scholarly journals Measurement of the protein-synthetic activity in vivo of various tissues in rats by using [3H]Puromycin

1979 ◽  
Vol 184 (3) ◽  
pp. 663-668 ◽  
Author(s):  
K Nakano ◽  
H Hara
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Relative Rate ◽  
Chain Elongation ◽  
Synthetic Activity ◽  
Tissue Protein Synthesis ◽  
A New Technique ◽  
Protein Free Diet

The validity of a new technique was examined for estimating the protein-synthetic activity of various tissues in vivo. The basic assumption underlying the method is that the number of peptide chains growing on each active ribosome would increase as the protein-synthetic activity of each tissue increases. The principle of the procedure, which was devised originally by Wool & Kurihara [(1967) Proc. Natl. Acad. Sci. U.S.A. 58, 2401-2407] to determine in vitro the number of functional ribosomes in skeletal muscle, is as follows. Puromycin is known to bind easily to the C-terminal end of the growing peptide on ribosomes and thus stop further chain elongation. Hence, if the number of puromycin molecules attached to the nascent peptide is determined by using radioactive puromycin as a tracer, one can estimate the number of growing peptides, i.e. the activity of tissue protein synthesis. By using this technique, it is shown that both starvation and the feeding of a protein-free diet caused marked decreases in the relative rate of formation of peptidyl-puromycin, i.e. activity of protein synthesis in liver, skeletal muscle, heart, spleen, testis, lung, kidney and intestine.

scholarly journals SPECIFIC PROTEIN SYNTHESIS IN CELLULAR DIFFERENTIATION

1972 ◽  
Vol 55 (3) ◽  
pp. 653-680 ◽  
Author(s):  
M. Paul ◽  
M. R. Goldsmith ◽  
J. R. Hunsley ◽  
F. C. Kafatos
Keyword(s):  
Protein Synthesis ◽  
Messenger Rna ◽  
Developmental Stages ◽  
Specific Protein ◽  
Chain Elongation ◽  
Synthetic Activity ◽  
Translational Efficiency ◽  
Kinetics Of

Silkmoth follicles, arranged in a precise developmental sequence within the ovariole, yield pure and uniform populations of follicular epithelial cells highly differentiated for synthesis of the proteinaceous eggshell (chorion). These cells can be maintained and labeled efficiently in organ culture; their in vitro (and cell free) protein synthetic activity reflects their activity in vivo. During differentiation the cells undergo dramatic changes in protein synthesis. For 2 days the cells are devoted almost exclusively to production of distinctive chorion proteins of low molecular weight and of unusual amino acid composition. Each protein has its own characteristic developmental kinetics of synthesis. Each is synthesized as a separate polypeptide, apparently on monocistronic messenger RNA (mRNA), and thus reflects the expression of a distinct gene. The rapid changes in this tissue do not result from corresponding changes in translational efficiency. Thus, the peptide chain elongation rate is comparable for chorion and for proteins synthesized at earlier developmental stages (1.3–1.9 amino acids/sec); moreover, the spacing of ribosomes on chorion mRNA (30–37 codons per ribosome) is similar to that encountered in other eukaryotic systems.

scholarly journals Effects of potassium deficiency on growth and protein synthesis in skeletal muscle and the heart of rats

1989 ◽  
Vol 62 (2) ◽  
pp. 269-284 ◽  
Author(s):  
Inge Dôrup ◽  
Torben Clausen
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Control Level ◽  
Inhibitory Effect ◽  
Potassium Deficiency ◽  
Skeletal Muscle Protein ◽  
K Deficiency

