltransferase, is associated with transcriptional silencing of euchromatic genes through chromatin modification. Functions of Setdb1 during development have been extensively studied in embryonic and mesenchymal stem cells as well as neurogenic progenitor cells. But the role of Sedtdb1 in myogenic differentiation remains unknown. In this study, we report that Setdb1 is required for myogenic potential of C2C12 myoblast cells through maintaining the expressions of MyoD and muscle-specific genes. We find that reduced Setdb1 expression in C2C12 myoblast cells severely delayed differentiation of C2C12 myoblast cells, whereas exogenous Setdb1 expression had little effect on. Gene expression profiling analysis using oligonucleotide microarray and RNA-Seq technologies demonstrated that depletion of Setdb1 results in downregulation of MyoD as well as the components of muscle fiber in proliferating C2C12 cells. In addition, exogenous expression of MyoD reversed transcriptional repression of MyoD promoter-driven luciferase reporter by Setdb1 shRNA and rescued myogenic differentiation of C2C12 myoblast cells depleted of endogenous Setdb1. Taken together, these results provide new insights into how levels of key myogenic regulators are maintained prior to induction of differentiation.

Investigation of the effect of Terminalia chebula fruit extract and its active ingredient, gallic aicd on muscle differentiation (가자(訶子) 추출물과 그 유효성분 갈산이 근분화에 미치는 영향)

  • Cheon, Seonghye;Lee, Hyo Seong;Han, Hyo Sang;Kim, Kee Kwang
    • The Korea Journal of Herbology
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    • v.34 no.2
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    • pp.59-66
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    • 2019
  • Objectives : Decrease in muscle mass and loss of muscle function due to aging are associated with various diseases. As interest in healthy aging increases, efforts to prevent and treat muscle hypoxia as an illness are increasing. Considering the physical limitations, a pharmacologic approach to the treatment of myopenia is needed. Methods : Terminalia chebula Rets has a wide range of pharmacological effects and is used as a medicinal product in traditional medicine. However, the drug effect on the treatment of muscle disorders has not been revealed. The purpose of this study was to evaluate the value of water extract of Terminalia chebula (WETC) as a therapeutic agent to relieve symptoms of muscle hypoxia. Results : WETC showed strong radical scavenging ability. In addition, WETC increased cell activity of myoblast, and we observed that WETC induces myoblast differentiation by immunoblot analysis using differentiation protein markers as well as cell morphology of myoblast. Based on these results, we examined the effect of chebulic acid, chebulagic acid, gallic acid, geraniin, and punicalagin on cell activity and differentiation of myoblasts. Gallic acid significantly increased cell activity of myoblast, and it was found to be an effective substance which not only induces myoblast differentiation but also promotes proliferation. Conclusions : We suggest that the WETC with antioxidant effect and its indicator gallic acid on cell activity, proliferation and differentiation of myoblast can be studied and developed as a food and medicine for prevention and treatment of various muscle diseases.

Regulated Expression of Nebulin by Transfection of Green Fluorescent Protein-Tagged Nebulin Fragments in Cultured Chicken Myoblast

  • Park, Su-Jung;Kim, Ji-Hee;Ko, Han-Suk;Kim, Chong-Rak;Kim, Han-Do;Kang, Ho-Sung
    • Biomedical Science Letters
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    • v.7 no.4
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    • pp.167-172
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    • 2001
  • Nebulin is an approximately 700 kDa filamentous protein in vertebrate skeletal muscle. It binds to the Z line and also binds side-by-side to the entire thin actin filament in a sarcomere. The correlation of nebulin size with thin filament length have led to the suggestion that nebulin acts as a molecular ruler for the length of thin filaments. The C-terminal part of human nebulin is anchored in the sarcomeric Z-disk and contains an SH3 domain. SH3 domains have been identified in an ever-increasing number of proteins important for a wide range of cellular processes, from signal transduction to cytoskeleton assembly and membrane localization. However, the exact physiological role of SH3 domains remains, in many cases, unclear. To explore the role of nebulin SH3 in the cytoskeletal rearrangement that accompanies myoblast differentiation, we transfected sense and antisense nebulin SH3 domain fused to enhanced green fluorescent protein in myoblast. Cells expressing nebulin SH3 fragment showed decrease of cell-cell adhesion, and cells transfected with antisense nebulin SH3 gene showed a rounded cell morphology and loss of cell-matrix adhesion. No alteration in cell shape and differentiation were observed in control cells expressing enhanced green fluorescent protein. Perturbation of nebulin altered the cell shape and disrupted cell adhesion in myoblast, demonstrating that nebulin can affect cytoskeleton rearrangement.

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