Protein turnover—what does it mean for animal production?

2003 ◽  
Vol 83 (3) ◽  
pp. 327-340 ◽  
Author(s):  
G. E. Lobley
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Intestinal Tract ◽  
Essential Amino Acids ◽  
Animal Products ◽  
Peripheral Tissues ◽  
Vital Functions ◽  
Gastro Intestinal Tract ◽  
Synthesis And Degradation

The dynamics of protein turnover confer great advantages for homeothermy, plasticity and metabolic function in mammals. The different roles played by the various organs have led to aspects of protein synthesis and degradation that aid the various functions performed. The so-called “non-productive” organs such as the gastro-intestinal tract and liver produce large quantities of export proteins that perform vital functions. Not all these proteins are recovered, however, and thus function can result in lowered net conversion of plant protein to animal products. The splanchnic tissues also oxidize essential amino acids (AA). For example, the gut catabolizes leucine, lysine and methionine, but not threonine and phenylalanine, as part of a complex interaction between AA supply and tissue metabolic activity. Losses by oxidation and endogenous secretions can markedly alter the pattern of absorbed AA. The fractional rates of extraction of total AA inflow to the liver are low and this allows short-term flexibility in controlling supply to peripheral tissues. Recent evidence suggests that the role of the liver in AA catabolism is more a response to non-use by other tissues rather than an immediate regulation of supply to the periphery. Neither arterial supply of AA nor the rate of transport into peripheral tissues limits protein gain, except when supply is very limited. Rather, control is probably exerted via hormone-nutrient interactions. Key words: Protein synthesis, amino acid, gastro-intestinal tract, liver, muscle, mammary gland

scholarly journals Effects of Growth Hormone on Leptin Metabolism and Energy Expenditure in Hemodialysis Patients with Protein-Calorie Malnutrition

2000 ◽  
Vol 11 (11) ◽  
pp. 2106-2113
Author(s):  
GIACOMO GARIBOTTO ◽  
ANTONINA BARRECA ◽  
ANTONELLA SOFIA ◽  
RODOLFO RUSSO ◽  
FULVIO FIORINI ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Protein Synthesis ◽  
Energy Expenditure ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Resting Energy Expenditure ◽  
Hemodialysis Patients ◽  
Gh Treatment ◽  
Peripheral Tissues

Abstract. The relationships among growth hormone (GH), leptin, and resting energy expenditure (REE) are not understood. It has been reported that in malnourished hemodialysis patients, GH increases muscle protein synthesis, a process that requires energy. The present study evaluated the arterial levels and the forearm exchange of leptin, as well as the REE of the same patients during their participation in the same study, in four sequential 6-wk periods: I, baseline; II, GH treatment; III, washout; and IV, GH + intradialytic parenteral nutrition. During periods II and IV, patients received GH (5 mg three times per week). REE rose by 5% in period II, declined during period III, and rose by 7% during period IV. Basal leptin levels were low (2.0 ± 0.19 ng/L). Insulin and leptin levels, as well as leptin release from the forearm, were unchanged during periods I through III but rose (+ 36%; P < 0.05) during period IV. Changes in arterial leptin were directly related to changes in forearm leptin release (P < 0.002), indicating a role of leptin production by peripheral tissues on leptinemia. Changes in leptin release were directly related to insulin (P < 0.001) and, less consistently, to insulin-like growth factor-binding protein-1 levels (P < 0.02). Similarly, variations in leptin levels were directly related to insulin (P < 0.01). Variations in REE were not related to variations in leptin or insulin levels but to changes in muscle protein synthesis (P < 0.025). The data show that in malnourished hemodialysis patients, treatment with GH is not invariably associated with an increase in leptin production. An increase in leptin release by peripheral tissues and leptin levels occurs only in the setting of hyperinsulinemia. The increase in REE that is induced by treatment with GH is not dependent on changes in leptin but is largely accounted for by the energy cost of the stimulation of muscle protein synthesis.

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.

scholarly journals INTERACTION OF THE SYMBIOTIC MICROBIOTA OF THE GASTRO-INTESTINAL TRACT WITH THE NERVOUS SYSTEM OF THE HOST ORGANISM

2019 ◽  
Vol 1 (2) ◽  
pp. 90-100
Author(s):  
A V Oleskin
Keyword(s):  
Nervous System ◽  
Intestinal Tract ◽  
Distal Part ◽  
Human Organism ◽  
Gi Tract ◽  
Physical And Mental Health ◽  
Gi Symptoms ◽  
Gastro Intestinal Tract ◽  
Symbiotic Microbiota

Symbiotic microorganisms inhabit a wide variety of niches in the human organism. Of paramount importance is the microbiota of the gastro-intestinal (GI) tract, especially of its distal part (the colon). Bidirectional signal exchange proceeds within the microbiota-host system, and diverse microbial metabolites modify the functions of the nervous system via metabolic, genetic, and neuroendocrine pathways. Increasing attention is currently given to the role of the GI microbiota in terms of the host's physical and mental health; therefore, it has been suggested to replace the widely used term gut-brain axis with the new term microbiota-gut-brain axis. The GI microbiota directly interacts with the enteric nervous system (ENS) that represents a partly autonomous subdivision of the nervous system. An important role is also played by the GI tract-innervating vagus nerve. In addition, the influence of the microbiota on the nervous system can be mediated by the immune system. The microbiota impact on the nervous system of the host results in significant alterations in the host's behavior, mood, and even taste. In the literature, there is evidence that neurological and psychological diseases are linked to microecological disorders (dysbioses) in the GI tract. In particular, dysbioses with manifest GI symptoms are often accompanied by serious brain problems.

