Diabetes mellitus is a complex metabolic disorder characterized by chronic hyperglycemia due to absolute or relative lack of insulin. Though great efforts have been made to investigate the pathogenesis of diabetes, the underlying mechanism behind the development of diabetes and its complications remains unexplored. Cumulative evidence has linked mitochondrial modification to the pathogenesis of diabetes and its complications and they are also observed in various tissues affected by diabetes. Proteomics is an attractive tool for the study of diabetes since it allows researchers to compare normal and diabetic samples by identifying and quantifying the differentially expressed proteins in tissues, cells or organelles. Great progress has already been made in mitochondrial proteomics to elucidate the role of mitochondria in the pathogenesis of diabetes and its complications. Further studies on the changes of mitochondrial protein specifically post-translational modifications during the diabetic state using proteomic tools, would provide more information to better understand diabetes.
Adipose Tissue ; metabolism ; Diabetes Complications ; Diabetes Mellitus ; metabolism ; pathology ; Humans ; Insulin ; metabolism ; Insulin-Secreting Cells ; cytology ; metabolism ; Liver ; metabolism ; Mitochondria ; metabolism ; Muscle, Skeletal ; metabolism ; Proteome ; metabolism ; Proteomics

Myostatin, a member of the TGF-beta family, negatively regulates skeletal muscle development. Mutation of myostatin activity leads to increases muscle growth and carcass lean yield. The bovine myostatin mutation cDNA was amplified by polymerase chain reaction, and then sub-cloned into the expression vector pET-30a( + ) to form the expression plasmid pET30a (+)-action/ Myostatin. The recombinant plasmid was transformed into E. coli BL21. The overexpression product of pET30a (+)-action/ Myostatin was been showed in vitro. Sheep skeletal muscle cell were cultured with the purified myostatin mutation C-terminal peptide. The results of this study suggest that had a powerful activity to stimulate the hyperplasia and proliferation of sheep muscle cells and shows high biochemical activity.
Animals ; Cattle ; Cell Proliferation ; Cells, Cultured ; Cloning, Molecular ; Genetic Vectors ; genetics ; Muscle Development ; genetics ; physiology ; Muscle, Skeletal ; cytology ; metabolism ; Mutation ; Myostatin ; genetics ; metabolism ; Peptides ; genetics ; metabolism ; Sheep

The Forkhead box O1 (FoxO1) transcription factor governs muscle growth, metabolism and cell differentiation. However, its role in myoblast differentiation is unclear. To study the biological function of FoxO1 during differentiation in porcine primary myoblast, we constructed stably FoxO1 over-expressed porcine myoblast mediated by liposome and adopted morphological observation, quantitative real-time RT-PCR and Western blotting methods to analyze FoxO1 and early and late myogenic regulation factors MyoD and myogenin expression. During differentiation the mRNA level of FoxO1 was significantly increased. However, the total protein did not change but the phosphorylation of FoxO1 was upregulated. Furthermore, overexpression of FoxO1 in porcine myoblast decreased MyoD and myogenin mRNA, whereas MyoD protein changed little and myogenin was significantly suppressed (P < 0.05). These results indicated that FoxO1 delays and negatively regulates the porcine myoblast differentiation. Moreover, FoxO1 may play a critical role in muscle fiber-type specification through the inhibition of myogenic regulation factors.
Animals ; Animals, Newborn ; Cell Differentiation ; genetics ; Cells, Cultured ; Forkhead Transcription Factors ; biosynthesis ; genetics ; Muscle, Skeletal ; cytology ; metabolism ; Myoblasts ; cytology ; metabolism ; RNA, Messenger ; biosynthesis ; genetics ; Swine

