scholarly journals Essential Amino Acid-Enriched Diet Alleviates Dexamethasone-Induced Loss of Muscle Mass and Function through Stimulation of Myofibrillar Protein Synthesis and Improves Glucose Metabolism in Mice

Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 84
Author(s):  
Yeongmin Kim ◽  
Sanghee Park ◽  
Jinseok Lee ◽  
Jiwoong Jang ◽  
Jiyeon Jung ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Glucose Metabolism ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Myofibrillar Protein ◽  
Treadmill Running ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Myofibrillar Protein Synthesis ◽  
Stimulation Of

Dexamethasone (DEX) induces dysregulation of protein turnover, leading to muscle atrophy and impairment of glucose metabolism. Positive protein balance, i.e., rate of protein synthesis exceeding rate of protein degradation, can be induced by dietary essential amino acids (EAAs). In this study, we investigated the roles of an EAA-enriched diet in the regulation of muscle proteostasis and its impact on glucose metabolism in the DEX-induced muscle atrophy model. Mice were fed normal chow or EAA-enriched chow and were given daily injections of DEX over 10 days. We determined muscle mass and functions using treadmill running and ladder climbing exercises, protein kinetics using the D2O labeling method, molecular signaling using immunoblot analysis, and glucose metabolism using a U-13C6 glucose tracer during oral glucose tolerance test (OGTT). The EAA-enriched diet increased muscle mass, strength, and myofibrillar protein synthesis rate, concurrent with improved glucose metabolism (i.e., reduced plasma insulin concentrations and increased insulin sensitivity) during the OGTT. The U-13C6 glucose tracing revealed that the EAA-enriched diet increased glucose uptake and subsequent glycolytic flux. In sum, our results demonstrate a vital role for the EAA-enriched diet in alleviating the DEX-induced muscle atrophy through stimulation of myofibrillar proteins synthesis, which was associated with improved glucose metabolism.

scholarly journals Stimulation of skeletal muscle myofibrillar protein synthesis, p70 S6 kinase phosphorylation, and ribosomal protein S6 phosphorylation by inhibition of myostatin in mature mice

2009 ◽  
Vol 296 (3) ◽  
pp. E567-E572 ◽  
Author(s):  
Stephen Welle ◽  
Kerri Burgess ◽  
Sangeeta Mehta
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Myofibrillar Protein ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
S6 Kinase ◽  
P70 S6 Kinase ◽  
Ribosomal Protein S6 ◽  
The Mean ◽  
Myofibrillar Protein Synthesis

Knocking out myostatin activity during development increases the rate of muscle protein synthesis. The present study was done to determine whether postdevelopmental loss of myostatin activity stimulates myofibrillar protein synthesis and the phosphorylation of some of the proteins involved in regulation of protein synthesis rate. Myostatin activity was inhibited for 4 days, in 4- to 5-mo-old male mice, with injections of an anti-myostatin antibody (JA16). The mean myofibrillar synthesis rate increased 19% ( P < 0.01) relative to the mean rate in saline-treated mice, as determined by incorporation of deuterium-labeled phenylalanine. JA16 increased phosphorylation of p70 S6 kinase (S6K) and ribosomal protein S6 (rpS6) 1.9-fold ( P < 0.05). It did not affect phosphorylation of eukaryotic initiation factor 4E-binding protein-1 or Akt. Microarrays and real-time PCR analyses indicated that JA16 administration did not selectively enrich levels of mRNAs encoding myofibrillar proteins, ribosomal proteins, or translation initiation and elongation factors. Rapamycin treatment did not affect the rate of myofibrillar protein synthesis whether or not the mice received JA16 injections, although it eliminated the phosphorylation of S6K and rpS6. We conclude that the normal level of myostatin activity in mature muscle is sufficient to inhibit myofibrillar synthesis rate and phosphorylation of S6K and rpS6. Reversal of the inhibition of myofibrillar synthesis with an anti-myostatin antibody is not dependent on mTOR activation.

scholarly journals Altered anabolic signalling and reduced stimulation of myofibrillar protein synthesis after feeding and resistance exercise in people with obesity

2018 ◽  
Vol 596 (21) ◽  
pp. 5119-5133 ◽  
Author(s):  
Joseph W. Beals ◽  
Sarah K. Skinner ◽  
Colleen F. McKenna ◽  
Elizabeth G. Poozhikunnel ◽  
Samee A. Farooqi ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Myofibrillar Protein ◽  
Anabolic Signalling ◽  
Myofibrillar Protein Synthesis ◽  
Stimulation Of

