scholarly journals Insulin fails to enhance mTOR phosphorylation, mitochondrial protein synthesis, and ATP production in human skeletal muscle without amino acid replacement

2012 ◽  
Vol 303 (9) ◽  
pp. E1117-E1125 ◽  
Author(s):  
Rocco Barazzoni ◽  
Kevin R. Short ◽  
Yan Asmann ◽  
Jill M. Coenen-Schimke ◽  
Matthew M. Robinson ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Enzyme Activities ◽  
Muscle Protein ◽  
Mitochondrial Protein ◽  
Mitochondrial Genes ◽  
Mrna Levels ◽  
Mitochondrial Enzyme ◽  
Mitochondrial Protein Synthesis ◽  
Atp Production

Systemic insulin administration causes hypoaminoacidemia by inhibiting protein degradation, which may in turn inhibit muscle protein synthesis (PS). Insulin enhances muscle mitochondrial PS and ATP production when hypoaminoacidemia is prevented by exogenous amino acid (AA) replacement. We determined whether insulin would stimulate mitochondrial PS and ATP production in the absence of AA replacement. Using l-[1,2-13C]leucine as a tracer, we measured the fractional synthetic rate of mitochondrial as well as sarcoplasmic and mixed muscle proteins in 18 participants during sustained (7-h) insulin or saline infusion ( n = 9 each). We also measured muscle ATP production, mitochondrial enzyme activities, mRNA levels of mitochondrial genes, and phosphorylation of signaling proteins regulating protein synthesis. The concentration of circulating essential AA decreased during insulin infusion. Mitochondrial, sarcoplasmic, and mixed muscle PS rates were also lower during insulin (2–7 h) than during saline infusions despite increased mRNA levels of selected mitochondrial genes. Under these conditions, insulin did not alter mitochondrial enzyme activities and ATP production. These effects were associated with enhanced phosphorylation of Akt but not of protein synthesis activators mTOR, p70S6K, and 4EBP1. In conclusion, sustained physiological hyperinsulinemia without AA replacement did not stimulate PS of mixed muscle or protein subfractions and did not alter muscle mitochondrial ATP production in healthy humans. These results support that insulin and AA act in conjunction to stimulate muscle mitochondrial function and mitochondrial protein synthesis.

Growth hormone decreases muscle glutamine production and stimulates protein synthesis in hypercatabolic patients

2000 ◽  
Vol 279 (2) ◽  
pp. E323-E332 ◽  
Author(s):  
Gianni Biolo ◽  
Fulvio Iscra ◽  
Alessandra Bosutti ◽  
Gabriele Toigo ◽  
Beniamino Ciocchi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Protein Synthesis ◽  
Amino Acid ◽  
De Novo ◽  
Muscle Protein ◽  
Recombinant Human Growth Hormone ◽  
Glutamine Metabolism ◽  
Trauma Patients ◽  
Mrna Levels ◽  
Glutamine Production

We determined the effects of 24-h recombinant human growth hormone (rhGH) infusion into a femoral artery on leg muscle protein kinetics, amino acid transport, and glutamine metabolism in eight adult hypercatabolic trauma patients. Metabolic pathways were assessed by leg arteriovenous catheterization and muscle biopsies with the use of stable amino acid isotopes. Muscle mRNA levels of selected enzymes were determined by competitive PCR. rhGH infusion significantly accelerated the inward transport rates of phenylalanine and leucine and protein synthesis, whereas the muscle protein degradation rate and cathepsin B and UbB polyubiquitin mRNA levels were not significantly modified by rhGH. rhGH infusion decreased the rate of glutamine de novo synthesis and glutamine precursor availability, total branched-chain amino acid catabolism, and nonprotein glutamate utilization. Thus net glutamine release from muscle into circulation significantly decreased after rhGH administration (∼50%), whereas glutamine synthetase mRNA levels increased after rhGH infusion, possibly to compensate for reduced glutamine precursor availability. We conclude that, after trauma, the anticatabolic action of rhGH is associated with a potentially harmful decrease in muscle glutamine production.

