• The Journal of Korean Physical Therapy
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• 제20권1호
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• pp.57-65
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• 2008

Purpose: Heat shock proteins (HSPs) are a group of proteins that are activated when cells are exposed to a variety of environmental stresses, such as infection, inflammation, exposure to toxins, starvation, hypoxia, brain injury, or water deprivation. The activation of HSPs by environmental stress plays a key role in signal transduction, including cytoprotection, molecular chaperone, anti-apoptotic effect, and anti-aging effects. However, the precise mechanism for the action of small HSPs, such as HSP27 and mitogen-activated protein kinases (MAPKs: extracellular-regulated protein kinase 1/2 (ERK1/2), p38MAPK, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), is not completely understood, particularly in application of cell stimulators including platelet-derived growth factor (PDGF), angiotensin II (AngII), tumor necrosis factor $\alpha$ (TNF$\alpha$), and $H_2O_2$. This study examined the relationship between stimulators-induced enzymatic activity of HSP27 and MAPKs from rat smooth and skeletal muscles. Methods: 2-dimensional electrophoresis (2DE) and matrix assisted laser desorption ionizationtime-of-flight/time-of-flight (MALDI-TOF/TOF) analysis were used to identify HSP27 from the intact vascular smooth and skeletal muscles. Three isoforms of HSP27 were detected on silver-stained gels of the whole protein extracts from the rat aortic smooth and skeletal muscle strips. Results: The expression of PDGF, AngII, TNF$\alpha$, and $H_2O_2$-induced activation of HSP27, p38MAPK, ERK1/2, and SAPK/JNK was higher in the smooth muscle cells than the control. SB203580 (30${\mu}$M), a p38MAPK inhibitor, increased the level of HSP27 phosphorylation induced by stimulators in smooth muscle cells. Furthermore, the age-related and starvation-induced activation of HSP27 was higher in skeletal muscle cells (L6 myoblast cell lines) and muscle strips than the control. Conclusion: These results suggest, in part, that the activity of HSP27 and MAPKs affect stressors, such as PDGF, AngII, TNF$\alpha$, $H_2O_2$, and starvation in rat smooth and skeletal muscles. However, more systemic research will be needed into physical therapy, including thermotherapy, electrotherapy, radiotherapy and others.

• Asian-Australasian Journal of Animal Sciences
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• 제24권5호
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• pp.685-695
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• 2011

Satellite cells are skeletal muscle progenitor/stem cells that reside between the basal lamina and plasma membranes of skeletal fibers in vivo. These cells can give rise to both myogenic and adipogenic cells. Given the possible role for differentiation of satellite cells into adipocytes in marbling and in some pathological disorders like sarcopenia, knowledge of the proteins involved in such process remains obscure. Using two-dimensional polyacrylamide gel electrophoresis coupled with mass spectrometry, we investigated the proteins that are differentially expressed during adipogenic differentiation of satellite cells from bovine longissimus muscle. Our proteome mapping strategy to identify the differentially expressed intracellular proteins during adipogenic differentiation revealed a total of 25 different proteins. The proteins up-regulated during adipogenic differentiation of satellite cells like Cathepsin H precursor, Retinal dehydrogenase 1, Enoyl-CoA hydratase, Ubiquinol-cytochrome-c reductase, T-complex protein 1 subunit beta and ATP synthase D chain were found to be associated with lipid metabolism. The down-regulated proteins like LIM protein, annexin proteins, cofilin-1, Rho GDP-dissociation inhibitor 1 and septin-2, identified in the present study were found to be associated with myogenesis. These results clearly demonstrate that the adipogenic conversion of muscle satellite cells is associated with the up-regulated and down-regulated proteins involved in adipogenesis and myogenesis respectively.

• 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.

• Molecules and Cells
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• 제25권1호
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• pp.78-85
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• 2008

In a search for new molecular pathways associated with asthma, we performed an mRNA differential display analysis using total RNA extracted from the tracheal tissues of ovalbumin (OVA)-challenged mice and sham controls. cDNAs corresponding to mRNAs for which expression levels were altered by OVA-challenge were isolate and sequenced. Twenty-eight genes differentially expressed in sham and OVA challenged mice were identified. A GenBank BLAST homology search revealed that they were related to cytoskeleton remodeling, transcription, protein synthesis and modification, energy production, and cell growth and differentiation. Two were selected for further characterization. Up-regulation of both the perinatal skeletal myosin heavy chain (skMHC) and fast skeletal muscle myosin light chain (skMLC) genes was confirmed by RT-PCR of trachea tissue from OVA challenged mice. Overexpression of skMLC protein was observed in the smooth muscle layers of OVA-challenged mice by immunohistochemistry, and the surface areas stained with skMLC antibody increased in the OVA-challenged mice. The overexpression of skMLC in murine asthma may be associated with the changes of bronchial smooth muscle.