Regulation of myofibrillar protein turnover during maturation in normal and undernourished rat pups

2000 ◽  
Vol 278 (4) ◽  
pp. R845-R854 ◽  
Author(s):  
Marta L. Fiorotto ◽  
Teresa A. Davis ◽  
Peter J. Reeds
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Myofibrillar Protein ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Myofibrillar Proteins ◽  
Sarcoplasmic Proteins ◽  
Rat Pups ◽  
Sarcoplasmic Protein ◽  
Degradation Rates

The study tested the hypothesis that a higher rate of myofibrillar than sarcoplasmic protein synthesis is responsible for the rapid postdifferentiation accumulation of myofibrils and that an inadequate nutrient intake will compromise primarily myofibrillar protein synthesis. Myofibrillar (total and individual) and sarcoplasmic protein synthesis, accretion, and degradation rates were measured in vivo in well-nourished (C) rat pups at 6, 15, and 28 days of age and compared at 6 and 15 days of age with pups undernourished (UN) from birth. In 6-day-old C pups, a higher myofibrillar than sarcoplasmic protein synthesis rate accounted for the greater deposition of myofibrillar than sarcoplasmic proteins. The fractional synthesis rates of both protein compartments decreased with age, but to a greater degree for myofibrillar proteins (−54 vs. −42%). These decreases in synthesis rates were partially offset by reductions in degradation rates, and from 15 days, myofibrillar and sarcoplasmic proteins were deposited in constant proportion to one another. Undernutrition reduced both myofibrillar and sarcoplasmic protein synthesis rates, and the effect was greater at 6 (−25%) than 15 days (−15%). Decreases in their respective degradation rates minimized the effect of undernutrition on sarcoplasmic protein accretion from 4 to 8 days and on myofibrillar proteins from 13 to 17 days. Although these adaptations in protein turnover reduced overall growth of muscle mass, they mitigated the effects of undernutrition on the normal maturational changes in myofibrillar protein concentration.

scholarly journals Effects of Salmon Ingestion on Post-Exercise Muscle Protein Synthesis: Exploration of Whole Protein Foods Versus Isolated Nutrients

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 650-650
Author(s):  
Kevin Paulussen ◽  
Amadeo Salvador ◽  
Colleen McKenna ◽  
Susannah Scaroni ◽  
Alexander Ulanov ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Myofibrillar Protein ◽  
Post Exercise ◽  
Exercise Muscle ◽  
Amino Acid Concentrations ◽  
Myofibrillar Protein Synthesis ◽  
Stimulation Of

Abstract Objectives Healthy eating patterns consist of eating whole foods as opposed to single nutrients. The maintenance of skeletal muscle mass is of particular interest to overall health. As such, there is a need to underpin the role of eating nutrients within their natural whole-food matrix versus isolated nutrients on the regulation of postprandial muscle protein synthesis rates. This study assessed the effects of eating salmon, a potential food within a healthy Mediterranean style eating pattern, on the stimulation of post-exercise muscle protein synthesis rates versus eating these same nutrients in isolation in healthy young adults. Methods In a crossover design, 10 recreationally active adults (24 ± 4 y; 5 M, 5 F) performed an acute bout of resistance exercise followed by the ingestion of salmon (SAL) (20.5 g protein and 7.5 g fat) or its matched constituents in the form of crystalline amino acids and fish oil (ISO). Blood and muscle biopsies were collected at rest and after exercise at 2 and 5 h during primed continuous infusions of L-[ring-2H5]phenylalanine for the measurement of myofibrillar protein synthesis and plasma amino acid profiles. Data were analyzed by using a 2-factor (time × condition) repeated-measures ANOVA with Tukey's post hoc test. Results Plasma essential amino acid concentrations increased to a similar extent in both SAL and ISO during the postprandial period (P &gt; 0.05). Likewise, postprandial plasma leucine concentrations did not differ between nutrient condition (P &gt; 0.05). The post-exercise myofibrillar protein synthetic responses were similarly stimulated in both nutrition conditions early (0–2 h; 0.079 ± 0.039%/h (SAL) compared to 0.071 ± 0.078%/h (ISO); P = 0.64) and returned to baseline later (2–5 h; 0.046 ± 0.020%/h (SAL) compared to 0.038 ± 0.025%/h (ISO); P = 0.90). Similarly, there were no differences in the stimulation of myofibrillar protein synthesis rates between SAL and ISO during the entire 0–5 h recovery period (0.058 ± 0.024%/h compared to 0.045 ± 0.027%/h, respectively; P = 0.66). Conclusions We show that the ingestion of salmon or its isolated nutrients increases plasma amino acid concentrations and enhances the stimulation of post-exercise muscle protein synthesis rates with no differences in the temporal or cumulative responses in healthy young adults. Funding Sources USDA National Institute of Food and Agriculture Hatch project.

