scholarly journals Concentration of elongation factor 2 in rat skeletal muscle during protein depletion and re-feeding (Short Communication)

1974 ◽  
Vol 142 (1) ◽  
pp. 185-188 ◽  
Author(s):  
Sunney D. Alexis ◽  
Vernon R. Young ◽  
D. Michael Gill
Keyword(s):  
Skeletal Muscle ◽  
Dietary Protein ◽  
Short Communication ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Elongation Factor ◽  
Rat Skeletal Muscle ◽  
Elongation Factor 2 ◽  
Whole Muscle

Rat skeletal-muscle elongation factor 2 was assayed by causing it to react with NAD+ by using fragment A of diphtheria toxin as the catalyst. Dietary protein restriction decreased the concentration of elongation factor 2 in homogenates of whole muscle. These decreases paralleled a decline in muscle RNA so that the number of molecules of elongation factor 2 per ribosome appeared to be independent of the diet. We conclude that elongation factor 2 is probably not the factor limiting the rate of muscle protein synthesis and is not responsible for the fall in the protein-synthetic rate in vivo observed in the muscles of animals whose dietary protein intake is inadequate.

scholarly journals Posttranscriptional control of embryonic rat skeletal muscle protein synthesis. Control at the level of translation by endogenous RNA.

1988 ◽  
Vol 107 (3) ◽  
pp. 1085-1098 ◽  
Author(s):  
C R Vanderburg ◽  
M A Nathanson
Keyword(s):  
Skeletal Muscle ◽  
Cell Differentiation ◽  
Muscle Cell ◽  
Translational Control ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Rat Skeletal Muscle ◽  
Total Rna ◽  
Muscle Cell Differentiation

The onset of muscle cell differentiation is associated with increased transcription of muscle-specific mRNA. Studies from this laboratory using 19-d embryonic rat skeletal muscle, suggest that additional, posttranscriptional controls regulate maturation of muscle tissue via a quantitative effect upon translation, and that the regulatory component may reside within the poly A- RNA pool (Nathanson, M.A., E.W. Bush, and C. Vanderburg. 1986. J. Biol. Chem. 261:1477-1486). To further characterize muscle cell translational control, embryonic and adult total RNA were separated into oligo(dT)cellulose-bound (poly A+) and -unbound (poly A-) pools. Unbound material was subjected to agarose gel electrophoresis to resolve constituents of varying molecular size and mechanically cut into five fractions. Material of each fraction was electroeluted and recovered by precipitation. Equivalent loads of total RNA from 19-20-d embryonic rat skeletal muscle exhibited a 40% translational inhibition in comparison to its adult counterpart. Inhibition was not due to decreased message abundance because embryonic, as well as adult muscle, contained equivalent proportions of poly A+ mRNA. An inhibition assay, based upon the translatability of adult RNA and its inhibition by embryonic poly A- RNA, confirmed that inhibition was associated with a 160-2,000-nt poly A- fraction. Studies on the chemical composition of this fraction confirmed its RNA composition, the absence of ribonucleoprotein, and that its activity was absent from similarly fractionated adult RNA. Rescue of inhibition could be accomplished by addition of extra lysate or mRNA; however, smaller proportions of lysate were required, suggesting a strong interaction of inhibitor and components of the translational apparatus. Additional studies demonstrated that the inhibitor acted at the level of initiation, in a dose-dependent fashion. The present studies confirm the existence of translational control in skeletal muscle and suggest that it operates at the embryonic to adult transition. A model of muscle cell differentiation, based upon transcriptional control at the myoblast level, followed by translational regulation at the level of the postmitotic myoblast and/or myotube, is proposed.

scholarly journals Novel insights into the regulation of skeletal muscle protein synthesis as revealed by a new nonradioactive in vivo technique

2010 ◽  
Vol 25 (3) ◽  
pp. 1028-1039 ◽  
Author(s):  
Craig A. Goodman ◽  
Danielle M. Mabrey ◽  
John W. Frey ◽  
Man Hing Miu ◽  
Enrico K. Schmidt ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis

Beyond muscle hypertrophy: why dietary protein is important for endurance athletes

2014 ◽  
Vol 39 (9) ◽  
pp. 987-997 ◽  
Author(s):  
Daniel R. Moore ◽  
Donny M. Camera ◽  
Jose L. Areta ◽  
John A. Hawley
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Dietary Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Recovery Period ◽  
Essential Element ◽  
Skeletal Muscle Protein ◽  
Muscle Remodelling

Recovery from the demands of daily training is an essential element of a scientifically based periodized program whose twin goals are to maximize training adaptation and enhance performance. Prolonged endurance training sessions induce substantial metabolic perturbations in skeletal muscle, including the depletion of endogenous fuels and damage/disruption to muscle and body proteins. Therefore, increasing nutrient availability (i.e., carbohydrate and protein) in the post-training recovery period is important to replenish substrate stores and facilitate repair and remodelling of skeletal muscle. It is well accepted that protein ingestion following resistance-based exercise increases rates of skeletal muscle protein synthesis and potentiates gains in muscle mass and strength. To date, however, little attention has focused on the ability of dietary protein to enhance skeletal muscle remodelling and stimulate adaptations that promote an endurance phenotype. The purpose of this review is to critically discuss the results of recent studies that have examined the role of dietary protein for the endurance athlete. Our primary aim is to consider the results from contemporary investigations that have advanced our knowledge of how the manipulation of dietary protein (i.e., amount, type, and timing of ingestion) can facilitate muscle remodelling by promoting muscle protein synthesis. We focus on the role of protein in facilitating optimal recovery from, and promoting adaptations to strenuous endurance-based training.

scholarly journals Effect of electrical stimulation-induced resistance exercise on mitochondrial fission and fusion proteins in rat skeletal muscle

2015 ◽  
Vol 40 (11) ◽  
pp. 1137-1142 ◽  
Author(s):  
Yu Kitaoka ◽  
Riki Ogasawara ◽  
Yuki Tamura ◽  
Satoshi Fujita ◽  
Hideo Hatta
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Resistance Exercise ◽  
Mitochondrial Function ◽  
Muscle Protein ◽  
Mitochondrial Dynamics ◽  
Muscle Protein Synthesis ◽  
Mitochondrial Fission ◽  
Dynamic Networks ◽  
Rat Skeletal Muscle

It is well known that resistance exercise increases muscle protein synthesis and muscle strength. However, little is known about the effect of resistance exercise on mitochondrial dynamics, which is coupled with mitochondrial function. In skeletal muscle, mitochondria exist as dynamic networks that are continuously remodeling through fusion and fission. The purpose of this study was to investigate the effect of acute and chronic resistance exercise, which induces muscle hypertrophy, on the expression of proteins related to mitochondrial dynamics in rat skeletal muscle. Resistance exercise consisted of maximum isometric contraction, which was induced by percutaneous electrical stimulation of the gastrocnemius muscle. Our results revealed no change in levels of proteins that regulate mitochondrial fission (Fis1 and Drp1) or fusion (Opa1, Mfn1, and Mfn2) over the 24-h period following acute resistance exercise. Phosphorylation of Drp1 at Ser616 was increased immediately after exercise (P < 0.01). Four weeks of resistance training (3 times/week) increased Mfn1 (P < 0.01), Mfn2 (P < 0.05), and Opa1 (P < 0.01) protein levels without altering mitochondrial oxidative phosphorylation proteins. These observations suggest that resistance exercise has little effect on mitochondrial biogenesis but alters the expression of proteins involved in mitochondrial fusion and fission, which may contribute to mitochondrial quality control and improved mitochondrial function.

scholarly journals The sedimentation of rat skeletal-muscle ribosomes. Effect of hydrocortisone, insulin and diet