• The Korean Journal of Physiology and Pharmacology
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• 제18권3호
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• pp.255-261
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• 2014

Essential fatty acid (EFA) is known to be required for the body to function normally and healthily. However, the effect of EFA on glucose uptake in skeletal muscle has not yet been fully investigated. In this study, we examined the effect of two EFAs, linoleic acid (LA) and ${\alpha}$-linolenic acid (ALA), on glucose uptake of C2C12 skeletal muscle cells and investigated the mechanism underlying the stimulatory effect of polyunsaturated EFAs in comparison with monounsaturated oleic acid (OA). In palmitic acid (PA)-induced insulin resistant cells, the co-treatment of EFAs and OA with PA almost restored the PA-induced decrease in the basal and insulin-stimulated 2-NBDG (fluorescent D-glucose analogue) uptake, respectively. Two EFAs and OA significantly protected PA-induced suppression of insulin signaling, respectively, which was confirmed by the increased levels of Akt phosphorylation and serine/threonine kinases ($PKC{\theta}$ and JNK) dephosphorylation in the western blot analysis. In PA-untreated, control cells, the treatment of $500{\mu}M$ EFA significantly stimulated 2-NBDG uptake, whereas OA did not. Phosphorylation of AMP-activated protein kinase (AMPK) and one of its downstream molecules, acetyl-CoA carboxylase (ACC) was markedly induced by EFA, but not OA. In addition, EFA-stimulated 2-NBDG uptake was significantly inhibited by the pre-treatment of a specific AMPK inhibitor, adenine 9-${\beta}$-D-arabinofuranoside (araA). These data suggest that the restoration of suppressed insulin signaling at PA-induced insulin resistant condition and AMPK activation are involved at least in the stimulatory effect of EFA on glucose uptake in C2C12 skeletal muscle cells.

• The Korean Journal of Physiology
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• 제17권2호
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• pp.119-124
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• 1983

The in vivo and in vitro buffer capacities of true plasma and tissue buffer capaciies were compared on dogs. Intracellular pH was determined on skeletal muscle by a modification of the method of Schloerb and Grantham using $C^{14}$ DMO. The in vivo curve for plasma or extracellular fluid has a much lower slope than the in vitro curve. The in vivo slope of skeletal muscle in the dog is approximately 20 sl. The slope for skeletal muscle in vivo falls between the in vitro and in vivo slopes of true plasma. It appears that intracellular hydrogen ion varies linearly with extracellular hydrogen ion when $CO_2$ tension is changed. Both hydrogen ion gradient and Hi/He ratio vary in skeletal muscle, with an increase in $CO_2$ tension. Infusion of 0.3N HCl gave two distinct patterns, the $H_i-H_e$ gradient decreased; and it would appear that very little hydrogen ion as such penetrated to the inside of the cells during the time of observation. Although lactic acid presumably enters the cell and the same of larger load was given as was used for hydrochloric acid, only very mild intracellular acidosis resulted, ostensibly due to metabolism of this substrate. Gluconic acid produced a more severe acidosis, both intracellularly and extracellularly, but with both of these acids the hydrogen ion gradient decreased and the $H_i/H_e$ ratio also decreased. The experiments on the dogs with hemorrhagic shock the hydrogen ion increase producing the acidosis originates inside the cells. Even so, the hydrogen ion gradient increased only very slightly in the acute experiments. This may suggest that even over short intervals of time skeletal muscle cells have a capacity to pump out hydrogen ions at a rate which maintains approximately the normal $H_i/H_e$ gradient when the source of the hydrogen ion is in the interior of the cell.

• 대한본초학회지
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• 제31권1호
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• pp.1-5
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• 2016

Objectives : The purpose of this study was to investigate inhibitory effects of steamed Polygonatum odoratum extract (POE) on insulin resistance in rat skeletal muscle cells, L6 cells.Methods : Polygonatum odoratum (P. odoratum) extract was extracted with ethyl acetate. Activity of α-glucosidase in POE was measured for blood glucose regulation. MTT assay was examined for cell toxicity. Western blot analysis for measurement of adiponectine, peroxisome proliferator-activated receptorγ (PPARγ), insulin receptor substrate (IRS), glucose transporter 4 (Glut-4) and phosphorylation of serine/threonine-specific protein kinase (Akt) expressions were performed. Akt signaling pathway were analyzed with LY294002, which is a specific PI3K/Akt inhibitor.Results : The results revealed that POE inhibited α-glucosidase activity. Treatment of POE in L6 cells inhibited the differentiation of L6 cells compared to those of vehicl control. Additionally, protein expressions of adiponectine, PPARγ, IRS and Glut-4 were significantly regulated compared to those of vehicle control (p < 0.05), respectively. Futhermore, phosphorylation of Akt was increased in L6 cells treated with POE compared to that of vehicle control (p < 0.05). pAkt expression was significantly accentuated with Akt inhibitor (LY294002).Conclusions : These results suggest that POE may have potential as a natural agent for prevention/improvement of diabetes, especially, regulation of blood glucose. Therefore, further additional study should be conducted to elucidate in depth the pharmaceutical efficacy of these.

