• BMB Reports
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• v.52 no.1
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• pp.64-69
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• 2019

The loss of skeletal muscle, called sarcopenia, is an inevitable event during the aging process, and significantly impacts quality of life. Autophagy is known to reduce muscle atrophy caused by dysfunctional organelles, even though the molecular mechanism remains unclear. Here, we have discuss the current understanding of exercise-induced autophagy activation in skeletal muscle regeneration and remodeling, leading to sarcopenia intervention. With aging, dysregulation of autophagy flux inhibits lysosomal storage processes involved in muscle biogenesis. AMPK-ULK1 and the $FoxO/PGC-1{\alpha}$ signaling pathways play a critical role in the induction of autophagy machinery in skeletal muscle, thus these pathways could be targets for therapeutics development. Autophagy has been also shown to be a critical regulator of stem cell fate, which determines satellite cell differentiation into muscle fiber, thereby increasing muscle mass. This review aims to provide a comprehensive understanding of the physiological role of autophagy in skeletal muscle aging and sarcopenia.

• Food Science of Animal Resources
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• v.40 no.5
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• pp.852-859
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• 2020

The muscle stem cells of domestic animals are of interest to researchers in the food and biotechnology industries for the production of cultured meat. For producing cultured meat, it is crucial for muscle stem cells to be efficiently isolated and stably maintained in vitro on a large scale. In the present study, we aimed to optimize the method for the enrichment of pig muscle stem cells using a magnetic-activated cell sorting (MACS) system. Pig muscle stem cells were collected from the biceps femoris muscles of 14 d-old pigs of three breeds [Landrace×Yorkshire×Duroc (LYD), Berkshire, and Korean native pigs] and cultured in skeletal muscle growth medium-2 (SkGM-2) supplemented with epidermal growth factor (EGF), dexamethasone, and a p38 inhibitor (SB203580). Approximately 30% of total cultured cells were nonmyogenic cells in the absence of purification in our system, as determined by immunostaining for cluster of differentiation 56 (CD56) and CD29, which are known markers of muscle stem cells. Interestingly, following MACS isolation using the CD29 antibody, the proportion of CD56⁺/CD29⁺ muscle stem cells was significantly increased (91.5±2.40%), and the proportion of CD56 single-positive nonmyogenic cells was dramatically decreased. Furthermore, we verified that this method worked well for purifying muscle stem cells in the three pig breeds. Accordingly, we found that CD29 is a valuable candidate among the various marker genes for the isolation of pig muscle stem cells and developed a simple sorting method based on a single antibody to this protein.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.10
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• pp.1447-1460
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• 2009

Myogenic satellite cells have been isolated and identified by several recently elucidated molecular markers. Furthermore, knowledge about the precise function of these markers has provided insight into the early and terminal events of satellite cells during proliferation, differentiation, transdifferentiation, specification and activation. Recently, quiescent myogenic satellite cells have been associated with possession of Pax 3 and 7 that represent pluripotent stem cells capable of differentiating into other lineages. However, the mechanism by which myogenic satellite cells attain pluripotent potential remain elusive. Later, transdifferentiating ability of these cells to another lineage in the absence or presence of certain growth factor/ or agents has revolutionized the scope of these pluripotent myogenic satellite cells for manipulation of animal production (in terms of quality and quantity of muscle protein) and health (in terms of repair of skeletal muscle, cartilage or bone).

• The korean journal of orthodontics
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• v.42 no.5
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• pp.249-254
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• 2012

Objective: To investigate the stem cell-like characteristics of human periodontal ligament (PDL) stromal cells outgrown from orthodontically extracted premolars and to evaluate the potential for myogenic differentiation. Methods: PDL stromal cells were obtained from extracted premolars by using the outgrowth method. Cell morphological features, self-replication capability, and the presence of cell-surface markers, along with osteogenic, adipogenic, and chondrogenic differentiation, were confirmed. In addition, myogenic differentiation was induced by the use of 5-aza-2'-deoxycytidine (5-Aza) for DNA demethylation. Results: PDL stromal cells showed growth patterns and morphological features similar to those of fibroblasts. In contrast, the proliferation rates of premolar PDL stromal cells were similar to those of bone marrow and adipogenic stem cells. PDL stromal cells expressed surface markers of human mesenchymal stem cells (i.e., CD90 and CD105), but not those of hematopoietic stem cells (i.e., CD31 and CD34). PDL stromal cells were differentiated into osteogenic, adipogenic, and chondrogenic lineages. Myotube structures were induced in PDL stromal cells after 5-Aza pretreatment, but not in the absence of 5-Aza pretreatment. Conclusions: PDL stromal cells isolated from extracted premolars can potentially be a good source of postnatal stem cells for oromaxillofacial regeneration in bone and muscle.

