scholarly journals Skeletal muscle and resistance exercise training; the role of protein synthesis in recovery and remodeling

2017 ◽  
Vol 122 (3) ◽  
pp. 541-548 ◽  
Author(s):  
Chris McGlory ◽  
Michaela C. Devries ◽  
Stuart M. Phillips
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Turnover ◽  
Potential Role ◽  
Muscle Protein ◽  
Short Review ◽  
Translational Efficiency ◽  
Exercise Science ◽  
Resistance Exercise Training

Exercise results in the rapid remodeling of skeletal muscle. This process is underpinned by acute and chronic changes in both gene and protein synthesis. In this short review we provide a brief summary of our current understanding regarding how exercise influences these processes as well as the subsequent impact on muscle protein turnover and resultant shift in muscle phenotype. We explore concepts of ribosomal biogenesis and the potential role of increased translational capacity vs. translational efficiency in contributing to muscular hypertrophy. We also examine whether high-intensity sprinting-type exercise promotes changes in protein turnover that lead to hypertrophy or merely a change in mitochondrial content. Finally, we propose novel areas for future study that will fill existing knowledge gaps in the fields of translational research and exercise science.

Skeletal and cardiac muscle protein turnover during cold acclimation in young rats

2000 ◽  
Vol 278 (3) ◽  
pp. R705-R711 ◽  
Author(s):  
T. A. McAllister ◽  
J. R. Thompson ◽  
S. E. Samuels
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Cold Acclimation ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Turnover ◽  
Protein Mass ◽  
The Absolute

The effect of long-term cold exposure on skeletal and cardiac muscle protein turnover was investigated in young growing animals. Two groups of 36 male 28-day-old rats were maintained at either 5°C (cold) or 25°C (control). Rates of protein synthesis and degradation were measured in vivo on days 5, 10, 15, and 20. Protein mass by day 20 was ∼28% lower in skeletal muscle (gastrocnemius and soleus) and ∼24% higher in heart in cold compared with control rats ( P < 0.05). In skeletal muscle, the fractional rates of protein synthesis ( k syn) and degradation ( k deg) were not significantly different between cold and control rats, although k syn was lower (approximately −26%) in cold rats on day 5; consequent to the lower protein mass, the absolute rates of protein synthesis (approximately −21%; P < 0.05) and degradation (approximately −13%; P < 0.1) were lower in cold compared with control rats. In heart, overall, k syn(approximately +12%; P < 0.1) and k deg(approximately +22%; P < 0.05) were higher in cold compared with control rats; consequently, the absolute rates of synthesis (approximately +44%) and degradation (approximately +54%) were higher in cold compared with control rats ( P < 0.05). Plasma triiodothyronine concentration was higher ( P < 0.05) in cold compared with control rats. These data indicate that long-term cold acclimation in skeletal muscle is associated with the establishment of a new homeostasis in protein turnover with decreased protein mass and normal fractional rates of protein turnover. In heart, unlike skeletal muscle, rates of protein turnover did not appear to immediately return to normal as increased rates of protein turnover were observed beyond day 5. These data also indicate that increased rates of protein turnover in skeletal muscle are unlikely to contribute to increased metabolic heat production during cold acclimation.

scholarly journals Advances in the Role of Leucine-Sensing in the Regulation of Protein Synthesis in Aging Skeletal Muscle

2021 ◽  
Vol 9 ◽  
Author(s):  
Yan Zhao ◽  
Jason Cholewa ◽  
Huayu Shang ◽  
Yueqin Yang ◽  
Xiaomin Ding ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Therapeutic Potential ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Trna Synthetase ◽  
Limiting Factor ◽  
Anabolic Resistance ◽  
Age Related

Skeletal muscle anabolic resistance (i.e., the decrease in muscle protein synthesis (MPS) in response to anabolic stimuli such as amino acids and exercise) has been identified as a major cause of age-related sarcopenia, to which blunted nutrition-sensing contributes. In recent years, it has been suggested that a leucine sensor may function as a rate-limiting factor in skeletal MPS via small-molecule GTPase. Leucine-sensing and response may therefore have important therapeutic potential in the steady regulation of protein metabolism in aging skeletal muscle. This paper systematically summarizes the three critical processes involved in the leucine-sensing and response process: (1) How the coincidence detector mammalian target of rapamycin complex 1 localizes on the surface of lysosome and how its crucial upstream regulators Rheb and RagB/RagD interact to modulate the leucine response; (2) how complexes such as Ragulator, GATOR, FLCN, and TSC control the nucleotide loading state of Rheb and RagB/RagD to modulate their functional activity; and (3) how the identified leucine sensor leucyl-tRNA synthetase (LARS) and stress response protein 2 (Sestrin2) participate in the leucine-sensing process and the activation of RagB/RagD. Finally, we discuss the potential mechanistic role of exercise and its interactions with leucine-sensing and anabolic responses.

