Elastic energy storage in rigored skeletal muscle cells under physiological loading conditions

The capability of heavy meromyosin (HMM) to store energy in reversible deformations has been investigated previously; yet, whether HMM is the site of most elastic energy storage in skeletal muscle cells has not been established. We conducted dynamic loading tests on single rigored muscle cells over the physiological range of sarcomere lengths. These tests enabled us to calculate the energy stored in reversible deformations or dissipated in the cell during each cycle of oscillation. Our findings show that these cells are capable of storing approximately 0.5 J . kg-1 of elastic energy during the last 50 ms of passive extension in vivo by agonists and before their own active contraction. Possible sites of this energy storage are HMM subunit 2, the proximal portion of HMM subunit 1, and parallel structures. However, energy storage increases monotonically as myofilament overlap decreases in the physiological range. This negative correlation suggests that HMM subunits are not the primary sites of elastic energy storage. Our electron-microscopic observations show that collagen fibrils at the cell's surface become oriented parallel to the cell's long axis over the range of sarcomere lengths where energy storage increases. This provides a mechanism for the observed increases in elastic energy storage.

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ALY688 elicits adiponectin-mimetic signaling and improves insulin action in skeletal muscle cells

AJP Cell Physiology ◽

10.1152/ajpcell.00603.2020 ◽

2021 ◽

Author(s):

Hye Kyoung Sung ◽

Patricia L. Mitchell ◽

Sean Gross ◽

Andre Marette ◽

Gary Sweeney

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Glucose Uptake ◽

Glucose Transporter ◽

Muscle Cells ◽

Temporal Analysis ◽

Skeletal Muscle Cells ◽

Adiponectin Receptor ◽

Metabolic Effects

Adiponectin is well established to mediate many beneficial metabolic effects, and this has stimulated great interest in development and validation of adiponectin receptor agonists as pharmaceutical tools. This study investigated the effects of ALY688, a peptide-based adiponectin receptor agonist, in rat L6 skeletal muscle cells. ALY688 significantly increased phosphorylation of several adiponectin downstream effectors, including AMPK, ACC and p38MAPK, assessed by immunoblotting and immunofluorescence microscopy. Temporal analysis using cells expressing an Akt biosensor demonstrated that ALY688 enhanced insulin sensitivity. This effect was associated with increased insulin-stimulated Akt and IRS-1 phosphorylation. The functional metabolic significance of these signaling effects was examined by measuring glucose uptake in myoblasts stably overexpressing the glucose transporter GLUT4. ALY688 treatment both increased glucose uptake itself and enhanced insulin-stimulated glucose uptake. In the model of high glucose/high insulin (HGHI)-induced insulin resistant cells, both temporal studies using the Akt biosensor as well as immunoblotting assessing Akt and IRS-1 phosphorylation indicated that ALY688 significantly reduced insulin resistance. Importantly, we observed that ALY688 administration to high-fat high sucrose fed mice also improve glucose handling, validating its efficacy in vivo. In summary, these data indicate that ALY688 activates adiponectin signaling pathways in skeletal muscle, leading to improved insulin sensitivity and beneficial metabolic effects.

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Disparate responses of cultured skeletal muscle cells and growing chicks to tripeptide aldehyde protease inhibitors and an in vivo interaction with ethanol

The Journal of Nutritional Biochemistry ◽

10.1016/0955-2863(92)90035-h ◽

1992 ◽

Vol 3 (6) ◽

pp. 291-297

Author(s):

John C. Fuller ◽

Greg A. Link ◽

Ted W. Huiatt ◽

Jerry L. Sell ◽

Steven Nissen

Keyword(s):

Skeletal Muscle ◽

Protease Inhibitors ◽

Muscle Cells ◽

Skeletal Muscle Cells

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THE FINE STRUCTURE OF EMBRYONIC CHICK SKELETAL MUSCLE CELLS DIFFERENTIATED IN VITRO

The Journal of Cell Biology ◽

10.1083/jcb.35.2.445 ◽

1967 ◽

Vol 35 (2) ◽

pp. 445-453 ◽

Cited By ~ 91

Author(s):

Y. Shimada ◽

D. A. Fischman ◽

A. A. Moscona

Keyword(s):

Electron Microscopy ◽

Skeletal Muscle ◽

Fine Structure ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Chick Embryos ◽

Embryonic Chick ◽

Developing Muscle

Dissociated myoblasts from 12-day chick embryos were cultured in monolayer, and the differentiation of skeletal muscle cells was studied by electron microscopy. The results have revealed a striking ultrastructural similarity between the in vivo and the in vitro developing muscle, particularly with respect to the myofibrils and sarcoplasmic reticulum. This study demonstrates that all the characteristic organelles of mature skeletal muscle can develop in vitro in the absence of nerves.

