scholarly journals An Increase in Liver Polyamine Concentration Contributes to the Tryptophan-Induced Acute Stimulation of Rat Hepatic Protein Synthesis

Nutrients ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2665
Author(s):  
Shinichiro Koike ◽  
Yukihito Kabuyama ◽  
Kodwo Amuzuah Obeng ◽  
Kunio Sugahara ◽  
Yusuke Sato ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Ornithine Aminotransferase ◽  
Polyamine Biosynthesis ◽  
Polyamine Synthesis ◽  
Unique Role ◽  
Differentially Expressed Protein ◽  
Hepatic Protein Synthesis ◽  
Fasted Rats ◽  
Stimulation Of

Tryptophan has a unique role as a nutritional signaling molecule that regulates protein synthesis in mouse and rat liver. However, the mechanism underlying the stimulating actions of tryptophan on hepatic protein synthesis remains unclear. Proteomic and metabolomic analyses were performed to identify candidate proteins and metabolites likely to play a role in the stimulation of protein synthesis by tryptophan. Overnight-fasted rats were orally administered L-tryptophan and then sacrificed 1 or 3 h after administration. Four differentially expressed protein spots were detected in rat liver at 3 h after tryptophan administration, of which one was identified as an ornithine aminotransferase (OAT) precursor. OAT is the main catabolic enzyme for ornithine, and its expression was significantly decreased by tryptophan administration. The concentration of ornithine was increased in the liver at 3 h after tryptophan administration. Ornithine is a precursor for polyamine biosynthesis. Significantly increased concentrations of polyamines were found in the liver at 3 h after administration of tryptophan. Additionally, enhanced hepatic protein synthesis was demonstrated by oral administration of putrescine. We speculate that the increase in ornithine level through suppression of OAT expression by tryptophan administration may lead to accelerated polyamine synthesis, thereby promoting protein synthesis in the liver.

scholarly journals Biotin-mediated protein biosynthesis

1974 ◽  
Vol 140 (3) ◽  
pp. 549-556 ◽  
Author(s):  
R. L. Boeckx ◽  
K. Dakshinamurti
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Liver ◽  
Intestinal Mucosa ◽  
Protein Biosynthesis ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Stimulation Of

The effect of administration of biotin to biotin-deficient rats on protein biosynthesis was studied. Biotin treatment resulted in stimulation by more than twofold of amino acid incorporation into protein, both in vivo and in vitro in rat liver, pancreas, intestinal mucosa and skin. Analysis of the products of amino acid incorporation into liver proteins in vivo and in vitro indicated that the synthesis of some proteins was stimulated more than twofold, but others were not stimulated at all. This indicates a specificity in the stimulation of protein synthesis mediated by biotin.

scholarly journals Effects of the hepatotoxic agents retrorsine and aflatoxin B1 on hepatic protein synthesis in the rat

1968 ◽  
Vol 109 (1) ◽  
pp. 87-91 ◽  
Author(s):  
S. Villa-Treviño ◽  
D. D. Leaver
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Aflatoxin B1 ◽  
Plasma Proteins ◽  
Pyrrolizidine Alkaloid ◽  
Main Site ◽  
Nuclear Rna ◽  
Hepatic Protein Synthesis

1. Aflatoxin and the pyrrolizidine alkaloid retrorsine inhibited the incorporation of labelled amino acids into rat liver and plasma proteins in vivo. Inhibition was greater and detected earlier with retrorsine (1hr.) than with aflatoxin (3hr.). 2. Both toxins affected the liver ribosomal aggregates, causing increases in the proportion of monomers plus dimers. The effect of retrorsine was greater than that of aflatoxin. 3. Incorporation of labelled amino acids into proteins of cell-free preparations of liver from rats treated with aflatoxin was lower than in control preparations. The main site of inhibition appeared to be the ribosomes. 4. Both toxins inhibited the incorporation of orotate into liver nuclear RNA 1hr. after administration.

scholarly journals Enhancement of the anti-anabolic response to adenosine 3′:5′-cyclic monophosphate during development. The inhibition of hepatic protein synthesis