The effects of potassium deficiency on growth, K content and protein synthesis have been compared in 4–13-week-old rats. When maintained on K-deficient fodder (1 mmol/kg) rats ceased to grow within a few days, and the incorporation of [3H]leucine into skeletal muscle protein in vivo was reduced by 28–38%. Pair-feeding experiments showed that this inhibition was not due to reduced energy intake. Following 14 d on K-deficient fodder, there was a further reduction (39–56 %) in the incorporation of [3H]leucine into skeletal muscle protein, whereas the incorporation into plasma, heart and liver proteins was not affected. The accumulation of the non-metabolized amino acid α-aminoisobutyric acid in the heart and skeletal muscles was not reduced. The inhibitory effect of K deficiency on 3H-labelling of muscle protein was seen following intraperitoneal (10–240 min) as well as intravenous (10 min) injection of [3H]leucine. In addition, the incorporation of [3H]phenylalanine into skeletal muscle protein was reduced in K-depleted animals. Following acute K repletion in vivo leading to complete normalization of muscle K content, the incorporation of [3H]leucine into muscle protein showed no increase within 2 h, but reached 76 and 104% of the control level within 24 and 72 h respectively. This was associated with a rapid initial weight gain, but normal body-weight was not reached until after 7 weeks of K repletion. Following 7 d on K-deficient fodder the inhibition of growth and protein synthesis was closely correlated with the K content of the fodder (1–40 mmol/kg) and significant already at modest reductions in muscle K content. In vitro experiments with soleus muscle showed a linear relationship between the incorporation of [3H]leucine into muscle protein and K content, but the sensitivity to cellular K deficiency induced in vitro was much less pronounced than that induced in vivo. Thus, in soleus and extensor digitorum longus (EDL) muscles prepared from K-deficient rats, the incorporation of [3H]leucine was reduced by 30 and 47 % respectively. This defect was completely restored by 24 h K repletion in vivo. It is concluded that in the intact organism protein synthesis and growth are very sensitive to dietary K deficiency and that this can only partly be accounted for by the reduction in cellular K content per se. The observations emphasize the need for adequate K supplies to ensure optimum utilization of food elements for protein synthesis and growth.

Glucocorticoid-induced skeletal muscle atrophy in vitro is attenuated by mechanical stimulation

1992 ◽  
Vol 262 (6) ◽  
pp. C1471-C1477 ◽  
Author(s):  
J. A. Chromiak ◽  
H. H. Vandenburgh
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Content ◽  
Total Protein ◽  
Weight Lifting ◽  
Mechanical Activity ◽  
Synthesis Rate ◽  
Protein Synthesis Rate

Glucocorticoids induce rapid atrophy of fast skeletal myofibers in vivo, and either weight lifting or endurance exercise reduces this atrophy by unknown mechanisms. We examined the effects of the synthetic glucocorticoid dexamethasone (Dex) on protein turnover in tissue-cultured avian fast skeletal myofibers and determined whether repetitive mechanical stretch altered the myofiber response to Dex. In static cultures after 3-5 days, 10(-8) M Dex decreased total protein content 42-74%, total protein synthesis rates 38-56%, mean myofiber diameter 35%, myosin heavy chain (MHC) content 86%, MHC synthesis rate 44%, and fibronectin synthesis rate 29%. Repetitive 10% stretch-relaxations of the cultured myofibers for 60 s every 5 min for 3-4 days prevented 52% of the Dex-induced decrease in protein content, 42% of the decrease in total protein synthesis rate, 77% of the decrease in MHC content, 42% of the decrease in MHC synthesis rate, and 67% of the decrease in fibronectin synthesis rate. This in vitro model system will complement in vivo studies in understanding the mechanism by which mechanical activity and glucocorticoids interact to regulate skeletal muscle growth.

Skeletal muscle, liver and wool protein synthesis by sheep infected by the nematode Trichostrongylus colubriformis

1975 ◽  
Vol 26 (6) ◽  
pp. 1063
Author(s):  
LEA Symons ◽  
WO Jones
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Liver Protein ◽  
Trichostrongylus Colubriformis ◽  
Intestinal Nematode ◽  
Skeletal Muscle Proteins

Incorporation of radioisotopically labelled L-leucine into skeletal muscle proteins was measured in vivo and in vitro, and into liver proteins in vivo in three groups of sheep: (1) infected by Trichostrongylus colubriformis, (2) uninfected, pair-fed with the infected animals, (3) uninfected, fed ad lib. Incorporation of [14C]L-leucine by an homogenate of wool follicles from infected and uninfected sheep was also measured. Incorporation of leucine by muscle, and hence muscle protein synthesis, was equally depressed in the anorexic infected sheep losing weight, and in pair-fed animals, whether measured in vivo or in vitro, or expressed in terms of either RNA or DNA. Incorporation into protein was elevated equally in vivo in the livers of the infected and pair-fed sheep when expressed in terms of content of tissue nitrogen, but not in terms of cither nucleic acid. Incorporation by the wool follicular homogenate was appreciably depressed by the infection and is consistent with the poor wool growth in nematode infections. These results show that the same depression of skeletal muscle and, possibly, elevation of liver protein synthesis occur in a ruminant as were reported earlier for laboratory monogastric animals with intestinal nematode infections. Pair-feeding uninfected animals in both this and the earlier experiments emphasized the importance of anorexia as a major cause of these effects on protein synthesis. The importance of these effects upon production is discussed briefly.

