Effects of aminooxyacetate, alanine and other amino acids on protein synthesis in isolated rat hepatocytes

1978 ◽  
Vol 520 (3) ◽  
pp. 630-641 ◽  
Author(s):  
Per O. Seglen ◽  
Anne E. Solheim
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

scholarly journals Effects of amino acids, ammonia and leupeptin on protein synthesis and degradation in isolated rat hepatocytes

1978 ◽  
Vol 174 (2) ◽  
pp. 469-474 ◽  
Author(s):  
P O Seglen
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Specific Radioactivity ◽  
Rat Hepatocytes ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Isolated Rat Hepatocytes ◽  
Lysosomal Protein ◽  
Isolated Rat

Protein synthesis in isolated rat hepatocytes, as measured by the incorporation of [14C]-valine at constant specific radioactivity, proceeded at a rate of 0.3-0.5%/h in an unsupplemented medium, i.e. only about one-tenth the rate of protein degradation (4%/h). Leupeptin, which inhibits lysosomal protein degradation (previously found to be 75% of the total degradation in hepatocytes), had no effect on protein synthesis, showing that endogenous protein degradation supplied amino acids in excess of the substrate requirements for protein synthesis. The inhibition of protein synthesis by NH4Cl (another inhibitor of lysosomal protein degradation) as well as the stimulation by a physiological amino acid mixture must therefore represent indirect effects, either on general energy metabolism, or on unknown regulatory processes.

Effect of amino acid deprivation on initiation of protein synthesis in rat hepatocytes

1989 ◽  
Vol 256 (1) ◽  
pp. C18-C27 ◽  
Author(s):  
W. V. Everson ◽  
K. E. Flaim ◽  
D. M. Susco ◽  
S. R. Kimball ◽  
L. S. Jefferson
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Hepatocytes ◽  
Initiation Factor ◽  
Synthetic Activity ◽  
Perfused Liver ◽  
Amino Acid Deprivation ◽  
Isolated Rat Hepatocytes ◽  
Reticulocyte Lysate

Conditions were defined for maintaining optimal protein synthetic activity in suspensions of freshly isolated rat hepatocytes. Under these conditions, isolated hepatocytes exhibited rates of protein synthesis and levels of polysomal aggregation equivalent to those observed in vivo and in perfused liver. Deprivation of total amino acids or single, essential amino acids resulted in a rapid decrease in the rate of protein synthesis, which was readily reversed by readdition of the deficient amino acid(s). The decrease was accompanied by a disaggregation of polysomes and an inhibition of 43S initiation complex formation, which was indicative of a limitation in the rate of initiation of protein synthesis. Extracts prepared from perfused liver deprived of amino acids were inhibitory to initiation of protein synthesis in reticulocyte lysate. The inhibition in reticulocyte lysate was accompanied by an increase in phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF-2), suggesting activation of an eIF-2 alpha kinase or inhibition of a phosphatase in amino acid-deprived hepatocytes. This suggestion was confirmed by prelabeling hepatocytes with 32Pi before amino acid deprivation. Incorporation of 32Pi into eIF-2 alpha was two- to threefold higher in lysine-deprived cells than in hepatocytes incubated in fully supplemented medium. Overall, the results indicated that an increase in eIF-2 alpha phosphorylation was responsible for the defect in initiation of protein synthesis caused by amino acid deprivation.

Signalling pathways and combinatory effects of insulin and amino acids in isolated rat hepatocytes

2002 ◽  
Vol 269 (15) ◽  
pp. 3742-3750 ◽  
Author(s):  
Ulrike Krause ◽  
Luc Bertrand ◽  
Liliane Maisin ◽  
Maria Rosa ◽  
Louis Hue
Keyword(s):  
Amino Acids ◽  
Rat Hepatocytes ◽  
Signalling Pathways ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

Amiloride inhibits protein synthesis in isolated rat hepatocytes

Life Sciences ◽  
1981 ◽  
Vol 28 (11) ◽  
pp. 1295-1302 ◽  
Author(s):  
Max Fehlmann ◽  
Michel Samson ◽  
Katherine S. Koch ◽  
Hyam L. Leffert ◽  
Pierre Freychet
Keyword(s):  
Protein Synthesis ◽  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

AMINO ACID CONTROL OF PROTEIN SYNTHESIS AND DEGRADATION IN ISOLATED RAT HEPATOCYTES*

1980 ◽  
Vol 349 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Per O. Seglen ◽  
Anne E. Solheim ◽  
Bjørn Grinde ◽  
Paul B. Gordon ◽  
Per E. Schwarze ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Acid Control ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation ◽  
Isolated Rat

scholarly journals Microcystin-LR induced an inhibition of protein synthesis in isolated rat hepatocytes

1995 ◽  
Vol 306 (3) ◽  
pp. 693-696 ◽  
Author(s):  
S Claeyssens ◽  
A Francois ◽  
A Chedeville ◽  
A Lavoinne
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Hepatocytes ◽  
Mitochondrial Fraction ◽  
Maximum Effect ◽  
Isolated Rat Hepatocytes ◽  
Phosphatase Inhibitors ◽  
Protein Phosphatase Inhibitors ◽  
Phosphatase Activation ◽  
Isolated Rat

The effect of microcystin-LR, an inhibitor of protein phosphatases PP1 and PP2A, was studied on protein synthesis by measuring the incorporation of labelled amino acid into protein in isolated rat hepatocytes. Microcystin-LR inhibited protein synthesis in the first minutes of the incubation period, and half-maximum effect was obtained at about 60 nM. Such an inhibition was also observed in the presence of different protein phosphatase inhibitors, i.e. okadaic acid, calyculin A and microcystin-RR. This effect was observed in whole hepatocytes, in the supernatant of the post-mitochondrial fraction and in the microsomal fraction. It was independent of a substrate supply and of the labelled amino acid used. Furthermore, this inhibition preceded the previously reported glucose-6-phosphatase activation induced by microcystin-LR [Claeyssens, Chédeville and Lavoinne (1993) FEBS Lett. 315, 7-10].

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