1977 ◽  
Vol 168 (2) ◽  
pp. 271-275 ◽  
Author(s):  
A Klaipongpan ◽  
D P Bloxham ◽  
M Akhtar
Keyword(s):  
Protein Synthesis ◽  
Cyclic Amp ◽  
Rat Liver ◽  
Anabolic Response ◽  
Cyclic Monophosphate ◽  
Age Dependent ◽  
Inhibition Of Protein Synthesis ◽  
Dependent Inhibition ◽  
Hepatic Protein Synthesis

Cyclic AMP causes an age-dependent inhibition of protein synthesis in rat liver. The onset of inhibition is about 10—12 days after birth. The developmental response to cyclic AMP is associated with a change in the microsomal component of the protein-synthesizing system.

scholarly journals Insulin stimulates synthesis of soluble proteins in isolated rat hepatocytes

1980 ◽  
Vol 190 (3) ◽  
pp. 615-619 ◽  
Author(s):  
R L Clark ◽  
R J Hansen
Keyword(s):  
Protein Synthesis ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Cellular Protein ◽  
Soluble Proteins ◽  
Leucine Incorporation ◽  
Isolated Rat Hepatocytes ◽  
Hepatic Protein Synthesis ◽  
Isolated Rat ◽  
Stimulation Of

The incorporation of [3H]leucine into soluble cellular protein was measured in isolated hepatocytes at extracellular leucine concentrations ranging from 0.15 to 20.0 mM. Insulin caused a 12—15% stimulation of [3H]leucine incorporation in the presence of high extracellular leucine concentrations. It is concluded that insulin causes a small but significant increase in the rate of hepatic protein synthesis.

The influence of plasma concentrations of tri-iodothyronine on the acute increases in insulin and muscle protein synthesis in the refed fasted rat

1988 ◽  
Vol 118 (3) ◽  
pp. 417-422 ◽  
Author(s):  
D. J. Millward ◽  
J. G. Brown ◽  
J. van Bueren
Keyword(s):  
Protein Synthesis ◽  
Insulin Secretion ◽  
Plasma Insulin ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Plasma Concentrations ◽  
Plasma Insulin Levels ◽  
Fasted Rats ◽  
Stimulation Of ◽  
Fast Insulin

ABSTRACT To examine whether the low plasma levels of triiodothyronine (T3) in fasted rats might limit the recovery of muscle protein synthesis on refeeding, rats were fasted for either 3 or 4 days and refed with or without pretreatment with thyroid hormones. Fasting suppressed T3 levels, plasma insulin and the rate of the translational phase of muscle protein synthesis (KRNA; the rate per unit RNA), especially after the 4-day fast. On refeeding, plasma T3 levels remained low for more than 3 h after the 3-day fast and for more than 8 h after the 4-day fast. Insulin concentrations increased within the first hour of refeeding, eventually achieving supranormal concentrations after the 3-day fast. The KRNA increased within the first hour of refeeding, achieving well-fed control values by 3 h after the 3-day fast or 24 h after the 4-day fast. The increases in KRNA were significantly correlated with the increases in insulin at low insulin concentrations, achieving a plateau value at 150 pmol/l, so that further increases in insulin were not associated with any further increases in protein synthesis. Pretreatment with thyroid hormone induced increased T3 levels which were maintained for up to 8 h of refeeding. This had no effect on the responses of either insulin or protein synthesis to refeeding after the 3-day fast, but did result in an acceleration of the recovery in the KRNA and plasma insulin levels in the rats fasted for 4 days. Analysis of the insulin–KRNA relationship showed no evidence for any increase in the insulin sensitivity of muscle protein synthesis with thyroid pretreatment, the initial stimulation of protein synthesis on refeeding the rats fasted for 4 days reflecting increased insulin secretion. Since in the untreated animals, insulin secretion on refeeding was also correlated with T3 levels, these results are consistent with the previously reported thyroidal dependence of insulin secretion. J. Endocr. (1988) 118, 417–422

Hepatic protein synthesis in the regenerating rat liver after hepatopancreatectomy

Surgery Today ◽  
1997 ◽  
Vol 27 (6) ◽  
pp. 511-517 ◽  
Author(s):  
Keiichi Okano ◽  
Taijirou Tsubouchi ◽  
Yohichi Yamashita ◽  
Hisao Wakabayashi ◽  
Takashi Maeba ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Regenerating Rat Liver ◽  
Hepatic Protein Synthesis
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