Anaesthetic Agents and Their Effect on Tissue Protein Synthesis in the Rat

1989 ◽  
Vol 77 (6) ◽  
pp. 651-655 ◽  
Author(s):  
S. D. Heys ◽  
A. C. Norton ◽  
C. R. Dundas ◽  
O. Eremin ◽  
K. Ferguson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Young Male ◽  
Male Rats ◽  
Liver Protein ◽  
Arterial Blood Gas ◽  
Anaesthetic Agents ◽  
Arterial Blood ◽  
Tissue Protein Synthesis

1. Rates of protein synthesis were measured, in vivo, in lung, liver, heart and skeletal muscle of young male rats. Groups of rats were exposed for 1 h duration to one of the following anaesthetic regimens: 1.4% halothane, 2.2% halothane, 1.4% halothane in 66% nitrous oxide, intravenous pentobarbitone (20 mg/kg) and intravenous midazolam (18 mg/kg) combined with fentanyl (2 μg/kg). Fractional rates of protein synthesis were determined by injecting [3H]phenylalanine (150 μmol/100 g body weight) 2. Liver protein synthesis was depressed significantly by all regimens, except midazolam/fentanyl, by up to 37.7% of control values. Lung protein synthesis was significantly reduced by all the anaesthetic agents by up to 30% of control rates 3. The effects of the anaesthetic agents on skeletal muscle and heart were small and not statistically significant 4. There was no evidence of ventilatory depression as manifested by changes in arterial blood gas partial pressures of CO2 and O2, except in the group treated with 2.2% halothane.

The effect of caffeine on skeletal muscle anabolic signaling and hypertrophy

2017 ◽  
Vol 42 (6) ◽  
pp. 621-629 ◽  
Author(s):  
Timothy M. Moore ◽  
Xavier M. Mortensen ◽  
Conrad K. Ashby ◽  
Alexander M. Harris ◽  
Karson J. Kump ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Growth ◽  
Mtor Signaling ◽  
Signaling Proteins ◽  
Signaling Protein ◽  
Before And After ◽  
Amp Activated Protein Kinase

Caffeine is a widely consumed stimulant with the potential to enhance physical performance through multiple mechanisms. However, recent in vitro findings have suggested that caffeine may block skeletal muscle anabolic signaling through AMP-activated protein kinase (AMPK)-mediated inhibition of mechanistic target of rapamycin (mTOR) signaling pathway. This could negatively affect protein synthesis and the capacity for muscle growth. The primary purpose of this study was to assess the effect of caffeine on in vivo AMPK and mTOR pathway signaling, protein synthesis, and muscle growth. In cultured C2C12 muscle cells, physiological levels of caffeine failed to impact mTOR activation or myoblast proliferation or differentiation. We found that caffeine administration to mice did not significantly enhance the phosphorylation of AMPK or inhibit signaling proteins downstream of mTOR (p70S6k, S6, or 4EBP1) or protein synthesis after a bout of electrically stimulated contractions. Skeletal muscle-specific knockout of LKB1, the primary AMPK activator in skeletal muscle, on the other hand, eliminated AMPK activation by contractions and enhanced S6k, S6, and 4EBP1 activation before and after contractions. In rats, the addition of caffeine did not affect plantaris hypertrophy induced by the tenotomy of the gastrocnemius and soleus muscles. In conclusion, caffeine administration does not impair skeletal muscle load-induced mTOR signaling, protein synthesis, or muscle hypertrophy.

Corrigendum - Skeletal muscle, liver and wool protein synthesis by sheep infected by the nematode Trichostrongylus colubriformis

1975 ◽  
Vol 26 (6) ◽  
pp. 1063
Author(s):  
LEA Symons ◽  
WO Jones
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Liver Protein ◽  
Trichostrongylus Colubriformis ◽  
Intestinal Nematode ◽  
Skeletal Muscle Proteins