• Animal cells and systems
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• 제1권2호
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• pp.329-335
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• 1997

The final pattern of the skeletal muscle of a vertebrate depends on the position-specific behavior of the muscle precursor cells during early developmental process and the abdominal muscle is made of cells which migrate a relatively long distance from their original tissue, myotome of dorsal mesoderm. We report the spatia-temporal migration pattern of abdominal muscle in Xenopus laevis by in situ hybridization and immunohistological studies. Shortly after hatching tadpole stage (stage 31/32), a group of myotomal cells detaches from the lower tip of the second somite and migrates ventrally to the lower position of abdomen. At stage 34/35, a second cell group migrates away from the third somite. Total 7 myotomal cell groups migrate ventrally one by one from the second to eighth myotome along their own pathways through the cell free space located between epidermis and subepidermal layer of the abdomen. During migration, the sizes of the cell groups (abdominal muscle anlagens) are increased to several tens fold. Around stage 40 all the abdominal muscle anlagens reaches their final positions and are interconnected side by side rostrocaudally. They are also connected to other types of muscles, forming a large multisegmented abdominal muscle. Heat shock study suggests that the disruption of segmentation of somites does not block the detachment of abdominal muscle anlagen, though the treatment gave stage- and dosagedependent effects on the migration speed.

• Journal of Applied Biological Chemistry
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• 제60권4호
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• pp.373-381
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• 2017

Hippocampus abdominalis, the big belly sea horse, is widely known for its medicinal value in Chinese folk medicine. In this study, extract obtained by proteolytic degradation of this species was investigated for its effects on skeletal muscle development, both in vitro and in vivo. Muscle cell lines ($C_2C_{12}$ and $L_6$) treated with the bioactive peptide did not have any detrimental effects on the cell viability, which was above 80%. Optical microscopy analysis on the morphology of the sea horse extract (SHE)-treated cells showed enhanced differentiating ability with myotube formation. Moreover, cells incubated with the hydrolysate displayed decreased proliferation rate, as recorded by the electric cell substrate impedance sensing system, thereby supporting enhanced differentiation. For a period of 12 weeks, mice models were fed with SHE and simultaneously subjected to treadmill exercise, which increased the expression of Myogenin, a key myogenic regulatory factor. In addition, there was an increase in the expression of AMPK- and Cytochrome C, both of which are important in mitochondrial biogenesis. Thus, the SHE from Hippocampus abdominalis can be a promising candidate as protein supplement aiding muscle development.

• Journal of Ginseng Research
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• 제46권3호
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• pp.444-453
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• 2022

Background: Compound K (CK) is among the protopanaxadiol (PPD)-type ginsenoside group, which produces multiple pharmacological effects. Herein, we examined the effects of CK on muscle atrophy under hyperlipidemic conditions along with its pro-myogenic effects. Further, the molecular pathways underlying the effects of CK on skeletal muscle have been justified. Methods: C2C12 myotubes were treated with palmitate and CK. C2C12 myoblasts were differentiated using CK for 4-5 days. For the in vivo experiments, CK was administered to mice fed on a high-fat diet for 8 weeks. The protein expression levels were analyzed using western blotting analysis. Target protein suppression was performed using small interfering (si) RNA transfection. Histological examination was performed using Jenner-Giemsa and H&E staining techniques. Results: CK treatment attenuated ER stress markers, such as eIF2a phosphorylation and CHOP expression and impaired myotube formation in palmitate-treated C2C12 myotubes and skeletal muscle of mice fed on HFD. CK treatment augmented AMPK along with autophagy markers in skeletal muscle cells in vitro and in vivo experiments. AMPK siRNA or 3-MA, an autophagy inhibitor, abrogated the impacts of CK in C2C12 myotubes. CK treatment augmented p38 and Akt phosphorylation, leading to an enhancement of C2C12 myogenesis. However, AMPK siRNA abolished the effects of CK in C2C12 myoblasts. Conclusion: These findings denote that CK prevents lipid-induced skeletal muscle apoptosis via AMPK/autophagy-mediated attenuation of ER stress and induction of myoblast differentiation. Therefore, we may suggest the use of CK as a potential therapeutic approach for treating muscle-wasting conditions associated with obesity.