scholarly journals Regulation of Ribosome Biogenesis in Skeletal Muscle Hypertrophy

Physiology ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 30-42 ◽  
Author(s):  
Vandré Casagrande Figueiredo ◽  
John J. McCarthy
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Ribosome Biogenesis ◽  
Muscle Hypertrophy ◽  
Muscle Growth ◽  
Translational Efficiency ◽  
Resistance Exercise Training ◽  
Skeletal Muscle Growth ◽  
Skeletal Muscle Hypertrophy ◽  
Important Regulator

The ribosome is the enzymatic macromolecular machine responsible for protein synthesis. The rates of protein synthesis are primarily dependent on translational efficiency and capacity. Ribosome biogenesis has emerged as an important regulator of skeletal muscle growth and maintenance by altering the translational capacity of the cell. Here, we provide evidence to support a central role for ribosome biogenesis in skeletal muscle growth during postnatal development and in response to resistance exercise training. Furthermore, we discuss the cellular signaling pathways regulating ribosome biogenesis, discuss how myonuclear accretion affects translational capacity, and explore future areas of investigation within the field.

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 Exercise-Induced Muscle Damage and Hypertrophy: A Closer Look Reveals the Jury is Still Out

2018 ◽  
Author(s):  
Brad Jon Schoenfeld ◽  
Bret Contreras
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Training ◽  
Muscle Damage ◽  
Muscle Hypertrophy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Hypertrophy ◽  
Exercise Induced

This letter is a response to the paper by Damas et al (2017) titled, “The development of skeletal muscle hypertrophy through resistance training: the role of muscle damage and muscle protein synthesis,” which, in part, endeavored to review the role of exercise-induced muscle damage on muscle hypertrophy. We feel there are a number of issues in interpretation of research and extrapolation that preclude drawing the inference expressed in the paper that muscle damage neither explains nor potentiates increases in muscle hypertrophy. The intent of our letter is not to suggest that a causal role exists between hypertrophy and microinjury. Rather, we hope to provide balance to the evidence presented and offer the opinion that the jury is still very much out as to providing answers on the topic.

scholarly journals Serum extracellular vesicle miR-203a-3p content is associated with skeletal muscle mass and protein turnover during disuse atrophy and regrowth

2020 ◽  
Vol 319 (2) ◽  
pp. C419-C431
Author(s):  
Douglas W. Van Pelt ◽  
Ivan J. Vechetti ◽  
Marcus M. Lawrence ◽  
Kathryn L. Van Pelt ◽  
Parth Patel ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Weight Bearing ◽  
Mirna Content ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Small noncoding microRNAs (miRNAs) are important regulators of skeletal muscle size, and circulating miRNAs within extracellular vesicles (EVs) may contribute to atrophy and its associated systemic effects. The purpose of this study was to understand how muscle atrophy and regrowth alter in vivo serum EV miRNA content. We also associated changes in serum EV miRNA with protein synthesis, protein degradation, and miRNA within muscle, kidney, and liver. We subjected adult (10 mo) F344/BN rats to three conditions: weight bearing (WB), hindlimb suspension (HS) for 7 days to induce muscle atrophy, and HS for 7 days followed by 7 days of reloading (HSR). Microarray analysis of EV miRNA content showed that the overall changes in serum EV miRNA were predicted to target major anabolic, catabolic, and mechanosensitive pathways. MiR-203a-3p was the only miRNA demonstrating substantial differences in HS EVs compared with WB. There was a limited association of EV miRNA content to the corresponding miRNA content within the muscle, kidney, or liver. Stepwise linear regression demonstrated that EV miR-203a-3p was correlated with muscle mass and muscle protein synthesis and degradation across all conditions. Finally, EV miR-203a-3p expression was significantly decreased in human subjects who underwent unilateral lower limb suspension (ULLS) to induce muscle atrophy. Altogether, we show that serum EV miR-203a-3p expression is related to skeletal muscle protein turnover and atrophy. We suggest that serum EV miR-203a-3p content may be a useful biomarker and future work should investigate whether serum EV miR-203a-3p content is mechanistically linked to protein synthesis and degradation.

