• 생명과학회지
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• 제26권7호
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• pp.758-763
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• 2016

본 연구에서는 C2C12 근육 세포의 분화 과정에 있어 IGF-I이 지방산의 수송을 담당하는 지방산 수송체인 FAT/CD36의 mRNA 및 단백질 발현에 미치는 영향에 대해 알아보았다. 그 결과 근육세포의 분화 과정에 있어 FAT/CD36의 단백질과 mRNA 발현이 분화 시간 의존적으로 유의하게 증가하였으며, IGF-I의 처리에 의해서도 유의하게 조절되었음을 알 수 있었다. 이는 IGF-I이 골격근 세포의 성장 및 분화를 촉진하여 근육 관련 유전자들의 발현을 조절하는 기능뿐만 아니라, 골격근의 주요 에너지원으로 사용되는 지방산의 수송을 담당하는 FAT/CD36의 발현에도 영향을 미친다는 것으로 해석할 수 있겠다. 향후 IGF-I이 골격근 세포에서 FAT/CD36의 발현에 영향을 미침으로써 골격근의 지방산 흡수와 산화율을 조절하는지, 그에 따라 지방대사에 어떠한 영향을 미치는지에 대한 연구가 필요할 것이며, 이와 관련된 신호전달 체계 및 기전에 대한 연구도 진행 되어야 할 것이다.

• Molecules and Cells
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• 제28권3호
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• pp.189-194
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• 2009

The modulating effect of IGF-I on the regulation of AR gene expression and activation in skeletal muscle cells remains poorly understood. In this study, the effects of IGF-I treatment on AR induction and activation in the absence of AR ligands were examined. Differentiating C2C12 cells were treated with different concentrations (0-250 ng/ml) of IGF-I or for various periods of time (0-60 min) of 250 ng/ml IGF-I. Treatment of C2C12 cells with IGF-I resulted in a dose- and time-dependent increase in total AR and phosphorylated AR (Ser 213). IGF-I treatment also led to significantly increased AR mRNA expression when compared with the control. The levels of skeletal ${\alpha}-actin$ and myogenin mRNA, known target genes of AR, were also significantly upregulated after 5 or 10 min of treatment with IGF-I. Confocal images revealed that IGF-I stimulated nuclear localization of AR in the absence of ligands. In addition, an electrophoretic mobility shift assay indicated that IGF-I stimulated the AR DNA binding activity in a time-dependent manner. The present results suggest that IGF-I stimulates the expression and activation of AR by ligand-independent mechanism in differentiating C2C12 mouse skeletal muscle cells.

• 대한의생명과학회지
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• 제6권3호
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• pp.171-179
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• 2000

대부분 척추동물에서 골격근 내 filament들의 길이 조절은 근 수축 기작의 구조를 이해하는데 중요한 단서가 된다. Nebulin은 thin filament의 전체에 걸쳐있는 거대한 단백질로 골격근에만 특이적으로 존재하는 것으로 알려져 왔다. 본 연구에서는 닭의 근육과 비근육 조직에서 nebulin isoform단백질들을 확인하기 위하여 전기영동과 immunoblot의 방법을 이용하였다. 각 조직의 단백질들은 soluble과 insoluble fraction으로 분리 준비하였다. 실험결과, 닭의 근육과 비근육 조직들에서 조직 특이성을 나타내는 다양한 nebulin isoform 단백질들이 확인되었다. Nebulin은 성계의 골격근에서 500 kDa 정도의 크기로 나타났고, nebulett은 계배와 성계의 심장근에서 107 kDa 정도로 발현되었다. 그리고 계배의 비근육 조직인 뇌에서 380 kDa 정도의 거대 단백질이 확인되었다. 이 단백질은 뇌 조직의 soluble fraction에서 인지되었다. Nebulin isoform 단백질들이 서로 다른 조직에서 발현되는 양상을 보아 서로 다른 독자적인 기능을 가질 것으로 추정된다.