The effect of chloramphenicol, ethidium bromide and cycloheximide on mortality and mitochondrial protein synthesis of adult blowflies

1980 ◽  
Vol 41 (1) ◽  
pp. 273-289
Author(s):  
B. Ashour ◽  
M. Tribe ◽  
P. Whittaker
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Drug Treatment ◽  
Ethidium Bromide ◽  
Flight Muscle ◽  
Mitochondrial Protein ◽  
Age Groups ◽  
Age Group ◽  
Mitochondrial Protein Synthesis ◽  
Inhibition Of Protein Synthesis

The effects of cycloheximide, chloramphenicol and ethidium bromide on the blowfly Calliphora erythrocephala were studied. In the first set of experiments, toxic levels were determined by examining activity and mortality of flies after injection of various doses of each drug. In the second set of experiments, the effect of drug treatment on flight muscle mitochondrial protein synthesis was determined in relation to age by following the incorporation of radioactively labelled amino acid, [3H]leucine, into mitochondrial protein in vivo. To confirm the developmental changes in flight muscle mitochondria, mitochondrial protein content per fly was estimated from emergence to 30 days of age; the highest protein level was recorded between 6 and 10 days of age. Maximum incorporation of labelled amino acid was found in newly emerged flies, and this age group was also the most sensitive to drug treatment. By the time flies had reached 6–10 days of age, amino acid incorporation had declined to about two-thirds of the rate obtained with newly emerged flies. With 6–10-day old flies, however, the highest value for flight muscle mitochondrial protein per fly was recorded, and these flies also displayed the greatest resistance to drug treatment of any age group investigated. For example, inhibition of protein synthesis following injection of 300 micrograms/fly of chloramphenicol was only about 15% below the untreated control in 6–10-day-old flies, whereas in all other age groups investigated, inhibition ranged between 30 and 50% of the controls. At 15–20 days of age, protein synthesis decreased to a third of the newly emerged flies' rate and continued to decrease further in the 30–35-day-old group, where it was less than one sixth of the youngest age group. The effect of drug treatment on these older flies was also less than that observed with newly emerged flies, especially after chloramphenicol and ethidium bromide injections. The effect of cycloheximide however, was much the same in all age groups, with inhibition of protein synthesis being 80–90% of controls. Surprisingly, cycloheximide (1–10 micrograms/fly) had little initial effect on mortality of young flies, despite almost complete blockage in the synthesis of mitochondrial proteins at these concentrations. 95% mortality occurred only when doses of 20 micrograms/fly were given. In contrast, high doses of chloramphenicol (400 micrograms/fly) and ethidium bromide (15 micrograms/fly) caused almost total mortality a few hours after injection, although such doses never induced more than about 50% inhibition of mitochondrial protein synthesis. Each drug therefore has a different site of inhibition and induces different mortality effects. Possible explanations for these differences in mortality are discussed.

Human muscle protein synthesis and breakdown during and after exercise

2009 ◽  
Vol 106 (6) ◽  
pp. 2026-2039 ◽  
Author(s):  
Vinod Kumar ◽  
Philip Atherton ◽  
Kenneth Smith ◽  
Michael J. Rennie
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Turnover ◽  
Acute Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mitochondrial Protein ◽  
Human Muscle ◽  
Muscle Protein Turnover ◽  
Amino Acid Availability

Skeletal muscle demonstrates extraordinary mutability in its responses to exercise of different modes, intensity, and duration, which must involve alterations of muscle protein turnover, both acutely and chronically. Here, we bring together information on the alterations in the rates of synthesis and degradation of human muscle protein by different types of exercise and the influences of nutrition, age, and sexual dimorphism. Where possible, we summarize the likely changes in activity of signaling proteins associated with control of protein turnover. Exercise of both the resistance and nonresistance types appears to depress muscle protein synthesis (MPS), whereas muscle protein breakdown (MPB) probably remains unchanged during exercise. However, both MPS and MPB are elevated after exercise in the fasted state, when net muscle protein balance remains negative. Positive net balance is achieved only when amino acid availability is increased, thereby raising MPS markedly. However, postexercise-increased amino acid availability is less important for inhibiting MPB than insulin, the secretion of which is stimulated most by glucose availability, without itself stimulating MPS. Exercise training appears to increase basal muscle protein turnover, with differential responses of the myofibrillar and mitochondrial protein fractions to acute exercise in the trained state. Aging reduces the responses of myofibrillar protein and anabolic signaling to resistance exercise. There appear to be few, if any, differences in the response of young women and young men to acute exercise, although there are indications that, in older women, the responses may be blunted more than in older men.

THYROXINE STIMULATION OF AMINO ACID INCORPORATION INTO MITOCHONDRIAL PROTEIN: DIFFERENCES BETWEEN IN VIVO AND IN VITRO EFFECTS

1973 ◽  
Vol 72 (4) ◽  
pp. 684-696 ◽  
Author(s):  
Amirav Gordon ◽  
Martin I. Surks ◽  
Jack H. Oppenheimer
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Mitochondrial Protein ◽  
Leucine Incorporation ◽  
Mitochondrial Protein Synthesis ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Stimulation Of

ABSTRACT The in vivo and in vitro stimulation of rat hepatic mitochondrial protein synthesis by thyroxine (T4) was compared. In confirmation of Buchanan & Tapley (1966). T4 added to isolated mitochondria rapidly stimulated [14C] leucine incorporation into mitochondrial protein. The in vitro stimulation was reversed after T4 was removed by incubating the mitochondria with bovine serum albumin (BSA). The decrease in T4 stimulation of protein synthesis appeared proportional to the T4 removed by BSA. Thus, it appears probable that exchangeable T4 controls the in vitro system. In contrast, the increase in mitochondrial protein synthesis which was observed 3 to 4 days after pretreatment of hypothyroid rats with labelled and non-radioactive T4 was not reversed by BSA treatment. Moreover, mitochondrial radioactivity could not be extracted with albumin. The in vivo phenomenon does not, therefore, appear to be related to exchangeable hormone in the mitochondria. Furthermore, the estimated quantity of T4 associated with mitochondria after in vivo stimulation was at least two orders of magnitude less than that required to produce comparable stimulation of mitochondrial protein synthesis in vitro. These findings strongly suggest that in vitro and in vivo stimulation of amino acid incorporation by T4 may be mediated by different biochemical mechanisms.

scholarly journals Endurance-Type Exercise Increases Bulk and Individual Mitochondrial Protein Synthesis Rates in Rats

2020 ◽  
Vol 30 (2) ◽  
pp. 153-164 ◽  
Author(s):  
Andrew M. Holwerda ◽  
Freek G. Bouwman ◽  
Miranda Nabben ◽  
Ping Wang ◽  
Janneau van Kranenburg ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Atp Synthase ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mitochondrial Protein ◽  
Experimental Period ◽  
Mitochondrial Protein Synthesis ◽  
The Impact

Physical activity increases muscle protein synthesis rates. However, the impact of exercise on the coordinated up- and/or downregulation of individual protein synthesis rates in skeletal muscle tissue remains unclear. The authors assessed the impact of exercise on mixed muscle, myofibrillar, and mitochondrial protein synthesis rates as well as individual protein synthesis rates in vivo in rats. Adult Lewis rats either remained sedentary (n = 3) or had access to a running wheel (n = 3) for the last 2 weeks of a 3-week experimental period. Deuterated water was injected and subsequently administered in drinking water over the experimental period. Blood and soleus muscle were collected and used to assess bulk mixed muscle, myofibrillar, and mitochondrial protein synthesis rates using gas chromatography–mass spectrometry and individual muscle protein synthesis rates using liquid chromatography–mass spectrometry (i.e., dynamic proteomic profiling). Wheel running resulted in greater myofibrillar (3.94 ± 0.26 vs. 3.03 ± 0.15%/day; p < .01) and mitochondrial (4.64 ± 0.24 vs. 3.97 ± 0.26%/day; p < .05), but not mixed muscle (2.64 ± 0.96 vs. 2.38 ± 0.62%/day; p = .71) protein synthesis rates, when compared with the sedentary condition. Exercise impacted the synthesis rates of 80 proteins, with the difference from the sedentary condition ranging between −64% and +420%. Significantly greater synthesis rates were detected for F1-ATP synthase, ATP synthase subunit alpha, hemoglobin, myosin light chain-6, and synaptopodin-2 (p < .05). The skeletal muscle protein adaptive response to endurance-type exercise involves upregulation of mitochondrial protein synthesis rates, but it is highly coordinated as reflected by the up- and downregulation of various individual proteins across different bulk subcellular protein fractions.

