OBJECTIVETo investigate the effects of time varied stress on the proliferation of myoblast in rats and provide the basic experimental data for the remodeling of tissue in functional orthopaedics.

METHODSBased on the pulsatile mechanical system founded, this study loaded different strain (2.5, 5.0, 10.0 kPa) to the myoblast of lateral pterygoid muscle. The proliferation of myoblast was detected by 3H-TDR.

RESULTSAfter 6 hours under time varied strain, the significant proliferation of myoblast (P < 0.05) was observed, and the 5.0 kPa group expressed the best proliferation. After 12 hours under time varied strain, all groups expressed a better proliferation. Meanwhile, the lower frequency (0.40 Hz) had the bigger effect on the proliferation more than in the higher frequency (1.25 Hz) under the same time varied strain.

CONCLUSIONThe frequency of time varied strain had also the important influence on the proliferation, the lower frequency (0.40 Hz) had the bigger effect on the proliferation more than in the higher frequency (1.25 Hz) under the same time varied strain. In the certain period of time and certain magnitude of time varied strain, the proliferation of myoblasts rised.

Animals ; Myoblasts ; Orthopedics ; Rats ; Time

OBJECTIVETo investigate the effects of time varied stress on the shape-alteration of myoblast in rats and to provide a theoretic base to determine the mechanics of myoblast in orthodontic therapy.

METHODSBased on the pulsatile mechanical system our group founded, this study loaded different strain (2.5 kPa, 5.0 kPa and 10.0 kPa) to the myoblast of lateral pterygoid muscle. The alterations in shape under time varied stress of 6 h and 12 h were assessed by phase-contrast microscopy, scanning electron microscope.

RESULTSThe orientation of myoblast seemed no obvious orderliness before loading. But after loading the lower time varied strain (2.5 kPa, 5.0 kPa), they were changed their orientation to paralel with the direction of strain along with the membrane. Meanwhile, there had one trend to set the shape of myoblast more upright along with the membrane after loading the higher time varied stress (10.0 kPa).

CONCLUSIONIt was proved that the different time varied stress in vitro expressed the different influence on the remolding of myoblast.

Animals ; Myoblasts ; Rats ; Stress, Mechanical

BACKGROUND: A critical shortage of donor organs has necessitated an investigation of new strategies to increase the availability of additional organs available for human transplantation. We investigated the amount of apoptosis and expression of GADD45beta in two groups, a GADD45beta-transfected group and untransfected group. MATERIAL AND METHOD: The experimental groups consist of a control group (normal H9C2 cell line) and GADD45beta-transfected group. After injury of the each group, we evaluated the expression of GADD45beta and the level of apoptosis in each group. RESULT: There was a significant increase in the expression of GADD45beta in the GADD45beta-transfected group at 1 hour, 2 hours, and 3 hours after stimuli as compared with the control group. The amount of cardiac myoblast cell line apoptosis was significantly lower in the GADD45beta-transfected group as compared with the control group. The concentration of annexin in the GADD45beta-transfected group was significantly lower than that of the control group after cell injury. CONCLUSION: Transfection of a rat myoblast cell line with the GADD45beta gene results in decreased susceptibility to cell injury of human serum.
Animals ; Apoptosis ; Cell Line ; Humans ; Myoblasts ; Myoblasts, Cardiac ; Rats ; Tissue Donors ; Transfection ; Transplantation, Heterologous ; Transplants

Granular cell tumors were originally described in 1926 by Abrikossoff as myoblastic myomas. They usually occur as solitary tumors but can be multiple in about 10% of cases. They have a predilection for the skin, subcutaneous tissue and tongue, but also occur in many other organs. We report a case of solitary granular cell tumor on the palm. This is a very unusual location of this disease which merits consideration.
Granular Cell Tumor* ; Myoblasts ; Myoma ; Skin ; Subcutaneous Tissue ; Tongue