It is now well established that inflammation plays an important role in the development of numerous chronic metabolic diseases including insulin resistance (IR) and type 2 diabetes (T2DM). Skeletal muscle is responsible for 75% of total insulin-dependent glucose uptake; consequently, skeletal muscle IR is considered to be the primary defect of systemic IR development. Our pre- vious study has shown that rutaecarpine (Rut) can benefit blood lipid profile, mitigate inflammation, and improve kidney, liver, pan- creas pathology status of T2DM rats. However, the effects of Rut on inflammatory cytokines in the development of IR-skeletal muscle cells have not been studied. Thus, our objective was to investigate effects of Rut on inflammatory cytokines interleukiri (IL)-1, IL-6 and tumor necrosis factor (TNF)-α in insulin resistant primary skeletal muscle cells (IR-PSMC). Primary cultures of skeletal muscle cells were prepared from 5 neonate SD rats, and the primary rat skeletal muscle cells were identified by cell morphology, effect of ru- taecarpine on cell proliferation by MTT assay. IR-PSMC cells were induced by palmitic acid (PA), the glucose concentration was measured by glucose oxidase and peroxidase (GOD-POD) method. The effects of Rut on inflammatory cytokines IL-1, IL-6 and TNF-α in IR-PSMC cells were tested by enzyme-linked immunosorbent assay (ELISA) kit. The results show that the primary skeletal muscle cells from neonatal rat cultured for 2-4 days, parallel alignment regularly, and cultured for 7 days, cells fused and myotube formed. It was shown that Rut in concentration 0-180. 0 μmol x L(-1) possessed no cytotoxic effect towards cultured primary skeletal muscle cells. However, after 24 h exposure to 0.6 mmol x L(-1) PA, primary skeletal muscle cells were able to induce a state of insulin resistance. The results obtained indicated significant decrease (P < 0.05 to P < 0.001) IL-1, IL-6 and TNF-α production by cultured IR-PSMC cells when incubating 24 hours with Rut, beginning from 20 to 180.0 μmol x L(-1). IL-1, IL-6 and TNF-α in the Rut treated groups were dose-dependently decreased compared with that in the IR-PSMC control group. Our results demonstrated that the Rut promoted glucose consumption and improved insulin resistance possibly through suppression of inflammatory cytokines in the IR-PSMC cells.
Animals ; Cell Proliferation ; drug effects ; Cytokines ; metabolism ; Female ; Glucose ; metabolism ; Indole Alkaloids ; pharmacology ; Inflammation ; metabolism ; Insulin Resistance ; Male ; Muscle, Skeletal ; cytology ; drug effects ; metabolism ; Quinazolines ; pharmacology ; Rats

OBJECTIVETo investigate the expressions of myogenic markers MyoD, myogenin,and desmin in skeletal muscle differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs).

METHODSMyogenic markers MyoD, myogenin,and desmin of hBM-MSCs cultured in vitro were detected by immunofluorescence and RT-PCR. A total of 21 8-to-10 week-old immunosuppressed mdx mice were transplanted with 1x107 passage 5 of hBM-MSCs. The mice were euthanized 2-24 weeks after transplantation,and gastrocnemius muscle were analyzed for human MyoD, myogenin,desmin,and dystrophin (Dys) expressions by immunohistochemistry and RT-PCR.

RESULTSThe numbers of MyoD-,myogenin-,and desmin-positive cells per 100 hBM-MSCs were 23.5∓5.3, 30.7∓6.2, and 28.4∓5.7, respectively. MyoD, myogenin, and desmin mRNA was observed in passage 5 of hBM-MSCs. After two weeks of hBM-MSCs transplantation,a small number of MyoD-and myogenin-positive cells were observed in skeletal muscle of mdx mice,and desmin-positive cells were observed 4 weeks after transplantation. Expressions of MyoD and myogenin were detected in the muscle of mdx mice 2-4 weeks after hBM-MSCs transplantation, which reached a peak 12-16 weeks later. Desmin was expressed in the muscle of mdx mice 4-8 weeks after transplantation,with much more expression after 16 weeks of transplantation. A small number of Dys-positive cell and Dys mRNA expression were presented in the muscle of mdx mice 4 and 8 weeks after hBM-MSCs transplantation,respectively. The expression of Dys in the muscle of mdx mice increased gradually after transplantation.

CONCLUSIONhBM-MSCs have the potential of myogenic differentiation in vitro and contribute to myogenic conversion in xenogeneic animal,during which the up-regulation of MyoD and myogenin expressions may play an important role.

