scholarly journals Glucosamine metabolism in regenerating rat liver

1976 ◽  
Vol 158 (3) ◽  
pp. 589-592 ◽  
Author(s):  
N Akamatsu ◽  
H Nakajima ◽  
S Miyata
Keyword(s):  
Partial Hepatectomy ◽  
Rat Liver ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Amino Sugar ◽  
Insoluble Fraction ◽  
Regenerating Liver ◽  
Glycoprotein Synthesis

1. Glycoprotein synthesis was investigated with [1-14C]glucosamine in vivo. [14C]Glucosamine was administered intravenously 24h after hepatectomy to rats. 2. Incorporation into the acid-soluble fraction was maximum at 15 min after injection both in sham-operated and hepatectomized rats. 3. Enhancement of incorporation into UDP-N-acetylhexosamine in regenerating liver was observed. However, its specific activity was lower, because of a greater enhancement of synthesis de novo of the amino sugar. 4. In the liver acid-insoluble fraction, maximum incorporation of [14C]glucosamine was at 30 min in sham-operated rats and 2 h in hepatectomized rats respectively. 5. In sham-operated rats, incorporation into the plasma acid-insoluble fraction followed that of the liver acid-insoluble fraction, but hepatectomy resulted in a rapid enchancement of incorporation into plasma. 6. It is concluded that synthesis of liver glycoproteins is stimulated after partial hepatectomy and that glycoproteins synthesized are released rapidly into the plasma.

DEOXYCYTIDYLATE DEAMINASE LEVELS IN REGENERATING RAT LIVER

1961 ◽  
Vol 39 (6) ◽  
pp. 1043-1054 ◽  
Author(s):  
D. K. Myers ◽  
C. Anne Hemphill ◽  
Constance M. Townsend
Keyword(s):  
Dna Synthesis ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Deoxyribonucleic Acid ◽  
Regenerating Liver ◽  
Regenerating Rat Liver ◽  
High Level ◽  
Early Regeneration

Deoxycytidylate deaminase activity and net synthesis of deoxyribonucleic acid (DNA) in vivo were found to increase at approximately the same time during the early stages of liver regeneration. However, deaminase activity in the regenerating liver remained at a high level for 1 day after DNA synthesis had slowed down again during the later stages of regeneration. The increase in deaminase activity was restricted as a result of exposure to 600 r X radiation during early regeneration, but this effect only became evident 11–16 hours after the irradiation. Irradiation on the second day after partial hepatectomy, when deaminase levels in control regenerating livers were relatively constant, failed to affect the deaminase activity immediately but did produce a 40–50% decrease in activity 11–16 hours later. Other antimitotic agents, e.g., colchicine, had little effect on deaminase activity.

scholarly journals Phosphatidylethanolamine metabolism in rat liver after partial hepatectomy. Control of biosynthesis of phosphatidylethanolamine by the availability of ethanolamine

1992 ◽  
Vol 283 (1) ◽  
pp. 55-61 ◽  
Author(s):  
M Houweling ◽  
L B M Tijburg ◽  
W J Vaartjes ◽  
L M G van Golde
Keyword(s):  
Partial Hepatectomy ◽  
Rat Liver ◽  
Sham Operation ◽  
Regenerating Liver ◽  
Ethanolamine Kinase ◽  
Time Period

The effect of partial (70%) hepatectomy on phosphatidylethanolamine (PE) synthesis was studied in rat liver during the first 4 post-operative days. Between 4 and 96 h after partial hepatectomy, the mass of PE increased from 30% to 80% of sham-operation values. In line with the increase in PE mass, the rate of PE synthesis in vivo from [14C]ethanolamine was stimulated 1.6- and 1.3-fold at 22 and 48 h after partial hepatectomy respectively. Surprisingly, the activity of CTP:phosphoethanolamine cytidylyltransferase (EC 2.7.7.14) was virtually unchanged after partial hepatectomy. In addition, neither ethanolamine kinase (EC 2.7.1.82) nor ethanolaminephosphotransferase (EC 2.7.8.1) showed any changes in activity over the time period studied. Hepatic levels of ethanolamine and phosphoethanolamine were drastically increased after partial hepatectomy, as compared with sham operation, whereas levels of CDP-ethanolamine and microsomal diacylglycerol were not affected. Interestingly, partial hepatectomy caused the concentration of free ethanolamine in serum to increase from 29 microM to approx. 50 microM during the first day after surgery. In hepatocytes isolated from non-operated animals, incorporation of [3H]ethanolamine into PE was stimulated by increasing the ethanolamine concentration from 10 up to 50 microM, whereas the radioactivity associated with phosphoethanolamine only increased at ethanolamine concentrations higher than 30 microM. Taken together, our results indicate that the observed increase in serum ethanolamine concentration after partial hepatectomy is probably responsible for both the increase in PE biosynthesis and the accumulation of ethanolamine and phosphoethanolamine in regenerating liver.