BACKGROUND: Muscle is a target of immunological injury in several muscle diseases, such as idiopathic inflammatory myopathy. However, it is also a target for gene therapy. Therefore, it is important to understand the immunological capabilities of muscle cells. To assess as to whether muscle cells are actively involved in the inflamed muscle tissue, a human skeletal muscle cell line was tested for the expression of several cytokines and chemokine at the mRNA level. METHODS: A human skeletal muscle cell line (SKM14) had been developed by a retroviral vector encoding v-myc transfection into a 12-week-old human fetal skeletal muscle tissue characterized by the immunostaining of several musclespecific markers. Human skeletal myoblasts of this cell line were tested for their capacity to express different cytokines (IL-1beta, -6, -10, -12, -15, and TNF-alpha) and chemokine (IL-8) mRNA levels at the basal state and in the presence of TNF-alpha(10 ng/ml). RESULTS: The SKM14 cell line was confirmed to be able to express various cytokines constitutively (IL-6, -8, -12, -15, and TNF-alpha) and in the presence of TNF-alpha(IL-1beta, -6, -8, -10, -12, -15, and TNF-alpha). CONCLUSIONS: Our results suggest that muscle cells may play a role as immunocompetent cells.
Cell Line* ; Cytokines* ; Genetic Therapy ; Humans* ; Muscle Cells ; Muscle, Skeletal* ; Myoblasts ; Myoblasts, Skeletal ; Myositis ; RNA, Messenger* ; Transfection ; Zidovudine

OBJECTIVE: Caveolae are the microdomain of the plasma membrane that have been implicated in signal transduction and caveolin is a principal component of the caveolae. Caveolin-3, a family of caveolin related protein, is expressed only in muscle tissue. Here we examined the expression of caveolin-3 in the course of myobalst differentiation and within the muscle tissue. METHOD: L6 cell, rat skeletal myoblast, was cultured in the low mitogen medium and caveolin-3 expression was observed both by immunocytochemistry and western blot analysis. Localization of caveolin-3 within the muscle tissue was investigated and compared to that of dystrophin. RESULTS: While caveolin-3 was not expressed in the proliferating myolast, caveolin-3 was expressed in the differentiated myoblast. Caveolin-3 and dystrophin were co-expressed in the membrane of muscle tissue and integrated density of caveolin-3 was elevated in the area of muscle injury. In the Duchenne muscular dystrophy, caveolin-3 was expressed in the membrane of muscle tissue, but dystrophin was not. CONCLUSION: Caveolin-3 was induced during the myobalst differentiation and its expression was increased during the muscle regeneration. Caveolin-3 was physically associated with dystrophin as a complex, but not absolutely required for the biogenesis of dystrophin complex.
Animals ; Organelle Biogenesis ; Blotting, Western ; Caveolae ; Caveolin 3* ; Cell Membrane ; Dystrophin ; Humans ; Immunohistochemistry ; Membranes ; Muscle Cells* ; Muscle, Skeletal ; Muscular Dystrophy, Duchenne ; Myoblasts ; Myoblasts, Skeletal ; Rats ; Regeneration ; Signal Transduction