• Journal of Ginseng Research
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• 제43권3호
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• pp.475-481
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• 2019

Background: The ginsenoside Rg1 has been shown to exert various pharmacological activities with health benefits. Previously, we have reported that Rg1 promoted myogenic differentiation and myotube growth in C2C12 myoblasts. In this study, the in vivo effect of Rg1 on fiber-type composition and oxidative metabolism in skeletal muscle was examined. Methods: To examine the effect of Rg1 on skeletal muscle, 3-month-old mice were treated with Rg1 for 5 weeks. To assess muscle strength, grip strength tests were performed, and the lower hind limb muscles were harvested, followed by various detailed analysis, such as histological staining, immunoblotting, immunostaining, and real-time quantitative reverse transcription polymerase chain reaction. In addition, to verify the in vivo data, primary myoblasts isolated from mice were treated with Rg1, and the Rg1 effect on myotube growth was examined by immunoblotting and immunostaining analysis. Results: Rg1 treatment increased the expression of myosin heavy chain isoforms characteristic for both oxidative and glycolytic muscle fibers; increased myofiber sizes were accompanied by enhanced muscle strength. Rg1 treatment also enhanced oxidative muscle metabolism with elevated oxidative phosphorylation proteins. Furthermore, Rg1-treated muscles exhibited increased levels of anabolic S6 kinase signaling. Conclusion: Rg1 improves muscle functionality via enhancing muscle gene expression and oxidative muscle metabolism in mice.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.43-48
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• 2002

We show that humans execute the postural control ingeniously by regulating the impedance properties of the musculo-skeletal system as the motor command against the alteration of the environment. Adjusting muscle activity can control the impedance properties of the musculo-skeletal system. To quantify the changes in human arm viscoelasticity on the vertical plane during interaction with the environment, we asked our subject to hold an object. By utilizing surface electromyographic(EMG) studies, we determined a relationship between the perturbation and a time-varying muscle co-activation. Our study showed when the subject lifts the object by himself the muscle stiffness increases while the torque remains the same just before the lift-off. These results suggest that the central nervous system(CNS) simultaneously controls not only the equilibrium point(EP) and the torque, but also the muscle stiffness as themotor command in posture control during the contact task.

• Asian-Australasian Journal of Animal Sciences
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• 제21권3호
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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.

• Animal Bioscience
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• 제36권12호
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• pp.1775-1784
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• 2023

Objective: The aim of this study was to reveal the role and regulatory mechanism of miR-188-5p in the proliferation and differentiation of goat muscle satellite cells. Methods: Goat skeletal muscle satellite cells isolated in the pre-laboratory were used as the test material. First, the expression of miR-188-5p in goat muscle tissues at different developmental stages was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, miR-188-5p was transfected into goat skeletal muscle satellite cells by constructing mimics and inhibitors of miR-188-5p, respectively. The changes of differentiation marker gene expression were detected by qPCR method. Results: It was highly expressed in adult goat latissimus dorsi and leg muscles, goat fetal skeletal muscle, and at the differentiation stage of muscle satellite cells. Overexpression and interference of miR-188-5p showed that miR-188-5p inhibited the proliferation and promoted the differentiation of goat muscle satellite cells. Target gene prediction and dual luciferase assays showed that miR-188-5p could target the 3'untranslated region of the calcium/calmodulin dependent protein kinase II beta (CAMK2B) gene and inhibit luciferase activity. Further functional studies revealed that CAMK2B promoted the proliferation and inhibited the differentiation of goat muscle satellite cells, whereas si-CAMK2B restored the function of miR-188-5p inhibitor. Conclusion: These results suggest that miR-188-5p inhibits the proliferation and promotes the differentiation of goat muscle satellite cells by targeting CAMK2B. This study will provide a theoretical reference for future studies on the molecular mechanisms of skeletal muscle development in goats.

• 대한의생명과학회지
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• 제10권1호
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• pp.23-29
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• 2004

Nebulin is a (Mr 600∼900 kDa) large actin-binding protein specific to skeletal muscle and thought to act as a molecular template that regulates the length of thin filaments. Cardiac muscles of higher vertebrates have been shown earlier to lack nebulin. Recently, full-length nebulin mRNA transcripts have been detected in heart muscle, but at lower levels than in skeletal muscle. Nebulin expression also was detected in the kidney, eye, and otic canal, suggesting that nebulin isoforms may also be expressed in these organs. We have searched for nebulin isoforms in brain of human using PCR and Northern blot. Here, we provide evidence that nebulin mRNA transcripts are expressed in brain. Seven nebulin isoforms (B, C, D, E, F, G and H form) are obtained in human skeletal muscle and four isoforms (B, C, G and H form) in human brain cDNA library. We cloned the 1.3 kb of nebulin fragment from human adult brain library by PCR. The identity of the PCR product was confirmed by sequence analysis. The partial brain nebulin sequence was 99% identical to the skeletal muscle cDNA as determined by Blast alignment. It contains two simple-repeats HR1, HR2 and linker-repeats exon l35∼143 except exon 140. It was different from skeletal muscle B form, which contain HR1 and HR8. These data suggest that nebulin isoform diversity occurs even more extensively than previously known, likely contributing to the distinct thin filament architecture of different striated muscles.

