• Title, Summary, Keyword: Skeletal muscle growth

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Insulin-Like Growth Factor-I-Induced Androgen Receptor Activation Is Mediated by the PI3K/Akt Pathway in C2C12 Skeletal Muscle Cells

  • Lee, Won Jun
    • Molecules and Cells
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    • v.28 no.5
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    • pp.495-499
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    • 2009
  • Although insulin-like growth factor-I (IGF-I) and androgen receptor (AR) are well known effectors of skeletal muscle, the molecular mechanism by which signaling pathways integrating AR and IGF-I in skeletal muscle cells has not been previously examined. In this study, the role of PI3K/Akt on IGF-I-induced gene expression and activation of AR in skeletal muscle cells was investigated. C2C12 cells were treated with IGF-I in the absence or presence of inhibitors of PI3K/Akt pathway (LY294002 and Wortmannin). Inhibition of the PI3K/Akt pathway with LY294002 or Wortmannin led to a significant decrease in IGF-I-induced AR phosphorylation and total AR protein expression. Furthermore, IGF-I-induced AR mRNA and skeletal ${\alpha}-actin$ mRNA were blocked by LY294002 or Wortmannin. Confocal images showed that IGF-I-induced AR translocation from cytosol to nucleus was inhibited significantly in response to treatment with LY294002 or Wortmannin. The present results suggest that modulating effect of IGF-I on AR gene expression and activation in C2C12 mouse skeletal muscle cells is mediated at least in part by the PI3K/Akt pathway.

Review of Effect of the Mechanical Stress on Muscle (근육에 대한 역학적 스트레스의 영향)

  • Kang, Jong-Ho;Kim, Jin-Sang
    • PNF and Movement
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    • v.6 no.2
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    • pp.51-57
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    • 2008
  • Purpose : Mechanical stress activates signaling cascades and leading to a specific response of a network of signaling pathways. The purpose of this study is to review the effect of mechanical stress-induced adaptation in skeletal muscle involves a biological mechanisms. Methods : This is literature study with Pubmed, Medline and books. Results : Skeletal muscle tissue demonstrates a malleability and may adjust its metabilic response, vascularization and neuromuscular characteristic makeup in response to alteration in functional demands. The adaptation in skeletal muscle involoves a multitude of signalling mechanisms related with insuline-like growth factor, vascular endothelial growth factor, neurotrophins. Conclusions : The identification of the basic relationships underlying the malleability of skeletal muscle tissue is likely to be of relevance for our understanding with PNF technique.

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Factors Influencing Satellite Cell Activity during Skeletal Muscle Development in Avian and Mammalian Species

  • Nierobisz, Lidia S;Mozdziak, Paul E
    • Asian-Australasian Journal of Animal Sciences
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    • v.21 no.3
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    • pp.456-464
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    • 2008
  • Avian and mammalian skeletal muscles exhibit a remarkable ability to adjust to physiological stressors induced by growth, exercise, injury and disease. The process of muscle recovery following injury and myonuclear accretion during growth is attributed to a small population of satellite cells located beneath the basal lamina of the myofiber. Several metabolic factors contribute to the activation of satellite cells in response to stress mediated by illness, injury or aging. This review will describe the regenerative properties of satellite cells, the processes of satellite cell activation and highlight the potential role of satellite cells in skeletal muscle growth, tissue engineering and meat production.

Diversity of contractile properties in skeletal muscle fibers (골격근 섬유의 수축성 특성의 다양성)

  • Kim, Sik-hyun
    • PNF and Movement
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    • v.2 no.1
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    • pp.35-47
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    • 2004
  • Purpose : The purpose of this article was to review the literature on contractile properties of skeletal muscle with reference to its molecular and functional diversity. Method : This review outlines scientific findings regarding different contractile properties in skeletal muscle fibers, and discusses their involvement in functional diversity. Result & Conclusions: Muscle fibers possess distinct mechanical and energetic properties. Myosis, one of the primary contractile muscle proteins, displays structural, functional variability and plays the role of the molecular motor of muscle contraction. Muscle satellite cells are normally mitotically quiescent, but initiate proliferation and give rise to daughter myogenic precursor cells as required for the postnatal growth and regeneration of adult muscle. Passive extensibility is an important component of total muscle function because it allows for the maximal length of skeletal muscles. Proprioceptive neuromuscular facilitation(PNF) stretching can help to restore or improve flexibility and coordination, thereby improving overall muscle function.

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The role of sex steroid hormones in the pathophysiology and treatment of sarcopenia

  • Kim, Yong Jin;Tamadon, Amin;Park, Hyun Tae;Kim, Hoon;Ku, Seung-Yup
    • Osteoporosis and Sarcopenia
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    • v.2 no.3
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    • pp.140-155
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    • 2016
  • Sex steroids influence the maintenance and growth of muscles. Decline in androgens, estrogens and progesterone by aging leads to the loss of muscular function and mass, sarcopenia. These steroid hormones can interact with different signaling pathways through their receptors. To date, sex steroid hormone receptors and their exact roles are not completely defined in skeletal and smooth muscles. Although numerous studies focused on the effects of sex steroid hormones on different types of cells, still many unexplained molecular mechanisms in both skeletal and smooth muscle cells remain to be investigated. In this paper, many different molecular mechanisms that are activated or inhibited by sex steroids and those that influence the growth, proliferation, and differentiation of skeletal and smooth muscle cells are reviewed. Also, the similarities of cellular and molecular pathways of androgens, estrogens and progesterone in both skeletal and smooth muscle cells are highlighted. The reviewed signaling pathways and participating molecules can be targeted in the future development of novel therapeutics.

The role of calpain in skeletal muscle

  • Pandurangan, Muthuraman;Hwang, Inho
    • Animal cells and systems
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    • v.16 no.6
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    • pp.431-437
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    • 2012
  • Calpains are a class of proteins that belong to the calcium-dependent, non-lysosomal cysteine proteases. There are three major types of calpains expressed in the skeletal muscle, namely, ${\mu}$-calpain, m-calpain, and calpain 3, which show proteolytic activities. Skeletal muscle fibers possess all three calpains, and they are $Ca^{2+}$-dependent proteases. The functional role of calpains was found to be associated with apoptosis and myogenesis. However, calpain 3 is likely to be involved in sarcomeric remodeling. A defect in the expression of calpain 3 leads to limb-girdle muscular dystrophy type 2A. Calpain 3 is found in skeletal muscle fibers at the N2A line of the large elastic protein, titin. A substantial proportion of calpain 3 is activated 24 h following a single bout of eccentric exercise. In vitro studies indicated that calpain 3 can be activated 2-4 fold higher than normal resting cytoplasmic [$Ca^{2+}$]. Characterization of the calpain system in the developing muscle is essential to explain which calpain isoforms are present and whether both ${\mu}$-calpain and m-calpain exist in differentiating myoblasts. Information from such studies is needed to clarify the role of the calpain system in skeletal muscle growth. It has been demonstrated that the activation of ubiquitous calpains and calpain 3 in skeletal muscle is very well regulated in the presence of huge and rapid changes in intracellular [$Ca^{2+}$].

Developmental Proteomic Profiling of Porcine Skeletal Muscle during Postnatal Development

  • Kim, Nam-Kuk;Lim, Jong-Hyun;Song, Min-Jin;Kim, Oun-Hyun;Park, Beom-Young;Kim, Myung-Jick;Hwang, In-Ho;Lee, Chang-Soo
    • Asian-Australasian Journal of Animal Sciences
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    • v.20 no.10
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    • pp.1612-1617
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    • 2007
  • In this study, we have compared the skeletal muscle proteome at various stages of porcine postnatal development. Korean native pigs were divided into five postnatal stages of 30, 70, 130, 170 and 300 d and their loin muscles were analyzed for muscle proteome by using two-dimensional electrophoresis and mass spectrometry. We found 5 proteins showing a consistent pattern during skeletal muscle growth. Four proteins were identified as myosin light chain 1 slow-twitch (MLC1sa) isoform, troponin T, triosephosphate isomerase (TIP) and DJ-1 protein. The remaining protein was not identified. Two muscle fiber proteins of MLC1sa isoform and troponin T showed a high expression level at an early postnatal stage and then their levels were decreased markedly during growth stages. On the other hand, the expression of TIP and DJ-1 protein, which are well known as catalysis enzyme and antioxidant-related protein, respectively, were linearly increased during growth stages. Thus, the stage-related muscle proteins may be useful as parameters for understanding the developmental characteristics of biochemical and physiological properties in Korean native pig skeletal muscle.

Structure and Expression of the Chicken Myostatin Gene

  • Kim, Jin-Nam;Moon, Je-Sung;Lee, Eun-Young;Hwang, Kyu-Choon;Tae Hun;Kim, Ki-Dong;Han, Jae-Yong
    • Proceedings of the Korea Society of Poultry Science Conference
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    • pp.78-80
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    • 2000
  • A new murine TGF-$\beta$ family member, myostatin(growth/differentiation factor-8) is expressed specifically in developing and adult skeletal muscle and may be a negative regulator of skeletal muscle development. This study aims at characterization and identification of genomic organization of chicken myostatin gene. In thi study, we identified the genomic organization and sequence of chicken myostatin gene. Results of RT-PCR and Northern blots from various tissues showed different mRNA expression levels in developmental stages of chick embryos and demonstrated strong expression of myostatin mRNA in skeletal muscle. These facts suggest that chicken myostatin gene would play an important role not only in skeletal muscle cell but also in other tissues.

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Changes in expression of the autophagy-related genes microtubule-associated protein 1 light chain 3β and autophagy related 7 in skeletal muscle of fattening Japanese Black cattle: a pilot study

  • Nakanishi, Tomonori;Tokunaga, Tadaaki;Ishida, Takafumi;Kobayashi, Ikuo;Katahama, Yuta;Yano, Azusa;Erickson, Laurie;Kawahara, Satoshi
    • Asian-Australasian Journal of Animal Sciences
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    • v.32 no.4
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    • pp.592-598
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    • 2019
  • Objective: Autophagy is a bulk degradation system for intracellular proteins which contributes to skeletal muscle homeostasis, according to previous studies in humans and rodents. However, there is a lack of information on the physiological role of autophagy in the skeletal muscle of meat animals. This study was planned as a pilot study to investigate changes in expression of two major autophagy-related genes, microtubule-associated protein 1 light chain $3{\beta}$ (MAP1LC3B) and autophagy related 7 (ATG7) in fattening beef cattle, and to compare them with skeletal muscle growth. Methods: Six castrated Japanese Black cattle (initial body weight: $503{\pm}20kg$) were enrolled in this study and fattened for 7 months. Three skeletal muscles, M. longissimus, M. gluteus medius, and M. semimembranosus, were collected by needle biopsy three times during the observation period, and mRNA levels of MAP1LC3B and ATG7 were determined by quantitative reverse-transcription polymerase chain reaction. The expression levels of genes associated with the ubiquitin-proteasome system, another proteolytic mechanism, were also analyzed for comparison with autophagy-related genes. In addition, ultrasonic scanning was repeatedly performed to measure M. longissimus area as an index of muscle growth. Results: Our results showed that both MAP1LC3B and ATG7 expression increased over the observation period in all three skeletal muscles. Interestingly, the increase in expression of these two genes in M. longissimus was highly correlated with ultrasonic M. longissimus area and body weight. On the other hand, the expression of genes associated with the ubiquitin-proteasome system was unchanged during the same period. Conclusion: These findings suggest that autophagy plays an important role in the growth of skeletal muscle of fattening beef cattle and imply that autophagic activity affects meat productivity.

Insulin-like Growth Factor-I Modulates BDNF Expression by Inhibition of Histone Deacetylase in C2C12 Skeletal Muscle Cells (C2C12 골격근 세포에서 히스톤 탈 아세틸 효소의 억제가 인슐린 유사성장인자(IGF-I)에 의한 BDNF 발현 조절에 미치는 영향)

  • Kim, Hye Jin;Lee, Won Jun
    • Journal of Life Science
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    • v.27 no.8
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    • pp.879-887
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    • 2017
  • It is well established that brain-derived neurotrophic factor (BDNF) is expressed not only in the brain but also in skeletal muscle, and is required for normal neuromuscular system function. Histone deacetylases (HDACs) and insulin-like growth factor-I (IGF-I) are potent regulators of skeletal muscle myogenesis and muscle gene expression, but the mechanisms of HDAC and IGF-I in skeletal muscle-derived BDNF expression have not been examined. In this study, we examined the effect of IGF-I and suberoylanilide hydroxamic acid (SAHA), a pan-HDAC inhibitor, on BDNF induction. Proliferating or differentiating C2C12 skeletal muscle cells were treated with increasing concentrations (0-50 ng/ml) of IGF-I in the absence or presence of $5{\mu}M$ SAHA for various time periods (3-24 hr). Treatment of C2C12 cells with IGF-I resulted in a dose- and time-dependent decrease in BDNF mRNA expression. However, inhibition of HDAC led to a significant increase in the expression of BDNF mRNA levels. In addition, immunocytochemistry revealed high BDNF protein levels in undifferentiated C2C12 skeletal muscle cells, whether untreated, IGF-I-treated, or exposed to SAHA. These results represent the first evidence that IGF-I can suppress the mRNA and protein expression of BDNF; conversely, SAHA attenuates the effects of IGF-I. Consequently, SAHA upregulates BDNF expression in C2C12 skeletal muscle cells.