Sumoylation, the conjugation of a small ubiquitin-like modifier (SUMO) protein to a target, has diverse cellular effects. However, the functional roles of the SUMO modification during myogenesis have not been fully elucidated. Here, we report that basal sumoylation of histone deacetylase 1 (HDAC1) enhances the deacetylation of MyoD in undifferentiated myoblasts, whereas further sumoylation of HDAC1 contributes to switching its binding partners from MyoD to Rb to induce myocyte differentiation. Differentiation in C2C12 skeletal myoblasts induced new immunoblot bands above HDAC1 that were gradually enhanced during differentiation. Using SUMO inhibitors and sumoylation assays, we showed that the upper band was caused by sumoylation of HDAC1 during differentiation. Basal deacetylase activity was not altered in the SUMO modification-resistant mutant HDAC1 K444/476R (HDAC1 2R). Either differentiation or transfection of SUMO1 increased HDAC1 activity that was attenuated in HDAC1 2R. Furthermore, HDAC1 2R failed to deacetylate MyoD. Binding of HDAC1 to MyoD was attenuated by K444/476R. Binding of HDAC1 to MyoD was gradually reduced after 2 days of differentiation. Transfection of SUMO1 induced dissociation of HDAC1 from MyoD but potentiated its binding to Rb. SUMO1 transfection further attenuated HDAC1-induced inhibition of muscle creatine kinase luciferase activity that was reversed in HDAC1 2R. HDAC1 2R failed to inhibit myogenesis and muscle gene expression. In conclusion, HDAC1 sumoylation plays a dual role in MyoD signaling: enhancement of HDAC1 deacetylation of MyoD in the basally sumoylated state of undifferentiated myoblasts and dissociation of HDAC1 from MyoD during myogenesis.
Creatine Kinase, MM Form ; Gene Expression ; Histone Deacetylase 1 ; Histone Deacetylases ; Histones ; Luciferases ; Muscle Cells ; Muscle Development ; Myoblasts ; Myoblasts, Skeletal ; Sumoylation ; Transfection

Animals ; Cell Differentiation ; physiology ; Cell Hypoxia ; Cell Line ; Mice ; Myoblasts ; cytology ; Transcription Factors ; metabolism

OBJECTIVETo observe the effects of 17beta-estradiol on the intracellular calcium of masticatory muscles myoblast.

METHODSMyoblasts from maxillofacial skeletal muscle of one week old female Sprague-Dawley rats were cultured. Fluo-4-AM as the Ca2+ indicator and the laser confocal microscope system were used to observe the effects of estrogen on the cytoplasmic Ca2+ concentration in the normal pH condition and the acid condition (pH = 6.7).

RESULTSIn the normal pH condition, when 17beta-estradiol (10(-9), 10(-8), 10(-7) mol/L) were added to cells cytoplasmic Ca2+ immediately increased then decreased right away, and in the end came into a new Ca2+ homeostasis in the base line. In the acid condition, 17beta-estradiol (10(-9), 10(-8), 10(-7) mol/L) made the cytoplasmic Ca2+ decreased immediately then came into a new Ca2+ homeostasis under the base line.

CONCLUSIONThe results suggest that estrogen may maintain the skeletal cytoplasmic Ca2+ concentration in a lower level and reduce the cytoplasmic Ca2+ accumulation to keep the normal functions of masticatory muscles myoblast.

Aniline Compounds ; Animals ; Calcium ; Estradiol ; Female ; In Vitro Techniques ; Masticatory Muscles ; Myoblasts ; Rats ; Rats, Sprague-Dawley ; Xanthenes

OBJECTIVETo investigate the effect of cyclic stretch on p38 mitogen-activated protein kinase (p38MAPK) signaling pathway during stretch-induced differentiation process of C2C12 myoblasts.

METHODSC2C12 cells were seeded on Bio Flex 6-well plates, and cells were subsequently subjected to cyclic stretch at an optimal magnitude (10%) and frequency (0.5 Hz). The effects of cyclic stretch were examined at 2, 6, 12, 24 h. Antibodies specific to p38MAPK phosphorylated forms and the total protein levels of the p38MAPK were examined using Western blot analysis.

RESULTSThese results indicated that p38MAPK was activated during stretch-induced C2C12 cell differentiation. The level of phosphorylated protein was higher in the p38MAPK signaling pathway. The expression of total protein was maintained at baseline level. There were no significant differences between groups. Treatment of cells with specific p38MAPK inhibitor SB203580 could decrease the expression of myogenin, but not completely abolish the myogenin expression after stretch.

CONCLUSIONp38MAPK signaling pathway plays an important role during stretch-induced differentiation process of C2C12 myoblasts, but is not activated exclusively in this process.

Cell Differentiation ; Humans ; Imidazoles ; Myoblasts ; Phosphorylation ; Pyridines ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases