scholarly journals Regulation of mammalian protein synthesis in vivo. Stimulated liver ribonucleic acid synthesis in vivo after cycloheximide treatment

1977 ◽  
Vol 168 (1) ◽  
pp. 57-63 ◽  
Author(s):  
J J Ch'ih ◽  
L M Pike ◽  
T M Devlin
Keyword(s):  
Protein Synthesis ◽  
Lethal Dose ◽  
Kinetic Studies ◽  
Acid Synthesis ◽  
Ribonucleoprotein Complexes ◽  
Nuclear Rna ◽  
Membrane Bound ◽  
Cellulose Column ◽  
Mammalian Protein

1. As shown by a double-radioisotope technique in vivo, at a non-lethal dose of cycloheximide, a stimulation of nuclear RNA synthesis occurred by 12 h after the treatment; the stimulation lasted over 48 h. Analysis of radioactive nuclear RNA by gel electrophoresis demonstrated that most of the cycloheximide-stimulated synthesis could be accounted for by known rRNA precursors (45 S, 41 S, 32 S and 28 S). 2. During the inhibitory phase of protein synthesis, 2 h after cycloheximide treatment, synthesis of the poly(A)-containing mRNA isolated from the cytoplasmic ribonucleoprotein complexes with an oligo(dT)-cellulose column was stimulated, whereas the synthesis of rRNA was slightly inhibited. However, during the stimulatory phase of protein synthesis, 24 h after cycloheximide treatment, the syntheses of both poly(A)-containing mRNA and rRNA were enhanced. 3. Kinetic studies revealed that the newly synthesized RNA species were transported from the nuclei, integrated into the ribonucleoprotein complexes, and associated with both free and membrane-bound polyribosomes. 4. These data corroborate our proposal that the stimulated protein synthesis after cycloheximide administration involves gene transcription.

scholarly journals Regulation of mammalian protein synthesis in vivo. Simulated transport of nuclear ribonucleoprotein complexes to the cytoplasm after cycloheximide treatment

1979 ◽  
Vol 178 (3) ◽  
pp. 643-649 ◽  
Author(s):  
J J Ch'ih ◽  
D M Duhl ◽  
L S Faulkner ◽  
T M Devlin
Keyword(s):  
Protein Synthesis ◽  
Gradient Centrifugation ◽  
Lethal Dose ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Ribonucleoprotein Complexes ◽  
Treatment Analysis ◽  
Nuclear Ribonucleoprotein ◽  
Mammalian Protein

By studies in vivo with purified nuclei from rat liver, it was shown that a non-lethal dose of cycloheximide causes a decrease in the content of total nuclear ribonucleoprotein complexes by 2h after treatment. Analysis of the complex by sucrose-density-gradient centrifugation substantiated this observation for the faster-sedimenting complex, but showed an increase in the content of a smaller complex. Radioisotope incorporation studies showed that the overall decrease in nuclear ribonucleoprotein content was not due to a decreased synthesis, but rather to an increased transport to the cytoplasm. The results of a double-radioisotope technique support the conclusion that, during the inhibitory phase of protein synthesis brough on by cycloheximdie, gene transcription continues and the gene product is transported to the cytoplasm for subsequent translation.

scholarly journals Regulation of mammalian protein synthesis in vivo. Stimulated protein synthesis in liver in vivo after cycloheximide treatment

1977 ◽  
Vol 162 (3) ◽  
pp. 501-507 ◽  
Author(s):  
J J Ch'ih ◽  
R Procyk ◽  
T M Devlin
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Proteins ◽  
Lethal Dose ◽  
Recovery Phase ◽  
Leucine Incorporation ◽  
Membrane Bound ◽  
Differential Pattern ◽  
Ribosomal Protein Synthesis ◽  
Mammalian Protein

Protein synthesis in rat liver in vivo was measured between 0 and 72 h after administration of a non-lethal dose of cycloheximide. There was a period of inhibition of [3H]leucine incorporation into both intra- and extra-cellular proteins at 2 h after administration of the drug, which was followed by a recovery phase in which amino acid incorporation varied significantly among the various proteins evaluated. At 12 h there was a marked stimulation of incorporation into nascent polypeptides released from polyribosomes and plasma fibrinogen, but incorporation into ribosomal proteins as well as albumin was still inhibited. Between 12 and 48 h, nascent-polypeptide synthesis remained elevated, but ribosomal-protein synthesis recovered slowly from the inhibition to normal rates only, and plasma-albumin synthesis increased slowly to above control values up to 48 h before returning to normal. A differential pattern of incorporation was also observed for incorporation into free and membrane-bound polyribosomes.

scholarly journals Effect of post-ischaemic recovery on albumin synthesis and relative amount of translatable albumin messenger RNA in rat liver

1982 ◽  
Vol 204 (1) ◽  
pp. 197-202 ◽  
Author(s):  
G Cairo ◽  
L Schiaffonati ◽  
M G Aletti ◽  
A Bernelli-Zazzera
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Messenger Rna ◽  
Relative Proportion ◽  
Liver Homogenate ◽  
Albumin Synthesis ◽  
Specific Proteins ◽  
Membrane Bound ◽  
Albumin Mrna

In liver cells recovering from reversible ischaemia, total protein synthesis by postmitochondrial supernatant and membrane-bound and free polyribosomes is not different from that in sham-operated controls. However, the relative proportion of specific proteins is changed, since the incorporation of [3H]leucine in vivo into liver albumin, relative to incorporation into total protein, as determined by precipitation of labelled albumin with the specific antibody, decreases by 40-50% in post-ischaemic livers. Cell-free synthesis by membrane-bound polyribosomes and poly(A)-enriched RNA isolated from unfractionated liver homogenate shows that the decrease in albumin synthesis in liver of rats recovering from ischaemia is due to the relative decrease in translatable albumin mRNA.

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 Studies on the mechanism for entry of vesicular stomatitis virus glycoprotein g mRNA into membrane-bound polyribosome complexes

1977 ◽  
Vol 74 (1) ◽  
pp. 43-57 ◽  
Author(s):  
MJ Grubman ◽  
JA Weinstein ◽  
DA Shafritz
Keyword(s):  
Protein Synthesis ◽  
Vesicular Stomatitis Virus ◽  
Cytosol Fraction ◽  
Initial Event ◽  
Glycoprotein G ◽  
Nonspecific Effects ◽  
Membrane Bound ◽  
Vesicular Stomatitis

Glycoprotein mRNA (G mRNA) of vesicular stomatitis virus is synthesized in the cytosol fraction of infected HeLa cells. Shortly after synthesis, this mRNA associates with 40S ribosomal subunits and subsequently forms 80S monosomes in the cytosol fraction. The bulk of labeled G mRNA is then found in polysomes associated with the membrane, without first appearing in the subunit or monomer pool of the membrane-bound fraction. Inhibition of the initiation of protein synthesis by pactamycin or muconomycin A blocks entry of newly synthesized G m RNA into membrane-bound polysomes. Under these circumstances, labeled G mRNA accumulates into the cytosol. Inhibition of the elongation of protein synthesis by cucloheximide, however, allows entry of 60 percent of newly synthesized G mRNA into membrane-bound polysomes. Furthermore, prelabeled G mRNA associated with membrane-bound polysomes is released from the membrane fraction in vivo by pactamycin or mucomycon A and in vitro by 1mM puromycin - 0.5 M KCI. This release is not due to nonspecific effects of the drugs. These results demonstrate that association of G mRNA with membrane-bound polysomes is dependent upon polysome formation and initiation of protein synthesis. Therefore, direct association of the 3' end of G mRNA with the membrane does not appear to be the initial event in the formation of membrane-bound polysomes.

scholarly journals A possible mechanism of inhibition of protein synthesis by dimethylnitrosamine

1967 ◽  
Vol 105 (2) ◽  
pp. 625-631 ◽  
Author(s):  
S. Villa-Treviño
Keyword(s):  
Protein Synthesis ◽  
Messenger Rna ◽  
Transfer Rna ◽  
The State ◽  
Leucine Incorporation ◽  
Mechanism Of Inhibition ◽  
Nuclear Rna ◽  
Inhibition Of Protein Synthesis ◽  
Hepatic Protein Synthesis

1. The incorporation of [14C]leucine into liver proteins of rats was measured in vivo at various times after treatment of the animals with dimethylnitrosamine and was correlated with the state of the liver ribosomal aggregates. Inhibition of incorporation ran parallel with breakdown of the aggregates. 2. Inhibition of leucine incorporation into protein and breakdown of ribosomal aggregates were not preceded by inhibition of incorporation of [14C]orotate into nuclear RNA of the liver. 3. Evidence was obtained of methylation of nuclear RNA in the livers of rats treated with [14C]dimethylnitrosamine. 4. Zonal centrifugation analysis of radioactive, nuclear, ribosomal and transfer RNA from livers of rats treated with [14C]dimethylnitrosamine revealed labelling of all centrifugal fractions to about the same extent. 5. It is suggested that methylation of messenger RNA might occur in the livers of dimethylnitrosamine-treated rats and the possible relation of this to inhibition of hepatic protein synthesis is discussed.

scholarly journals Factors controlling aminoacyl-transfer-ribonucleic acid synthesis in vitro by a plant system

1971 ◽  
Vol 121 (3) ◽  
pp. 495-501 ◽  
Author(s):  
K. L. Tao ◽  
T. C. Hall
Keyword(s):  
Protein Synthesis ◽  
Acid Synthesis ◽  
Regulatory Function ◽  
Factors Affecting ◽  
Trna Species ◽  
Aminoacyl Transfer ◽  
Leaf System ◽  
Bean Leaves

1. Factors affecting aminoacyl-tRNA synthesis in vitro by cell-free preparations from bean leaves were investigated. 2. Evidence was obtained that optimum concentrations as well as correct ratios of Mg2+ and ATP are required for aminoacyl-tRNA synthesis in the bean-leaf system. 3. The results indicated that pH is a controlling factor having differential effects on the formation of individual aminoacyl-tRNA species. The possible micro-regulatory function of pH in protein synthesis in vivo is discussed with special reference to alanyl-tRNA formation. 4. Very low rates of alanine-stimulated pyrophosphate exchange were observed in the absence of tRNA. This observation is discussed relative to proposals about the mechanism of aminoacyl-tRNA synthesis.

scholarly journals Regulation of mammalian protein synthesis in vivo. Protein synthesis in rat liver and kidney after the administration of sublethal doses of cyclohyximide

1976 ◽  
Vol 156 (1) ◽  
pp. 151-157 ◽  
Author(s):  
L I Rothblum ◽  
T M Devlin ◽  
J J Ch'ih
Keyword(s):  
Protein Synthesis ◽  
Specific Radioactivity ◽  
Cellular Protein ◽  
Leucine Incorporation ◽  
Precursor Pool ◽  
Liver And Kidney ◽  
Sublethal Doses ◽  
Mammalian Protein ◽  
Stimulation Of

Protein synthesis in vivo was studied at various times after the administration of sublethal doses of cycloheximide to rats. Cycloheximide caused an inhibition, followed by a dose-and time-dependent stimulation, of incorportation of labelled precursor into proteins of the liver and kidney. The stimulation of protein synthesis at 24h was not due to a change of precursor pool or the specific radioactivity of the precursor used. During the stimulatory period, leucine incorporation into various cellular protein fractions varied; incorporation into total nuclear protein was the most affected.

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