• Journal of Animal Science and Technology
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• v.52 no.4
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• pp.329-336
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• 2010

Myogenic satellite cells (MSCs) are mononuclear, multipotent progenitors of adult skeletal muscle possessing a capacity of forming adipocyte-like cells (ALC). To identify the skeletal muscle type-specific myogenic and adipogenic genes during MSCs differentiation, total RNA was extracted from bovine MSCs, myotube-formed cell (MFC), and ALC from each of Beef shank, Longissimus dorsi, Deep pectoral, and Semitendinosus. DNA microarray analysis (24,000 oligo chip) comparing MSCs with MFC and ALC, respectively, revealed 135 differentially expressed genes (> 4 fold) among four cuts. Real-time PCR confirmed expression of 29 genes. Furthermore, the whole tissue sample RNAs analysis showed 6 differentially expressed genes in Beef shank. Among which, 1 gene in MSCs, 4 in MFC, and 1 in ALCs were highly expressed. This study will provide an insight for better understanding the molecular mechanism of differentiation of skeletal muscle type-specific MSCs. The identified genes may be used as marker to distinguish skeletal muscle types.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.8
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• pp.1171-1177
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• 2015

The objective of this study was to establish the optimum protocol for the isolation and culture of porcine muscle satellite cells. Mononuclear muscle satellite cells are a kind of adult stem cell, which is located between the basal lamina and sarcolemma of muscle fibers and is the primary source of myogenic precursor cells in postnatal muscle. Muscle satellite cells are a useful model to investigate the mechanisms of muscle growth and development. Although the isolation and culture protocols of muscle satellite cells in some species (e.g. mouse) have been established successfully, the culture system for porcine muscle satellite cells is very limited. In this study, we optimized the isolation procedure of porcine muscle satellite cells and elaborated the isolation and culture process in detail. Furthermore, we characterized the porcine muscle satellite cells using the immunofluorecence. Our study provides a reference for the isolation of porcine muscle satellite cells and will be useful for studying the molecular mechanisms in these cells.

• Journal of Animal Science and Technology
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• v.54 no.3
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• pp.219-226
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• 2012

Gender specificity in muscle growth and development is well known. Genesis of muscle is dependent on proliferation and differentiation potential of resident myogenic satellite cells (MSCs) present in muscle fibers. Multipotential capacity of forming myocyte, osteocyte, and adipocyte like cell makes MSCs a unique stem cell. To understand the molecular mechanism involved in determination of muscle quality due to difference in hormone concentration of different gender of animals, MSCs were isolated from bovine skeletal muscle and cultured in male, female, and castrated serum supplemented media. DNA microarray used consisted of 24,000 spots with 70 mer oligo in each spot. A total of 88 genes were up-regulated and 551 genes were down-regulated by more than two fold. Among up-regulated gene, 33, 34, and 21 genes were found up-regulated in cells grown in male, female, and castrated serum, respectively. Interestingly, male serum showed 4, female 11 and castrated male showed 4 genes expressed highly in each gender. Further study on the highly up-regulated gene may unfold the mystery of gender specificity found in muscle development. Also, the identification of differentially expressed genes in gender-specific serum will add information on infrastructure of bovine genome research.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.76-76
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• 2003