scholarly journals Assessment of protein synthesis in highly aerobic canine species at the onset and during exercise training

2015 ◽  
Vol 118 (7) ◽  
pp. 811-817 ◽  
Author(s):  
Benjamin F. Miller ◽  
Sarah E. Ehrlicher ◽  
Joshua C. Drake ◽  
Frederick F. Peelor ◽  
Laurie M. Biela ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Exercise Training ◽  
Dna Synthesis ◽  
Aerobic Exercise ◽  
Training Program ◽  
Muscle Protein ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Synthesis ◽  
Exercise Training Program ◽  
Labrador Retrievers

Canis lupus familiaris, the domesticated dog, is capable of extreme endurance performance. The ability to perform sustained aerobic exercise is dependent on a well-developed mitochondrial reticulum. In this study we examined the cumulative muscle protein and DNA synthesis in groups of athletic dogs at the onset of an exercise training program and following a strenuous exercise training program. We hypothesized that both at the onset and during an exercise training program there would be greater mitochondrial protein synthesis rates compared with sedentary control with no difference in mixed or cytoplasmic protein synthesis rates. Protein synthetic rates of three protein fractions and DNA synthesis were determined over 1 wk using 2H2O in competitive Alaskan Huskies and Labrador Retrievers trained for explosive device detection. Both groups of dogs had very high rates of skeletal muscle protein synthesis in the sedentary state [Alaskan Huskies: Mixed = 2.28 ± 0.12, cytoplasmic (Cyto) = 2.91 ± 0.10, and mitochondrial (Mito) = 2.62 ± 0.07; Labrador Retrievers: Mixed = 3.88 ± 0.37, Cyto = 3.85 ± 0.06, and Mito = 2.92 ± 0.20%/day]. Mitochondrial (Mito) protein synthesis rates did not increase at the onset of an exercise training program. Exercise-trained dogs maintained Mito protein synthesis during exercise training when mixed (Mixed) and cytosolic (Cyto) fractions decreased, and this coincided with a decrease in p-RpS6 but also a decrease in p-ACC signaling. Contrary to our hypothesis, canines did not have large increases in mitochondrial protein synthesis at the onset or during an exercise training program. However, dogs have a high rate of protein synthesis compared with humans that perhaps does not necessitate an extra increase in protein synthesis at the onset of aerobic exercise training.

Effects of inhibition of mitochondrial protein synthesis in skeletal muscle

1987 ◽  
Vol 253 (6) ◽  
pp. C866-C871 ◽  
Author(s):  
R. S. Williams ◽  
W. Harlan
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Adaptive Response ◽  
Citrate Synthase ◽  
Contractile Activity ◽  
Mitochondrial Protein ◽  
Mitochondrial Genes ◽  
Mitochondrial Protein Synthesis ◽  
Inhibit Activity ◽  
Genes Encoding

To evaluate the participation of proteins derived from mitochondrial genes in the adaptive response of skeletal muscle to increased contractile activity, we administered chloramphenicol (CAP; 200-1,000 mg.kg-1.day-1), an inhibitor of translation from mitochondrial ribosomes, to adult rabbits undergoing electrical stimulation of the tibialis anterior muscle of one hind limb. In unmedicated animals, 10 days of electrical stimulation increased maximum velocity (Vmax) of cytochrome oxidase and citrate synthase by 214 +/- 17 and 201 +/- 16% (P less than 0.01). In a dose-dependent manner, CAP abolished activity-induced increases in cytochrome oxidase Vmax, suggesting that augmented mitochondrial protein synthesis is necessary for the adaptive response of enzymes that require protein subunits encoded by mitochondrial genes. However, CAP failed to inhibit activity-induced changes in Vmax of enzymes derived exclusively from nuclear genes (citrate synthase and aldolase). CAP also failed to inhibit activity-induced increases in mRNA transcribed from the nuclear genes encoding beta-F1 ATPase or myoglobin, or from the mitochondrial genes encoding 12S rRNA, 16S rRNA, or cytochrome b. These latter findings suggest that mitochondrial translation products do not participate in pretranslational regulation of these nuclear or mitochondrial genes in response to changes in contractile activity of skeletal muscle.

