• 운동영양학회지
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• 제15권4호
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• pp.153-161
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• 2011

The maintenance of skeletal muscle mass is very important for the prevention of life style-related diseases and the improvement of quality of life. It is well-known that resistance exercise and nutrition (especially amino acids) are the most effective interventions for maintaining skeletal muscle mass. It has been reported that many molecules are involved in the regulation of protein synthesis in response to resistance exercise and nutrition. Understanding the molecular mechanisms regulating muscle protein synthesis is crucial for the development of appropriate interventions. The role of intracellular signaling pathways through the mammalian target of rapamycin (mTOR), a serine/threonine protein kinase in the regulation of muscle protein synthesis, has been extensively investigated for these years. Control of protein synthesis by mTOR is mediated through phosphorylation of downstream targets that modulate translation initiation and elongation step. In contrast, upstream mediators regulating mTOR and protein synthesis in response to resistance exercise and amino acid still needed to be determined. In this brief review, we discuss the current progress of intracellular mechanisms for exercise- and amino acid-induced activation of mTOR pathways and protein synthesis in skeletal muscle.

• 약학회지
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• 제27권2호
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• pp.109-116
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• 1983

The effect of protein constituents of six-year old fresh Panax ginseng root on chick embryonic brain, spinal cord and skeletal muscle dissociation cultures was studied. The protein constituents showed the enhancing effect on cultured brain, spinal cord and skeletal muscle cells. The neurite formation from brain and spinal cord cells and the outgrowth of neurite seemed to be enhanced by almost all of the protein constituents employed for this study. The maturation of skeletal muscle cells was stimulated by the protein constituents. This enhancing effect of the protein constituents was more vivid when brain, spinal cord and skeletal muscle cells were cultured with a medium which did not contain chick embryonic extracts known as an essential component for primary cell culture. The protein fraction having molecular weight range of 1,000 to 5,000 out of all the protein fractions employed for this study showed the most stimulatory effect on cultured brain, spinal cord and skeletal muscle cells.

• Journal of Microbiology and Biotechnology
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• 제34권3호
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• pp.495-505
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• 2024

Gromwell (Lithospermum erythrorhizon, LE) can mitigate obesity-induced skeletal muscle atrophy in C2C12 myotubes and high-fat diet (HFD)-induced obese mice. The purpose of this study was to investigate the anti-skeletal muscle atrophy effects of LE and the underlying molecular mechanism. C2C12 myotubes were pretreated with LE or shikonin, and active component of LE, for 24 h and then treated with 500 μM palmitic acid (PA) for an additional 24 h. Additionally, mice were fed a HFD for 8 weeks to induced obesity, and then fed either the same diet or a version containing 0.25% LE for 10 weeks. LE attenuated PA-induced myotubes atrophy in differentiated C2C12 myotubes. The supplementation of LE to obese mice significantly increased skeletal muscle weight, lean body mass, muscle strength, and exercise performance compared with those in the HFD group. LE supplementation not only suppressed obesity-induced skeletal muscle lipid accumulation, but also downregulated TNF-α and atrophic genes. LE increased protein synthesis in the skeletal muscle via the mTOR pathway. We observed LE induced increase of mitochondrial biogenesis and upregulation of oxidative phosphorylation related genes in the skeletal muscles. Furthermore, LE increased the expression of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha and the phosphorylation of adenosine monophosphate-activated protein kinase. Collectively, LE may be useful in ameliorating the detrimental effects of obesity-induced skeletal muscle atrophy through the increase of protein synthesis and mitochondrial biogenesis of skeletal muscle.

• 대한한의학방제학회지
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• 제24권3호
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• pp.153-161
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• 2016