• The Journal of Korean Physical Therapy
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• 제19권4호
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• pp.1-14
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• 2007

Background: It is generally accepted that skeletal muscle contraction is triggered by nerve impulse and intracellular $Ca^{2+}\;([Ca^{2+}]_i)$ released from intracellular $Ca^{2+}$ stores such as sarcoplasmic reticulum (SR). Specifically, this process, called excitation-contraction (E-C) coupling, takes place at intracellular junctions between the plasma membrane, the transverse (T) tubule L-type $Ca^{2+}$ channel (dihydropyridine-sensitive L-rype $Ca^{2+}$ channel, DHPR, also called tetrads), and the SR $Ca^{2+}$ release channel (ryanodine-sensitive $Ca^{2+}$ release channel, RyR, also called feet) of internal $Ca^{2+}$ stores in skeletal muscle cells. Furthermore, it has been reported that the $Ca^{2+-}$ dependent and -independent contraction determine the expression of skeletal muscle genes, thus providing a mechanism for tightly coupling the extent of muscle contraction to regulation of muscle plasticity-related excitation-transcription (E-T) coupling. Purpose: Expression and activity of plasticity-associated enzymes in gastrocnemius muscle strips have not been well studied, however. Methods: Therefore, in this study the expression and phosphorylation of E-C and E-T coupling-related mediators such as protein kinases, ROS(reactive oxygen species)- and apoptosis-related substances, and others in gastrocnemius muscles from rats was examined. Results: I found that expression and activity of MAPKs (mitogen-activated protein kinases, ERK1/2, p38MAPK, and SAPK/JNK), apoptotic proteins (cleaved caspase-3, cytochrome c, Ref-1, Bad), small GTP-binding proteins (RhoA and Cdc42), actin-binding protein (cofilin), PKC (protein kinase C) and $Ca^{2+}$ channel (transient receptor potential channel 6, TRPC6) was observed in rat gastrocnemius muscle strips. Conclusion: These results suggest that MAPKs, ROS- and apoptosis-related enzymes, cytoskeleton-regulated proteins, and $Ca^{2+}$ channel may in part functionally import in E-C and E-T coupling from rat skeletal muscles.

• The Journal of Korean Physical Therapy
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• 제14권3호
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• pp.373-406
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• 2002

This study was peformed to investigate the effects on skeletal muscle recovery with aqua-exercise; swimming to take the muscle endurance for 20 days on two group of white rats which were the low extremity atrophy group(control groups) by fixed for two weeks and aqua-exercise group(experimental groups) after it. The effects was observed with light and electron microcope to measure the morphological changes of muscle fibers. The results obtained were as follow. 1. Light microscope: In the case of control groups, quadriceps fibers had been irregular alignment, decreased muscle width and the irregular alignment nuclear appeared, as it is degenerative muscle fibers. In the case of experimental groups, the fibers had been regular alignment cells and fibers. The nucleus of muscle had been normal characterized by oval shape and fiber sarcomere clearly classified. 2. Electron microscope: In the case of control groups, there were the quadriceps which was Z-line streaming phenomenon induced at the sarcomere and cells nuclear separated from basal membrane. It was not only observed the sarcomere alignment irregularly and mitochondria damaged, but also vacuoles found. In the case of experimental groups, A band, I band, H band had been clearly appeared, classified at the myofibrils of quadriceps, and electronic dense M-line found in sarcomere. There were observed satellite cells and basal laminas that usually to be appeared at the time of mitochondrial development, skeletal muscle fiber regeneration or development. This results suggest that the aqua-exercise assisted to inhibit the degenerative morphological changes of skeletal muscle cells and help to recover from abnormal states. Especially, it is considered to effect on a normal structural formation.