Animals ; Biomarkers ; Bone Marrow Cells ; cytology ; metabolism ; Cell Differentiation ; Cells, Cultured ; Desmin ; metabolism ; Humans ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Mice ; Mice, Inbred mdx ; Muscle, Skeletal ; cytology ; metabolism ; MyoD Protein ; metabolism ; Myogenin ; metabolism ; Up-Regulation

OBJECTIVETo investigate the differentiation of rat bone marrow mesenchymal stem cells (MSCs) into myocytes and their expression of dystrophin/utrophin after transplantation in mdx mice.

METHODSBrdU-labeled fifth-passage rat MSCs were transplanted in mdx mice with previous total body gamma irradiation (7 Gy). At 4, 8, 12 and 16 weeks after the transplantation, the mice were sacrificed to detect dystrophin/BrdU and utrophin expressions in the gastrocnemius muscle using immunofluorescence assay, RT-PCR and Western blotting. Five normal C57 BL/6 mice and 5 mdx mice served as the positive and negative controls, respectively.

RESULTSFour weeks after MSC transplantation, less than 1% of the muscle fibers of the mdx mice expressed dystrophin, which increased to 15% at 16 weeks. Donor-derived nuclei were detected in both single and clusters of dystrophin-positive fibers. Some BrdU-positive nuclei were centrally located, and some peripherally within myofibers. Utrophin expression decreased over time after transplantation.

CONCLUSIONThe myofibers of mdx mice with MSC transplantation express dystrophin, which is derived partially from the transplanted MSCs. Dystrophin expression from the transplanted MSCs partially inhibits the upregulation of utrophin in mdx mouse muscle, showing a complementary relation between them.

Animals ; Bone Marrow Cells ; cytology ; Cell Differentiation ; physiology ; Dystrophin ; genetics ; metabolism ; Mesenchymal Stem Cell Transplantation ; Mesenchymal Stromal Cells ; cytology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred mdx ; metabolism ; Muscle Fibers, Skeletal ; cytology ; metabolism ; Muscular Dystrophy, Animal ; metabolism ; therapy ; Rats ; Utrophin ; metabolism

Skeletal muscle contains several precursor cells that generate muscle, bone, cartilage and blood cells. Although there are reports that skeletal muscle-derived cells can trans-differentiate into neural-lineage cells, methods for isolating precursor cells, and procedures for successful neural induction have not been fully established. Here, we show that the preplate cell isolation method, which separates cells based on their adhesion characteristics, permits separation of cells possessing neural precursor characteristics from other cells of skeletal muscle tissues. We term these isolated cells skeletal muscle-derived neural precursor cells (SMNPs). The isolated SMNPs constitutively expressed neural stem cell markers. In addition, we describe effective neural induction materials permitting the neuron-like cell differentiation of SMNPs. Treatment with retinoic acid or forskolin facilitated morphological changes in SMNPs; they differentiated into neuron-like cells that possessed specific neuronal markers. These results suggest that the preplate isolation method, and treatment with retinoic acid or forskolin, may provide vital assistance in the use of SMNPs in cell-based therapy of neuronal disease.
Animals ; Antigens, Differentiation/metabolism ; Cell Adhesion ; *Cell Differentiation ; Cell Lineage ; Cell Separation ; Cells, Cultured ; Forskolin/pharmacology ; Mice ; Mice, Inbred ICR ; Muscle, Skeletal/*cytology/metabolism ; Neurons/*cytology/metabolism ; Stem Cells/*cytology/metabolism ; Tretinoin/pharmacology

OBJECTIVETo explore the possible mechanism of the erector spinal muscles in idiopathic scoliosis by comparing the expression and localization of neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) of the thoracic erector spinal muscles on convex side and concave side.

METHODSThe patient group comprised 8 females and 2 males who were scheduled for spinal surgery. The apex of scoliotic curve in these patients arose between T6 and T11. The mean age was 14.3 (range 12-17) years, and the mean Cobb angle was 57.7 degrees (range 45 degrees-85 degrees). Muscle biopsies were taken bilaterally during surgery from the superficial multifidus muscle at the apex of the curve between the 6th and 11th thoracic vertebral levels. Part of the tissue was fixed in formalin and stained with hematoxylin and eosin; the remaining tissue was snap frozen and processed for immunohistochemistry and Western blot. Immunocytochemistry for nNOS and iNOS were performed using the EnVision two-step method. Western blot was done with antibodys to nNOS and iNOS. Immunoreactive bands were visualized by enhanced chemiluminescence according to the manufacturer's specifications (Amersham Corp).