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Expression of Adiponectin Receptor mRNA in Human Skeletal Muscle Cells Is Related to In Vivo Parameters of Glucose and Lipid Metabolism

Diabetes ◽

10.2337/diabetes.53.9.2195 ◽

2004 ◽

Vol 53 (9) ◽

pp. 2195-2201 ◽

Cited By ~ 86

Author(s):

H. Staiger ◽

S. Kaltenbach ◽

K. Staiger ◽

N. Stefan ◽

A. Fritsche ◽

...

Keyword(s):

Skeletal Muscle ◽

Lipid Metabolism ◽

Human Skeletal Muscle ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Adiponectin Receptor ◽

Receptor Mrna ◽

Glucose And Lipid Metabolism ◽

Human Skeletal Muscle Cells

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Interactions between β-enolase and creatine kinase in the cytosol of skeletal muscle cells

Biochemical Journal ◽

10.1042/bj3460127 ◽

2000 ◽

Vol 346 (1) ◽

pp. 127-131 ◽

Cited By ~ 5

Author(s):

Georges FOUCAULT ◽

Monique VACHER ◽

Sophie CRIBIER ◽

Martine ARRIO-DUPONT

Keyword(s):

Skeletal Muscle ◽

Creatine Kinase ◽

Diffusion Coefficient ◽

Weak Interaction ◽

Satellite Cells ◽

Fringe Pattern ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Skinned Fibres

We studied interactions in vivo between the cytosolic muscle isoform of creatine kinase (M-CK) and the muscle isoform of 2-phospho-D-glycerate hydrolyase (β-enolase) in muscle sarcoplasm by incubating glycerol-skinned fibres with FITC-labelled β-enolase in the presence or absence of free CK. A small amount of bound β-enolase was observed in the presence of large concentrations of CK. The mobility of enolase was measured in cultured satellite cells by modulated-fringe-pattern photobleaching. FITC-labelled β-enolase was totally mobile in both the presence and the absence of CK but its diffusion coefficient was slightly lower in the presence of CK. This suggests a weak interaction in vivo between enolase and CK.

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Monosodium Iodoacetate delays regeneration and inhibits hypertrophy in skeletal muscle cells in vitro

10.1101/577866 ◽

2019 ◽

Author(s):

Rowan P. Rimington ◽

Darren J. Player ◽

Neil R.W. Martin ◽

Mark P. Lewis

Keyword(s):

Skeletal Muscle ◽

Muscle Cells ◽

Rodent Model ◽

Skeletal Muscle Cells ◽

Skeletal Muscle Regeneration ◽

Index Number ◽

Monosodium Iodoacetate ◽

The Impact

AbstractObjectiveOsteoarthritis (OA) is a musculoskeletal disease which contributes to severe morbidity. The monosodium iodoacetate (MIA) rodent model of OA is now well established, however the effect of MIA on surrounding tissues post injection has not been investigated and as such the impact on phenotypic development is unknown. The aim of this investigation was to examine the impact of MIA incubation on skeletal muscle cells in vitro, to provide an indication as to the potential influence of MIA administration of skeletal muscle in vivo.MethodsC2C12 skeletal muscle myotubes were treated with either 4.8μM MIA or 10μM Dexamethasone (DEX, positive atrophic control) up to 72hrs post differentiation and sampled for morphological and mRNA analyses.ResultsSignificant morphological effects (fusion index, number of myotubes and myotube width, p<0.05) were evident, demonstrating a hypertrophic phenotype in control (CON) compared to a hyperplasic phenotype in MIA and DEX. Increases in MAFbx mRNA were also evident between conditions, with post-hoc analysis demonstrating significance between CON and DEX (p<0.001), but not between CON and MIA (p>0.05).ConclusionsThese data indicate a significant impact of both DEX and MIA on regeneration and hypertrophy in vitro and suggest differential activating mechanisms. Future investigations should determine whether skeletal muscle regeneration and hypertrophy is affected in the in vivo rodent model and the potential impact this has on the OA phenotypic outcome.