Role of eIF4E in stimulation of protein synthesis by IGF-I in perfused rat skeletal muscle

2000 ◽  
Vol 278 (1) ◽  
pp. E58-E64 ◽  
Author(s):  
Thomas C. Vary ◽  
Leonard S. Jefferson ◽  
Scot R. Kimball
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Initiation Factor ◽  
Translational Efficiency ◽  
Rat Skeletal Muscle ◽  
Phosphorylation State ◽  
Factor I ◽  
Igf I ◽  
Stimulation Of

Insulin-like growth factor I (IGF-I) promotes anabolism by stimulating protein synthesis in skeletal muscle. In the present study, we have examined mechanisms by which IGF-I stimulates protein synthesis in skeletal muscle with a perfused rat hindlimb preparation. IGF-I (10 nM) stimulated protein synthesis over 2.7-fold. Total RNA content was unaffected, but translational efficiency was increased by IGF-I. We next examined the effect of IGF-I on eukaryotic initiation factor (eIF) 4E as a mechanism regulating translation initiation. IGF-I did not alter either the amount of eIF4E associated with the eIF4E binding protein 4E-BP1 or the phosphorylation state of 4E-BP1. Likewise, the phosphorylation state of eIF4E was unaltered by IGF-I. In contrast, the amount of eIF4E bound to eIF4G was increased threefold by IGF-I. We conclude that IGF-I regulates protein synthesis in skeletal muscle by enhancing formation of the active eIF4E ⋅ eIF4G complex.

scholarly journals Skeletal Muscle Recovery from Disuse Atrophy: Protein Turnover Signaling and Strategies for Accelerating Muscle Regrowth

2020 ◽  
Vol 21 (21) ◽  
pp. 7940
Author(s):  
Timur M. Mirzoev
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Mass ◽  
Mechanical Loading ◽  
Protein Turnover ◽  
Skeletal Muscle Mass ◽  
Molecular Mechanisms ◽  
Muscle Protein ◽  
Muscle Recovery ◽  
Mechanical Unloading

Skeletal muscle fibers have a unique capacity to adjust their metabolism and phenotype in response to alternations in mechanical loading. Indeed, chronic mechanical loading leads to an increase in skeletal muscle mass, while prolonged mechanical unloading results in a significant decrease in muscle mass (muscle atrophy). The maintenance of skeletal muscle mass is dependent on the balance between rates of muscle protein synthesis and breakdown. While molecular mechanisms regulating protein synthesis during mechanical unloading have been relatively well studied, signaling events implicated in protein turnover during skeletal muscle recovery from unloading are poorly defined. A better understanding of the molecular events that underpin muscle mass recovery following disuse-induced atrophy is of significant importance for both clinical and space medicine. This review focuses on the molecular mechanisms that may be involved in the activation of protein synthesis and subsequent restoration of muscle mass after a period of mechanical unloading. In addition, the efficiency of strategies proposed to improve muscle protein gain during recovery is also discussed.

TNF-α impairs heart and skeletal muscle protein synthesis by altering translation initiation

2002 ◽  
Vol 282 (2) ◽  
pp. E336-E347 ◽  
Author(s):  
Charles H. Lang ◽  
Robert A. Frost ◽  
Angus C. Nairn ◽  
David A. MacLean ◽  
Thomas C. Vary
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Translation Initiation ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mrna Translation ◽  
Translational Efficiency ◽  
Skeletal Muscle Protein ◽  
Phosphorylation State ◽  
Tnf Α

This study examined potential mechanisms contributing to the inhibition of protein synthesis in skeletal muscle and heart after administration of tumor necrosis factor (TNF)-α. Rats had vascular catheters implanted, and TNF-α was infused continuously for 24 h. TNF-α decreased in vivo-determined rates of global protein synthesis in gastrocnemius (39%) and heart (25%). The TNF-α-induced decrease in protein synthesis in the gastrocnemius involved a reduction in the synthesis of both myofibrillar and sarcoplasmic proteins. To identify potential mechanisms responsible for regulating mRNA translation, we examined several eukaryotic initiation factors (eIFs) and elongation factors (eEFs). TNF-α decreased the activity of eIF-2B in muscle (39%) but not in heart. This diminished activity was not caused by a reduction in the content of eIF-2Bε or the content and phosphorylation state of eIF-2α. Skeletal muscle and heart from TNF-α-treated rats demonstrated 1) an increased binding of the translation repressor 4E-binding protein-1 (4E-BP1) with eIF-4E, 2) a decreased amount of eIF-4E associated with eIF-4G, and 3) a decreased content of the hyperphosphorylated γ-form of 4E-BP1. In contrast, the infusion of TNF-α did not alter the content of eEF-1α or eEF-2, or the phosphorylation state of eEF-2. In summary, these data suggest that TNF-α impairs skeletal muscle and heart protein synthesis, at least in part, by decreasing mRNA translational efficiency resulting from an impairment in translation initiation associated with alterations in eIF-4E availability.

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