scholarly journals Proteome dynamics during homeostatic scaling in cultured neurons

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Aline Ricarda Dörrbaum ◽  
Beatriz Alvarez-Castelao ◽  
Belquis Nassim-Assir ◽  
Julian D Langer ◽  
Erin M Schuman
Keyword(s):  
Protein Synthesis ◽  
Protein Function ◽  
Protein Turnover ◽  
Experimental Approach ◽  
Large Fraction ◽  
Synaptic Proteins ◽  
Turnover Rates ◽  
Cellular Environment ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Protein turnover, the net result of protein synthesis and degradation, enables cells to remodel their proteomes in response to internal and external cues. Previously, we analyzed protein turnover rates in cultured brain cells under basal neuronal activity and found that protein turnover is influenced by subcellular localization, protein function, complex association, cell type of origin, and by the cellular environment (Dörrbaum et al., 2018). Here, we advanced our experimental approach to quantify changes in protein synthesis and degradation, as well as the resulting changes in protein turnover or abundance in rat primary hippocampal cultures during homeostatic scaling. Our data demonstrate that a large fraction of the neuronal proteome shows changes in protein synthesis and/or degradation during homeostatic up- and down-scaling. More than half of the quantified synaptic proteins were regulated, including pre- as well as postsynaptic proteins with diverse molecular functions.

Meal stimulation of albumin synthesis: a significant contributor to whole body protein synthesis in humans

1992 ◽  
Vol 263 (4) ◽  
pp. E794-E799 ◽  
Author(s):  
P. De Feo ◽  
F. F. Horber ◽  
M. W. Haymond
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Combined Treatment ◽  
Essential Amino Acids ◽  
Whole Body ◽  
Albumin Synthesis ◽  
Body Protein ◽  
Peripheral Tissues ◽  
Stimulation Of

The present studies were performed to test the hypothesis that the liver, by increasing the synthesis of specific plasma proteins during the absorption of an amino acid meal, may play an important role in the temporary "storage" of ingested essential amino acids and to explore the effects of glucocorticosteroids and recombinant human growth hormone (rhGH) on these processes. The fractional synthetic rates of albumin and fibrinogen were determined using simultaneous infusions of intravenous [1-14C]leucine and intraduodenal [4,5-3H]leucine after 22 h fasting and during absorption of glucose and amino acids in four groups of normal subjects treated for 1 wk with placebo, prednisone (0.8 mg.kg-1.day-1), rhGH (0.1 mg.kg-1.day-1), or combined treatment. When compared with the fasted state and independent of the route of tracer delivery and hormonal treatment, albumin, but not fibrinogen, synthesis increased (P < 0.0001) during absorption of a mixed glucose amino acid meal in all groups. This increase in albumin synthesis accounted for 28% of the increase in whole body protein synthesis associated with feeding and for 24, 22, and 14% in the prednisone, rhGH, and combined treatment groups, respectively. These data suggest that the stimulation of albumin synthesis observed during feeding prevents irreversible oxidative losses of a significant fraction of ingested essential amino acids and may serve as a vehicle to capture excess dietary amino acids and transport them to peripheral tissues to sustain local protein synthesis.

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.

Skeletal and cardiac muscle protein turnover during short-term cold exposure and rewarming in young rats

1996 ◽  
Vol 270 (6) ◽  
pp. R1231-R1239 ◽  
Author(s):  
S. E. Samuels ◽  
J. R. Thompson ◽  
R. J. Christopherson
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Cold Exposure ◽  
Growth Rates ◽  
Protein Turnover ◽  
Short Term ◽  
Ad Libitum ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Young animals exposed to cold environmental temperatures typically have decreased skeletal muscle accretion but increased heart masses. To explore these phenomena, we measured protein synthesis and degradation in vivo in cardiac and skeletal muscle in weanling rats during short-term cold exposure and rewarming. Control rats were housed at 25 degrees C throughout the experiment. Ad libitum-fed and pair-fed (to the intake of controls) rats were housed at 5 degrees C (cold) for 5 days and then at 25 degrees C (rewarmed) for another 5 days. Cold exposure decreased rates of protein accretion and synthesis in skeletal muscle, whereas degradation did not differ. The effects of cold exposure on skeletal muscle were similar in both pair-fed and ad libitum-fed rats, except growth was lower in pair-fed rats. In cardiac muscle, cold exposure increased rates of protein synthesis and degradation and resulted in increased cardiac mass. Results in pair-fed animals generally fell between those of control and ad libitum-fed cold rats. During rewarming, growth rates were not higher in skeletal muscle in ad libitum-fed re-warmed rats, although protein turnover returned toward control values; in pair-fed rats, it remained lower. In heart, growth rates of ad libitum-fed and pair-fed rewarmed rats decreased due to lower protein synthesis rates. These alterations appear to be consistent with a strategy designed to improve survival in cold environments.

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