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Peptide-Functionalized Dendrimer Nanocarriers for Targeted Microdystrophin Gene Delivery

Pharmaceutics ◽

10.3390/pharmaceutics13122159 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2159

Author(s):

Jessica Hersh ◽

José Manuel Condor Capcha ◽

Camila Iansen Irion ◽

Guerline Lambert ◽

Mauricio Noguera ◽

...

Keyword(s):

Skeletal Muscle ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Gene Delivery ◽

Nuclear Membrane ◽

Targeted Delivery ◽

Intracellular Transport ◽

Muscle Cells ◽

Skeletal Muscle Cells

Gene therapy is a good alternative for determined congenital disorders; however, there are numerous limitations for gene delivery in vivo including targeted cellular uptake, intracellular trafficking, and transport through the nuclear membrane. Here, a modified G5 polyamidoamine (G5 PAMAM) dendrimer–DNA complex was developed, which will allow cell-specific targeting to skeletal muscle cells and transport the DNA through the intracellular machinery and the nuclear membrane. The G5 PAMAM nanocarrier was modified with a skeletal muscle-targeting peptide (SMTP), a DLC8-binding peptide (DBP) for intracellular transport, and a nuclear localization signaling peptide (NLS) for nuclear uptake, and polyplexed with plasmid DNA containing the GFP-tagged microdystrophin (µDys) gene. The delivery of µDys has been considered as a therapeutic modality for patients suffering from a debilitating Duchenne muscular dystrophy (DMD) disorder. The nanocarrier–peptide–DNA polyplexes were prepared with different charge ratios and characterized for stability, size, surface charge, and cytotoxicity. Using the optimized nanocarrier polyplexes, the transfection efficiency in vitro was determined by demonstrating the expression of the GFP and the µDys protein using fluorescence and Western blotting studies, respectively. Protein expression in vivo was determined by injecting an optimal nanocarrier polyplex formulation to Duchenne model mice, mdx4Cv. Ultimately, these nanocarrier polyplexes will allow targeted delivery of the microdystrophin gene to skeletal muscle cells and result in improved muscle function in Duchenne muscular dystrophy patients.

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The HIF-1 response to simulated ischemia in mouse skeletal muscle cells neither enhances glycolysis nor prevents myotube cell death

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00892.2006 ◽

2007 ◽

Vol 293 (4) ◽

pp. R1693-R1701 ◽

Cited By ~ 18

Author(s):

Nathalie Dehne ◽

Uta Kerkweg ◽

Teresa Otto ◽

Joachim Fandrey

Keyword(s):

Skeletal Muscle ◽

Cell Death ◽

Lactate Dehydrogenase ◽

Pyruvate Kinase ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Vegf Mrna ◽

Isolated Cells ◽

Simulated Ischemia

Hypoxia-inducible factor (HIF) plays an important role in regulating gene expression in response to ischemia. Although activation of HIF-1 in muscle tissue was found during ischemia in vivo, the meaning and mechanisms in isolated cells are still incompletely understood. We studied activation of HIF-1 in skeletal muscle cells cultured in either their undifferentiated myoblast state or differentiated into myotubes. HIF-1 was activated in myoblasts and myotubes by hypoxia and simulated ischemia. Induction of adrenomedullin mRNA and, to a lesser extent, VEGF mRNA correlated well with the induction of HIF-1α protein in both cell types. Enzymes of glycolysis-like lactate dehydrogenase and pyruvate kinase showed upregulation of their mRNA only under hypoxic conditions but not during simulated ischemia. Phosphofructokinase mRNA showed no significant upregulation at all. Although HIF-1 was activated in myotubes during simulated ischemia, myotubes died preceded by a loss of ATP. Myoblasts survived simulated ischemia with no decrease in ATP or ATP turnover. Furthermore, pharmacological inhibition of HIF-1 hydroxylases by dimethyloxalylglycine (DMOG) increased HIF-1α accumulation and significantly upregulated the expression of adrenomedullin, VEGF, lactate dehydrogenase, and pyruvate kinase in myoblasts and myotubes. However, DMOG provided no protection from cell death. Our data indicate that HIF-1, although activated in myotubes during simulated ischemia, cannot protect against the loss of ATP and cell viability. In contrast, myoblasts survive ischemia and thus may play an important role during regeneration and HIF-1-induced revascularization.

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