scholarly journals Protein synthesis, myosin ATPase activity and myofibrillar protein composition in hearts from tumour-bearing rats and mice

1989 ◽  
Vol 264 (1) ◽  
pp. 191-198 ◽  
Author(s):  
C Drott ◽  
C Lönnroth ◽  
K Lundholm
Keyword(s):  
Protein Synthesis ◽  
Atpase Activity ◽  
Protein Composition ◽  
Myofibrillar Protein ◽  
Myosin Atpase ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Tumour Bearing ◽  
Myosin Atpase Activity ◽  
Rats And Mice

Growing rats and adult weight-stable mice bearing a transplantable methylcholanthrene-induced sarcoma were compared with animals with various states of malnutrition. Heart protein synthesis was measured in vivo. Myocardial RNA, myofibrillar protein composition and the Ca2+-activated ATPase activity in heavy chains of native myosin were measured. ‘Fingerprints’ were made from myosin by trypsin treatment to evaluate possible structural changes in the protein. Cardiac protein-synthesis rate was decreased by 20% in growing tumour-bearing rats, by 35% in protein-malnourished (rats) and by 47% in starved rats, compared with freely fed controls (P less than 0.05). Adult tumour-bearing mice showed no significant decrease in myocardial protein synthesis. Pair-weighed control mice had significantly depressed heart protein synthesis. Protein translational efficiency was maintained in both tumour-bearing rats and mice, but was decreased in several groups of malnourished control animals. The Ca2+-activated myosin ATPase activity was decreased in all groups of malnourished animals, including tumour-bearing mice and rats, without any evidence of a change in cardiac isomyosin composition. We conclude that loss of cardiac muscle mass in tumour disease is communicated by both depressed synthesis and increased degradation largely owing to anorexia and host malnutrition. Increased adrenergic sensitivity in hearts from tumour-bearing and malnourished animals is not communicated by increased Ca2+-activated ATPase activity. This may be down-regulated in all groups with malnutrition, without any observable alterations in the isomyosin profile.

Myofibrillar protein synthesis in young and old human subjects after three months of resistance training

1995 ◽  
Vol 268 (3) ◽  
pp. E422-E427 ◽  
Author(s):  
S. Welle ◽  
C. Thornton ◽  
M. Statt
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Myofibrillar Protein ◽  
Whole Body ◽  
Synthesis Rate ◽  
Vastus Lateralis Muscle ◽  
Body Protein ◽  
Men And Women ◽  
Older Subjects ◽  
Myofibrillar Protein Synthesis

Muscle protein synthesis is slower in healthy older men and women than in young adults, but whether this results from relative disuse rather than aging is unclear. The present study was done to examine rates of myofibrillar protein synthesis before and after a 3-mo progressive resistance exercise program in young and old men and women. Protein synthesis was determined by incorporation of the tracer L-[1-13C]leucine into myofibrillar proteins obtained from the vastus lateralis muscle by needle biopsy. Before exercise, mean fractional myofibrillar synthesis was 33% slower (P < 0.01) in nine older subjects (62-72 yr old, 5 men and 4 women) than in 9 young subjects (22-31 yr old, 5 men and 4 women). Initial strength, as determined by three-repetition-maximum tests, was significantly less in the older group. Strength and training weights increased similarly in young and old groups, when expressed in relation to baseline values. Posttraining myofibrillar synthesis was determined on the day after the final training session. There was not a significant change in fractional myofibrillar synthesis in either the young or the old group after training, and the rate in the older group remained 27% slower (P < 0.05). Whole body protein turnover increased approximately 10% only in the younger group, and 24-h urinary 3-methylhistidine excretion (an index of myofibrillar proteolysis) was not significantly affected by training. These data suggest that the slower myofibrillar synthesis rate in older subjects cannot be explained by disuse.

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