RESULTSnNOS protein in the erector spinal muscles was localized at the sarcolemma. Western blot demonstrated that nNOS protein expression in the concave side of erector spinal muscles is more than that in the convex side. A significant decrease in nNOS protein and activity was found on the convex side of erector spinal muscles from idiopathic scoliosis patients; There was a little immunoreactivity to iNOS in erector spinal muscles. There was little difference in iNOS protein expression between both sides of the curve. Western blot detected the same results.

CONCLUSIONThere is a greater expression of nNOS and iNOS on the concave side than on the convex side, suggesting nNOS and iNOS may play a role in the pathogenesis of idiopathic scoliosis.

Adolescent ; Child ; Female ; Humans ; Immunohistochemistry ; Male ; Muscle, Skeletal ; cytology ; enzymology ; Nitric Oxide Synthase ; analysis ; metabolism ; Nitric Oxide Synthase Type I ; Nitric Oxide Synthase Type II ; Scoliosis ; enzymology

Myostatin (Mstn) is a member of the transforming growth factor-beta superfamily that functions as a negative regulator of skeletal muscle growth and differentiation in mammals. The transcriptional regulation of Mstn is controlled by multiple genes including MEF2, which raise the importance of identifying the binding sites of MEF2 on myostatin promoter region and mechanisms underlying. In this study, we investigated the transcriptional regulation of MEF2 on porcine Mstn promoter activity in C2C12 cells. Sequence analysis of the 1 969 bp porcine Mstn promoter region revealed that it contained three potential MEF2 motifs. Using a serial deletion strategy, we tested the activity of several promoter fragments by luciferase assay. Overexpression of MEF2C, but not MEF2A increased Mstn promoter activity in all the promoter fragments with MEF2 motifs by two to six folds, in both C2C12 myoblasts and myotubes. When we transfected exogenous MEF2C, Mstn mRNA level was also upregulated in C2C12 cells, but the protein level was only significantly increased in myotubes. Thus, we propose that MEF2C could modulate and restrain myogenesis by Mstn activation and Mstn-dependent gene processing in porcine. Our research also provided potential targets and an effective molecule to regulate Mstn expression and gave a new way to explore the functional performance of Mstn.
Animals ; Cells, Cultured ; Gene Expression Regulation ; MEF2 Transcription Factors ; Mice ; Muscle, Skeletal ; metabolism ; Myoblasts ; cytology ; Myogenic Regulatory Factors ; genetics ; physiology ; Myostatin ; genetics ; physiology ; Promoter Regions, Genetic ; Swine

In order to elucidate muscle functional changes by acute reloading, contractile and fatigue properties of the rat soleus muscle were investigated at three weeks of hindlimb suspension and the following 1 hr, 5 hr, 1 d, and 2 weeks of reloading. Compared to age-matched controls, three weeks of unloading caused significant changes in myofibrillar alignments, muscle mass relative to body mass (-43%), normalized tension (-35%), shortening velocity (+143%), and response times. Further significant changes were not observed during early reloading, because the transitional reverse process was gradual rather than abrupt. Although most of the muscle properties returned to the control level after two weeks of reloading, full recovery of the tissue would require more than the two-week period. Delayed recovery due to factors such as myofibrillar arrangement and fatigue resistance was apparent, which should be considered for rehabilitation after a long-term spaceflight or bed-rest.
Animals ; Hindlimb Suspension ; Lactic Acid/metabolism ; Microscopy, Electron ; Muscle Contraction/*physiology ; Muscle Fatigue/*physiology ; Muscle, Skeletal/cytology/*physiology ; Myofibrils/ultrastructure ; Rats ; Rats, Sprague-Dawley ; Research Support, Non-U.S. Gov't ; Weight-Bearing/physiology