Chronic alcoholic myopathy is one of the most common skeletal muscle disorders. It is characterized by a reduction in the entire skeletal musculature, skeletal muscle weakness, and difficulties in gait. Patients with alcoholic hepatitis and cirrhosis have severe muscle loss that contributes to worsening outcome. Although the myopathy selectively affects Type II (fast twitch, glycolytic, anaerobic) skeletal muscle fibers, total skeletal musculature is reduced. The severity of the muscle atrophy is proportional to the duration and amount of alcohol consumed and leads to decreased muscle strength. The mechanisms for the myopathy are generally unknown but it is not due to overt nutritional deficiency, nor due to either neuropathy or severe liver disease. Skeletal muscle mass and protein content are maintained by a balance between protein synthesis and breakdown and in vivo animal models studies have shown that ethanol inhibits skeletal muscle protein synthesis. Daekumeumja is a traditional Korean medicine that is widely employed to treat various alcohol-induced diseases. Muscle diseases are often related to liver diseases and conditions. The main objective of this study was to assess that Daekumeumja extract could have protective effect against alcoholic myopathy in a Sprague-Dawley rat model. Rats were orally given 25% ethanol (5ml/kg, body weight) for 8 weeks. After 30 minutes, rats were administrated with Daekumeumja extract. Controls were similarly administrated with the vehicle alone. The weights of gastrocnemius, soleus and plantaris muscles were assessed and the morphologic changes of gastrocnemius and plantaris muscles were also assessed by hematoxylin and eosin staining. In results, The muscles from ethanol treated rats displayed a significant reduction in muscle weight and average cross section area compared to Normal group. Daekumeumja extract treated group showed increased muscle weight and muscle fiber compared to the ethanol treated group. It was concluded that Daekumeumja extract showed ameliorating effects on chronic alcohol myopathy in skeletal muscle.

• 대한의생명과학회지
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• 제16권4호
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• pp.207-212
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• 2010

Archivillin, a muscle-specific isoform of supervillin, is a component of the costameric cytoskeleton of muscle cells. The purpose of this study was to determine which protein in the skeletal muscle collaborates with archvillin C-terminus. For this purpose, a yeast two-hybrid screening of human skeletal muscle cDNA library was performed using the C-terminal region of archvillin as bait. This study shows that seven human skeletal muscle proteins, namely, nebulin, xeplin, archvillin, GAPDH, TOX4, PITRM1, and YME1L1 interact with archvillin C-terminus. Especially, xeplin is a newly discovered protein interacts with archvillin C-terminus. These results indicate that archvillin C-terminus acts as a bridge between nebulin and xeplin at costameres. Archvillin C-terminal region interacts with nebulin C-terminal region at Z-discs and interacts with xeplin at the vicinity of sarcolemma. I propose that these interactions may contribute to formation of costameric structure and muscle contraction.

• Perspectives in Nursing Science
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• 제2권1호
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• pp.19-36
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• 2005

Muscle atrophy is defined as a decrease in muscle mass, cross-sectional area, and myofibrillar protein content. Causes inducing muscle atrophy may be inactivity, denervation, undernutrition and steroid. Inactivity may decrease protein synthesis and increase protein breakdown of skeletal muscle. The muscle atrophy due to inactivity was induced by bed rest, hindlimb suspension, cast, total hip replacement arthroplasty, anterior cruciate ligament reconstruction. Denervated atrophy may be induced by the loss of innervation from lower motor neuron. The atrophy was apparent in the lower limb of hemiplegic patients following ischemic stroke and in the hindlimb of ischemic stroke rats. Protein breakdown of skeletal muscle in the undernourished state results in muscle atrophy. The atrophy due to undernutrition was evident in cancer and leukemia patients and in the undernourished rats. Steroids have been used to treat allergies, inflammatory diseases, autoimmune diseases and to inhibit immune function following transplantation. Steroids may induce muscle atrophy by protein breakdown of skeletal muscle. Muscle Physiology Laboratoryat College of Nursing, Seoul National University proved that dexamethasone may induce hindlimb muscle atrophy in rats and exercise and DHEA may attenuate hindlimb muscle atrophy induced by the steroid in rats. Nurses working with patients undergoing steroid treatment need to be cognizant of steroid induced muscle atrophy. They need to assess whether muscle atrophy is being occurred during and after the steroid treatment. Moreover, they need to apply exercise and DHEA to the patients undergoing steroid treatment in order to attenuate the steroid induced muscle atrophy.

• 생약학회지
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• 제21권3호
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• pp.210-216
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• 1990

Effects of the protein fraction of Panax ginseng on chicken embryonic skeletal muscle cells cultured with a decfiient medium were studied. The protein fraction was further fractionated into four groups according to the molecular weight; larger than 10,000 dalton(fraction A), between 5,000 and 10,000 dalton(fraction B), between 1,000 and 5,000 dalton(fraction C), between 500 and 1,000 dalton(fraction D). According to the microscopic observation, all four protein fractions at the concentration of $10{\sim}100{\;}{\mu}g/ml$ showed the tendency to stimulate the growth and differentiation of the muscle cells. The activity of acetylcholinesterase in muscle cells was significantly elevated by the protein fraction A at the concentration of $100{\mu}{\;}g/ml$. Protein fractions B,C and D significantly enhanced the synthesis of RNA in the muscle cells. The synthesis of DNA in muscle cells was significantly enhanced by protein fractions A,B and C.

• Journal of Acupuncture Research
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• 제31권1호
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• pp.7-21
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• 2014

Objectives : To observe the regenerative effects of indirect moxibustion, a traditional Korean medical treatment on skeletal muscles using mouse model of skeletal muscle adiposity. Methods : Twenty seven ICR male mice were randomly assigned into Intact control(n=3), glycerol treatment together without moxibustion(n=12), and glycerol treatment together with moxibustion (n=12) groups. Mice of glycerol treatment groups were injected with 50 ${\mu}l$ DW(distilled water) containing 50 % of glycerol into the two tibialis anterior. After injection, moxibustion was applied at 'Shenshu'($BL_{23}$) and 'Zusanli'($ST_{36}$) acupoints three times per each session, every days for twelve days(total 12 treatments). Phospho-Erk1/2, Myostatin protein levels were analyzed by western blotting and immunofluo-rescence staining techniques for tissues of the tibialis anterior muscle. Smad, phospho-Smad were analyzed by immunofluorescence staining. Results : 1. Histological analysis of sections from injected TA muscles showed that glycerol induced rapidly muscle necrosis, with a maximum at day 3. 6 days and 9 days after injection, muscle was regenerating. 2. According to western blotting and immunofluorescence staining, phospho-Erk1/2 protein signals in glycerol treatment with moxibustion group were stronger compared to Intact and glycerol treatment without moxibustion group. 3. According to western blotting and immunofluorescence staining, myostatin protein signals in glycerol treatment without moxibustion group were stronger compared to Intact and glycerol treatment with moxibustion group. 4. According to immunofluorescence staining, Smad protein signals in glycerol treatment without moxibustion group were stronger compared to Intact and glycerol treatment with moxibustion group. 5. According to immunofluorescence staining, phospho-Smad protein signals in glycerol treatment without moxibustion group were stronger compared to Intact and glycerol treatment with moxibustion group. Conclusions : These results confirm that indirect moxibustion of 'Shenshu'($BL_{23}$) and 'Zusanli'($ST_{36}$) influences muscle regeneration in mouse models of skeletal muscle adiposity. Further discussion, and the establishment of moxibustion mechanism will prompt clinical application of moxibustion.

• Asian-Australasian Journal of Animal Sciences
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• 제18권1호
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• pp.133-140
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• 2005

Although amino acids are substrates for the synthesis of proteins and nitrogen-containing compounds, it has become more and more clear over the years that these nutrients are also extremely important as regulators of body protein turnover. The branched-chain amino acids (BCAAs) together or simply leucine alone stimulate protein synthesis and inhibit protein breakdown in skeletal muscle. However, it was only recently that the mechanism(s) involved in the regulation of protein turnover by BCAAs has begun to be defined. The acceleration of protein synthesis by these amino acids seems to occur at the level of peptide chain initiation. Oral administration of leucine to food-deprived rats enhances muscle protein synthesis, in part, through activation of the mRNA binding step of translation initiation. Despite our knowledge of the induction of protein synthesis by BCAAs, there are few studies on the suppression of protein degradation. The recent findings that oral administration of leucine rapidly reduced $N^{\tau}$-methylhistidine (3-methylhistidine; MeHis) release from isolated muscle, an index of myofibrillar protein degradation, indicate that leucine suppresses myofiblilar protein degradation. The details of the molecular mechanism by which leucine inhibits proteolysis is just beginning to be elucidated. The purpose of this report was to review the current understanding of how BCAAs act as regulators of protein turnover.

• Animal cells and systems
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• 제16권6호
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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 [$Ca^{2+}$].