1968 ◽  
Vol 106 (4) ◽  
pp. 913-919 ◽  
Author(s):  
V. R. Young ◽  
S. C. Chen ◽  
Jane Macdonald
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Sucrose Gradient ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Insulin Injection ◽  
Sedimentation Analysis ◽  
Rat Skeletal Muscle ◽  
Protein Free Diet ◽  
Post Mitochondrial Supernatant

1. The influence of hydrocortisone, insulin and diet on the size distribution of ribosomes in a post-mitochondrial supernatant prepared from rat skeletal muscle was studied by sedimentation analysis with a linear 15–40% (w/v) sucrose gradient. 2. Within 4hr. after the injection of 5mg. of hydrocortisone to well-nourished rats, a decrease in the yield per g. of muscle and proportion of total RNA due to polyribosomes was observed. Similar results were obtained in rats given a protein-free diet for 3 days before administration of the hormone. 3. Insulin injection increased the yield and proportion of polyribosomes within 2hr. and decreased the proportion of the lighter ribosomal aggregates. Similar results were noted in rats given a protein-free diet for 3 days before injection. A protein-free diet given for 3 days decreased the yield and proportion of polyribosomes. Insulin did not increase the yield of polyribosomes if rats were starved for 52hr. before injection, but decreased the yield and proportion of the lighter ribosome species. 4. A 52hr. period of starvation or 2,4-dinitrophenol (15mg./kg. body wt.) given 1hr. before the rats were killed resulted in a decreased yield and proportion of polyribosomes, and, within 6hr. of re-feeding the rats with protein-free diets, an increased concentration of polyribosomes was noted. 5. The effects of a protein-free diet, hydrocortisone and insulin on the sedimentation of muscle ribosomes were found to be in accord with their net effects on muscle protein synthesis.

scholarly journals Dietary protein, exercise, ageing and physical inactivity: interactive influences on skeletal muscle proteostasis

2020 ◽  
pp. 1-12
Author(s):  
Colleen S. Deane ◽  
Isabel A. Ely ◽  
Daniel J. Wilkinson ◽  
Kenneth Smith ◽  
Bethan E. Phillips ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dietary Protein ◽  
Protein Intake ◽  
Physical Inactivity ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Blood Flow ◽  
Regulatory Protein ◽  
Anabolic Resistance ◽  
Short Period

Dietary protein is a pre-requisite for the maintenance of skeletal muscle mass; stimulating increases in muscle protein synthesis (MPS), via essential amino acids (EAA), and attenuating muscle protein breakdown, via insulin. Muscles are receptive to the anabolic effects of dietary protein, and in particular the EAA leucine, for only a short period (i.e. about 2–3 h) in the rested state. Thereafter, MPS exhibits tachyphylaxis despite continued EAA availability and sustained mechanistic target of rapamycin complex 1 signalling. Other notable characteristics of this ‘muscle full’ phenomenon include: (i) it cannot be overcome by proximal intake of additional nutrient signals/substrates regulating MPS; meaning a refractory period exists before a next stimulation is possible, (ii) it is refractory to pharmacological/nutraceutical enhancement of muscle blood flow and thus is not induced by muscle hypo-perfusion, (iii) it manifests independently of whether protein intake occurs in a bolus or intermittent feeding pattern, and (iv) it does not appear to be dependent on protein dose per se. Instead, the main factor associated with altering muscle full is physical activity. For instance, when coupled to protein intake, resistance exercise delays the muscle full set-point to permit additional use of available EAA for MPS to promote muscle remodelling/growth. In contrast, ageing is associated with blunted MPS responses to protein/exercise (anabolic resistance), while physical inactivity (e.g. immobilisation) induces a premature muscle full, promoting muscle atrophy. It is crucial that in catabolic scenarios, anabolic strategies are sought to mitigate muscle decline. This review highlights regulatory protein turnover interactions by dietary protein, exercise, ageing and physical inactivity.

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