scholarly journals Dietary amylose/amylopectin ratio influences the expression of amino acid transporters and enzyme activities for amino acid metabolism in the gastrointestinal tract of goats

2021 ◽  
pp. 1-31
Author(s):  
Xiaokang Lv ◽  
Chuanshe Zhou ◽  
Tao Ran ◽  
Jinzhen Jiao ◽  
Yong Liu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Transporters ◽  
Mrna Levels ◽  
Ileal Mucosa ◽  
Dietary Starch ◽  
High Amylose

Abstract This study was designed to investigate the effects of dietary starch structure on muscle protein synthesis and gastrointestinal amino acid (AA) transport and metabolism of goats. Twenty-seven Xiangdong black female goats (average body weight = 9.00 ± 1.12 kg) were randomly assigned to three treatments, i.e., fed a T1 (normal corn 100%, high amylose corn 0%), T2 (normal corn 50%, high amylose corn 50%) and T3 (normal corn 0%, high amylose corn 100%) diet for 35 days, respectively. All amino acids in the ileal mucosa were decreased linearly as amylose/amylopectin increased in diets (P<0.05). The plasma valine (linear, P=0.03), leucine (linear, P=0.04), and total amino acids content (linear, P=0.03) increased linearly with the increase in the ratio of amylose in the diet. The relative mRNA levels of SLC38A1 (linear, P=0.01), SLC3A2 (linear, P=0.02), and SLC38A9 (linear, P=0.02) in the ileum increased linearly with the increase in the ratio of amylose in the diet. With the increase in the ratio of amylose/amylopectin in the diet, the mRNA levels of ACADSB (linear, P=0.04), BCAT1 (linear, P=0.02), and BCKDHB (linear, P=0.01) in the ileum decreased linearly. Our results revealed that the protein abundances of p-mTOR (P<0.001), p-4EBP1 (P<0.001), and p-S6K1 (P<0.001) of T2 and T3 were significantly higher than that of T1. In general, a diet with a high amylose ratio could reduce the consumption of amino acids in the intestine, allowing more amino acids to enter the blood to maintain higher muscle protein synthesis through the mTOR pathway.

scholarly journals Lack of Increase in Muscle Mitochondrial Protein Synthesis During the Course of Aerobic Exercise and Its Recovery in the Fasting State Irrespective of Obesity

2021 ◽  
Vol 12 ◽  
Author(s):  
Nathan Serrano ◽  
Lee Tran ◽  
Nyssa Hoffman ◽  
Lori Roust ◽  
Elena A. De Filippis ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Aerobic Exercise ◽  
Body Fat ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mitochondrial Protein ◽  
Fasting State ◽  
Mitochondrial Protein Synthesis ◽  
Post Exercise

Acute aerobic exercise induces skeletal muscle mitochondrial gene expression, which in turn can increase muscle mitochondrial protein synthesis. In this regard, the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), is a master regulator of mitochondrial biogenesis, and thus mitochondrial protein synthesis. However, PGC-1α expression is impaired in muscle of humans with obesity in response to acute aerobic exercise. Therefore, we sought to determine whether muscle mitochondrial protein synthesis is also impaired under the same conditions in humans with obesity. To this end, we measured mitochondrial and mixed-muscle protein synthesis in skeletal muscle of untrained subjects with (body fat: 34.7 ± 2.3%) and without (body fat: 25.3 ± 3.3%) obesity in a basal period and during a continuous period that included a 45 min cycling exercise (performed at an intensity corresponding to 65% of heart rate reserve) and a 3-h post-exercise recovery. Exercise increased PGC-1α mRNA expression in muscle of subjects without obesity, but not in subjects with obesity. However, muscle mitochondrial protein synthesis did not increase in either subject group. Similarly, mixed-muscle protein synthesis did not increase in either group. Concentrations of plasma amino acids decreased post-exercise in the subjects without obesity, but not in the subjects with obesity. We conclude that neither mitochondrial nor mixed-muscle protein synthesis increase in muscle of humans during the course of a session of aerobic exercise and its recovery period in the fasting state irrespective of obesity.Trial Registration: The study has been registered within ClinicalTrials.gov (NCT01824173).

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