Pluripotent embryonic stem cells can differentiate into beating cardiomyocytes with proper culture conditions and stimulants via embryo-like aggregates. We describe here the use of mouse embryonic stem (mES03) cells as a reproducible differentiation system for cardiomyocyte. mES03 cells growing in colonies were dissociated and allowed to re-aggregated in suspension [embryoid body (EB) formation〕. To induce cardiomyocytic differentiation, cells were exposed to 0.75% dimethyl sulfoxide (DMSO) during EB formation for 4 days and then another 4 days without DMSO (4+/4-). Thus treated EB was plated onto gelatin-coated dishes for differentiation. Spontaneously contracting colonies which appeared in approximately 4~5 days upon differentiation were mechanically dissected, enzymatically dispersed, plated onto coverslips, and then incubated for another 48~72 hrs. By RT-PCR, robust expression of cardiac myosin heavy chain $\alpha$, cardiac muscle heavy polypeptide 7 $\beta$($\beta$-MHC), cardiac transcription factor GATA4, and skeletal muscle-specific $\alpha$$_1$-subunit of the L-type calcium channel ($\alpha$$_1$CaC $h_{sm}$ ) were detected as early as 8 days after EB formation, but message of cardiac muscle-specific $\alpha$$_1$-subunit of the L-type calcium channel ($\alpha$$_1$CaCh) were reveled at a low level. In contrast, expression of myosin light chain (MLC-2V) and atrial natriuretic factor (ANF) were not detected during EB formation for 8 days. However, a strong expression of the atrial-specific ANF gene was expressed from day 8 onward, which were remained constant in EB. (cardiac specialization and terminal differentiation stage). Electrophysiological examination of spontaneously contracting cells showed ventricle-like action potential 17 days after the EB formation. This study indicates that mES03 cell-derived cardiomyocytes via 4+/4- protocol displayed biochemical and electrophysiological properties of subpopulation of cardiomyocytes.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.100-100
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• 2003

Pluripotent embryonic stem (ES) cells differentiate spontaneously into beating cardiomyocytes via embryo-like aggregates. We describe the use of mouse embryonic stem (mES03) cells as a reproducible differentiation system for cardiomyocyte. To induce cardiomyocytic differentiation, mES03 cells were dissociated and allowed to aggregate (EB formation) at the presence of 0 75% dimethyl sulfoxide (DMSO) for 4 days and then another 4 days without DMSO (4+/4-). Thus treated EBs were plated onto gelatin-coated dish for differentiation. Spontaneously contracting colonies which appeared in approximately 4-5 days upon differentiation. Expression of cardiac-specific genes were determined by RT-PCR. Rebust expression of myosin light chain (MLC-2V), cardiac myosin heavy chain $\alpha$, cardiac muscle heavy polypeptide 7 $\beta(\beta$-MHC), cardiac transcription factor GATA4 and skeletal muscle-specific ${\alpha}_1$-subunit of the L-type calcium channel (${\alpha}_1 CaCh_{sm}$) were detected as early as 8 days after EB formation, but message of cardiac muscle-specific $\alpha$$_1$-subunit of the L-type calcium channel (${\alpha}_1$CaCh) were revealed at a low level. Strikingly, the expression of atrial natriuretic factor (ANF) was not detected. When spontaneous contracting cell masses were examined their electrophysiological features by patch-clamp technique, it showed ventricle-like action potential 17 days after the EB formation. This study indicates that mES03 cell-derived cardiomyocytes displayed biochemical and electrophysiological properties of cardiomyocytes and DMSO enhanced development of cardiomyocytes in 4+/4- method.

• Korean Journal of Pharmacognosy
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• v.39 no.3
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• pp.228-232
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• 2008

Antidiabetic effects of an aqueous and solvent extract prepared from the root, stem and fruit parts of Acanthopanax senticosus, were investigated in experimental Streptozotocin (STZ)-induced diabetic rats model. The n-butanol and water extracts of A. senticosus were orally administrated once a day for 6 days. The n-butanol extracts of fruit (FB) showed highest efficiency than other groups (water extracts of stem, root and fruit; butanol extracts of stem, root) on serum glucose values in the STZ-induced diabetic rats. We have studied gene expression of glucose transporter genes in C2C12 skeletal muscle cell line during differentiation treated by the n-butanol and water extracts of A. senticosus, SW, RW, FW, SB, RB and FB. The GLUT4 gene was high expressed by FB treatment. These findings suggest that FB of A. senticosus have GLUT4 gene expression activity for glucose homeostasis and may have beneficial effects on blood glucose lowering in the diabetic patients.