• Title/Summary/Keyword: Chick myoblast

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Effects of $Ca^2+$ and Protein Kinase C on the Chick Myoblast Differentiation (Ca$^2+$ 및 Protein Kinase C가 배양한 계배근원세포의 분화에 미치는 영향)

  • 정기화;김세재;박정원;박영철;이정주
    • The Korean Journal of Zoology
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    • v.32 no.1
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    • pp.40-47
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    • 1989
  • Alteration of intracellular calcium ion Concentration by adding of either calcium ionophore A23187 or EGTA in culture medium at 24 hr after cell plating resulted in remarkable changes in the progression of differentiation of chick embryo myoblast. When separated myoblast proteins using two-dimensional gel electrophoresis, synthesis patterns of several proteins changed upon the addition of either A23187 or EGTA. Treatment of A23187 and calciumactivated neutral protease at 24 hr after initial plating caused an increase in the rate of fusion compared to control culture. However, EGTA inhibited the myoblast fusion to a marked degree. A23187 treated at 24hr also increased the activity of protein kinase C during the fusionprogressed period. It seems that intracellular calcium ion plays an important role in the myoblast differentiation in vitro together with the protein kinase C and calcium-activated neutral protease.

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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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The Presence in Embryo Extract of a Myotrophic Protein That Affects Proliferation and Fusion of Chick Embryonic Myoblasts in Culture (배양 계배 근원세포의 분화에 미치는 계배 추출물내 Myotrophic Protein의 영향)

  • 유병제;이창호;곽규봉;정진하;하두봉
    • The Korean Journal of Zoology
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    • v.31 no.3
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    • pp.207-217
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    • 1988
  • A myotrophic protein that seemed to he eseentiai for the hision of chick embryonic myoblasts in culture was isolated from chick embryo extrad and was found to be identical or at least similar to the iron-transporting protein, transferrin. Embryo extract seemed to contain, in addition to this myotrophic protein, a heat stable protein that inhibits the fusion of myoblasts. Iron seemed to he necessary for myoblasts to fuse and it was supposed that the role of the myotrophic protein m myoblast fusion is to supply iron to the cell. The numher of the myotrophic protein receptors on myoblast surface membrane decreased immediately after the start of myoblast fusion, supposedly due to the decreased need of iron after the fusion once commenced. It was estimated that endocytosis of myotrophic protein took about 10 minutes and one recycling about 2 hours. The accumulation of iron in myoblasts continued linearly with cultre time and endocytosis of the myotrophic protein occured at a constant rate.

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Identification of a Fusion-associated Protein in the Skeletal Myoblast Using Monoclonal Antibody (단일클론항체를 이용한 배양 계배 근원세포의 융합과 연관된 단백질의 확인)

  • Kim, Chons-Rak;Won
    • The Korean Journal of Zoology
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    • v.35 no.1
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    • pp.29-36
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    • 1992
  • The present study describes the production of monoclonal antibodies against cultured chick myoblast to pursue critical proteins in muscle cell fusion. Among a panel of monoclonal antibodies, three, Mll-3H 13, Mll-3Hl8 and Mll-3H35 were inhibited movblast fusion. A single 101-kDa antigen reactive with monoclonal antibody Mll-3H35 was detected by radioimmu-noprecipitation or by immunoblotting. During the course of myogenesis, the level of the protein remarkably decreased as the cells there differentiated. These results suggest that the protein platys a direct role in the process of myoblast fusion mechanism.

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The Effect of Muscle-Conditioned Medium on the Fusion of Chick Embryonic Myoblast Cells in Culture (배양 계배 근원세포의 융합에 미치는 Muscle-Conditioned Medium의 영향)

  • Ha, Doo-Bong;Yoo, Yung-Joon
    • The Korean Journal of Zoology
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    • v.27 no.3
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    • pp.151-164
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    • 1984
  • In order to investigate the mechanism of myoblast fusion during muscle differentiation in culture, the effect of muscle-conditioned medium on the fusion was studied and possible release from cultured myoblast cells of proteins which may be responsible for the promotion of myoblast fusion was analyzed. The muscle-conditioned medium showed a marked fusion-promoting activity in a dose-dependent fashion. THis fusion-promoting activity of the muscle-conditioned medium appeared to be due to the accumulation of at least two proteins which were released from the myoblast into the culture medium. These released proteins were analyzed by electrophoresis and autoradiography and found to have molecular weights of 45,000 and 65,000.

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Phosphorylation of Eukaryotic Elongation Factor 2 Can Be Regulated by Phosphoinositide 3-Kinase in the Early Stages of Myoblast Differentiation

  • Woo, Joo Hong;Kim, Hye Sun
    • Molecules and Cells
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    • v.21 no.2
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    • pp.294-301
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    • 2006
  • We have previously reported that phosphorylation of eukaryotic elongation factor 2 (eEF2) is related to the differentiation of chick embryonic muscle cells in culture. In the present study, we found that eEF2 phosphorylation declined shortly after induction of differentiation of L6 myoblasts, when the cells prepare for terminal differentiation by withdrawing from the cell cycle. This decrease in phosphorylation was prevented by inhibitors of phosphoinositide 3-kinase (PI3-kinase) that strongly inhibit myoblast differentiation. We hypothesized that PI3-kinase plays an important role in myoblast differentiation by regulating eEF2 phosphorylation in the early stages of differentiation. To test this hypothesis, myoblasts were synchronized at in $G_2/M$ and cultured in fresh differentiation medium (DM) or growth medium (GM). In DM the released cells accumulated in $G_0$/$G_1$ while in GM they progressed to S phase. In addition, cyclin D1 was more rapidly degraded in DM than in GM, and eEF2 phosphorylation decreased more. Inhibitors of PI3-kinase increased eEF2 phosphorylation, but PI3-kinase became more activated when eEF2 phosphorylation declined. These results suggest that the regulation of L6 myoblast differentiation by PI3-kinase is related to eEF2 phosphorylation.

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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Changes in the Cellular cGMP Levels and Guanylate Cyclase Activities during Chick Myoblast Fusion (근원세포 융합시 Cellular cGMP 수준과 Guanylate cyclase 활성의 변화)

  • 백미영;강만식
    • The Korean Journal of Zoology
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    • v.36 no.3
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    • pp.433-438
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    • 1993
  • In the previous paper (Choi et al., 1992), we found that a large but transient elevation in intracellular cGMP levels occur concomitant with the myoblast fusion. To establish the physiological significance of the elevation of cGMP levels, the change in guanylate cyclase activity dudng myoblast fusion and the correlation hetween various chemicals that may affect guanylate cyclase adivity and myoblast fusion were examined. Sodium nitroprusside, a nitric oxide-forming compound, induced a precocious fusion and increased guanylate cyclase activity compared to the control. Furthermore, L-NG-monomethyl arginine, specific inhibitor of L-arginine: nitric oxide synthase, inhibited the cell fusion in a dose-dependent manner, without affecting biochemical differentiation. On the basis of our present findings, we propose that the onset of myoblast fusion is somehow correlated with the rise in cellular cGMP levels that is regulated by the activation or inhibItIon of soluble guanylate cyclase, via as yet undefined mechanism but possibly through L-arginine: nitric oxide pathway.

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