Incorporation of radioisotopically labelled L-leucine into skeletal muscle proteins was measured in vivo and in vitro, and into liver proteins in vivo in three groups of sheep: (1) infected by Trichostrongylus colubriformis, (2) uninfected, pair-fed with the infected animals, (3) uninfected, fed ad lib. Incorporation of [14C]L-leucine by an homogenate of wool follicles from infected and uninfected sheep was also measured. Incorporation of leucine by muscle, and hence muscle protein synthesis, was equally depressed in the anorexic infected sheep losing weight, and in pair-fed animals, whether measured in vivo or in vitro, or expressed in terms of either RNA or DNA. Incorporation into protein was elevated equally in vivo in the livers of the infected and pair-fed sheep when expressed in terms of content of tissue nitrogen, but not in terms of cither nucleic acid. Incorporation by the wool follicular homogenate was appreciably depressed by the infection and is consistent with the poor wool growth in nematode infections. These results show that the same depression of skeletal muscle and, possibly, elevation of liver protein synthesis occur in a ruminant as were reported earlier for laboratory monogastric animals with intestinal nematode infections. Pair-feeding uninfected animals in both this and the earlier experiments emphasized the importance of anorexia as a major cause of these effects on protein synthesis. The importance of these effects upon production is discussed briefly.

Protein synthesis in liver, skeletal muscle, and brown adipose tissue of rats fed a protein-deficient diet

1983 ◽  
Vol 3 (6) ◽  
pp. 569-575 ◽  
Author(s):  
P. W. Emery ◽  
N. J. Rothwell ◽  
M. J. Stock
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Protein Content ◽  
Deficient Diet ◽  
Rna Content ◽  
Brown Adipose ◽  
Tissue Protein Synthesis

Feeding protein-deficient diets to rats is known to stimulate diet-induced thermogenesis and activate brown adipose tissue (BAT). The fact that BAT protein content, unlike that of other tissues, is unnaffected by protein deficiency prompted us to measure tissue protein synthesis in vivo in animals maintained on normal- (18.8%) and low- (7.6%) protein (LP) diets. Protein synthesis was depressed in the liver of the LP rats due to a fall in RNA activity, with no change in RNA content, and synthesis was also reduced in skeletal muscle from the LP group, but this was due to decreased RNA content with no change in RNA activity. Conversely, protein synthesis, RNA, DNA, and protein content of interscapular BAT were all unaltered in protein-restricted animals. These data indicate that, unlike liver, skeletal muscle, and whole carcass, BAT protein synthesis is not reduced in protein-restricted rats, and this may be related to activation of thermo-genesis in the tissue.

scholarly journals Roles of creatine in the regulation of cardiac protein synthesis

1976 ◽  
Vol 68 (1) ◽  
pp. 159-163 ◽  
Author(s):  
JS Ingwall ◽  
K Wildenthal
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Specific Effect ◽  
Muscular Activity ◽  
Creatine Phosphate ◽  
Contractile Protein ◽  
Physiological Mechanisms ◽  
Intracellular Compartments

The observation that increased muscular activity leads to muscle hypertrophy is well known, but identification of the biochemical and physiological mechanisms by which this occurs remains an important problem. Experiments have been described (5, 6) which suggest that creatine, an end product of contraction, is involved in the control of contractile protein synthesis in differentiating skeletal muscle cells and may be the chemical signal coupling increased muscular activity and the increased muscular mass. During contraction, the creatine concentration in muscle transiently increases as creatine phosphate is hydrolyzed to regenerate ATP. In isometric contraction in skeletal muscle for example, Edwards and colleagues (3) have found that nearly all of the creatine phosphate is hydrolyzed. In this case, the creatine concentration is increased about twofold, and it is this transient change in creatine concentration which is postulated to lead to increased contractile protein synthesis. If creatine is found in several intracellular compartments, as suggested by Lee and Vissher (7), local changes in concentration may be greater then twofold. A specific effect on contractile protein synthesis seems reasonable in light of the work of Rabinowitz (13) and of Page et al. (11), among others, showing disproportionate accumulation of myofibrillar and mitochondrial proteins in response to work-induced hypertrophy and thyroxin-stimulated growth. Previous experiments (5, 6) have shown that skeletal muscles cells which have differentiated in vitro or in vivo synthesize myosin heavy-chain and actin, the major myofibrillar polypeptides, faster when supplied creatine in vitro. The stimulation is specific for contractile protein synthesis since neither the rate of myosin turnover nor the rates of synthesis of noncontractile protein and DNA are affected by creatine. The experiments reported in this communication were undertaken to test whether creatine selectively stimulates contractile protein synthesis in heart as it does in skeletal muscle.

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