Structural and Metabolic Interrelationships Among Glycerophosphatides of Rat Liver In Vivo

1971 ◽  
Vol 49 (12) ◽  
pp. 1347-1356 ◽  
Author(s):  
B. J. Holub ◽  
A. Kuksis
Keyword(s):  
Rat Liver ◽  
De Novo ◽  
Specific Activity ◽  
Acyl Transfer ◽  
De Novo Synthesis ◽  
Individual Molecular Species ◽  
Relative Specific Activity ◽  
Proportional Contribution ◽  
Specific Activities

The specific activities of individual molecular species of rat liver diacylglycerylphosphorocholine (PC), diacylglycerylphosphoroethanolamine (PE), and diacylglycerophosphorylinositol (MPI) were determined and compared following intravenous injection of glycerol-14C. PC, PE, and MPI contained 41, 51, and 83%, respectively, tetraenoic species, and 40,17, and 9% combined mono-, di-, and trienoic species. The rest of the phosphatide mass of PC, PE, and MPI was contributed by 18, 32, and 8% penta- and hexaenoic species, respectively. The proportions of chemical classes of the glycerophosphatides differed by 1.1- to 18-fold while the fatty acid associations within the unsaturation classes common to these phosphatides varied 2.2- to 17-fold. After 5 min exposure to radioactive glycerol, the mono-, di-, and trienoic species of the PC, PE, and MPI possessed 13–18, 15–50, and 6–42 times, respectively, the specific activity of the tetraenes of the corresponding phosphatide classes. While the pentaenoic and hexaenoic species of PC and MPI had specific activities three to five times those of the respective tetraenes, the higher polyenes of PE were considerably more radioactive and approached the specific activity of the dienoic species of this phosphatide. With progressing time up to 60 min, the tetraenoic species of PC, PE, and MPI showed increases in relative specific activity of 50, 64, and 109%, respectively, in the three phosphatides. These results are consistent with an effective de novo synthesis of the oligoenoic species and a transacylation of the tetraenoic species of all liver glycerophosphatides tested. The proportional contribution of de novo synthesis in comparison to acyl transfer is apparently greater to the formation of PC and PE than to that of MPI.

scholarly journals Uptake of amino acids and nucleic acid precursors by regenerating rat liver

1972 ◽  
Vol 129 (1) ◽  
pp. 175-181 ◽  
Author(s):  
Margery G. Ord ◽  
L. A. Stocken
Keyword(s):  
Amino Acids ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Orotic Acid ◽  
Soluble Fraction ◽  
Plasma Concentrations ◽  
Regenerating Liver ◽  
Nuclear Rna ◽  
S Period ◽  
Intracellular Acid

1. At 0.5–1.0h after partial hepatectomy the intracellular acid-soluble fraction of rat liver took up twice as much radioactivity from [3H]orotic acid, [3H]uridine and [3H]thymidine as did similar fractions from sham-operated animals. This increase in penetration was not prevented by adrenalectomy or actinomycin, both of which decreased precursor uptake into nuclear RNA at this time. The increase in entry was still shown by thymidine at 22h after operation, at the height of the S period. Adenine penetration was not increased 1h after partial hepatectomy. 2. Plasma concentrations of ornithine and possibly methionine, tyrosine and lysine were raised 1.5h after partial hepatectomy. [3H]Lysine entry into regenerating liver at this time was increased by 60% [3H]valine uptake was unaffected. Intracellular amounts of tyrosine, phenylalanine and ornithine in the liver were also increased. 3. The relation of these events to the start of liver regeneration is discussed.

scholarly journals REUTILIZATION OF LYMPHOCYTE DNA BY CELLS OF INTESTINAL CRYPTS AND REGENERATING LIVER

1963 ◽  
Vol 18 (3) ◽  
pp. 515-523 ◽  
Author(s):  
B. J. Bryant
Keyword(s):  
Partial Hepatectomy ◽  
De Novo ◽  
Living Cells ◽  
Lymphoid Organs ◽  
Lymphoid Cells ◽  
Intestinal Cells ◽  
Regenerating Liver ◽  
Peyer's Patch ◽  
Intestinal Crypt ◽  
Recipient Liver

Lymphoid cells from mice injected 54 hours and 30 hours earlier with 3H-thymidine were washed and transfused into isogenic recipients at 29 to 30 hours after partial hepatectomy. The recipients were killed 28 to 30 hours later, and liver, intestine, Peyer's patch, spleen, and the transfused cells were examined in autoradiographs exposed 6 months. Approximately 80 per cent of the labeled transfused cells were classed as lymphocytes. The labeled DNA contained in the transfused cells was partitioned to about 14 times as many recipient liver and intestinal cells, appearing in 72 to 78 per cent of hepatocyte nuclei, in 30 to 35 per cent of liver reticuloendothelial nuclei, and in 90 to 95 per cent of intestinal crypt nuclei. The label was not comparably widespread in the lymphoid organs, but was limited to a few intensely labeled lymphocytes and a somewhat larger number of very weakly labeled cells. When heat-killed cells rather than living cells were transfused, intensely labeled lymphocytes were absent from the lymphoid organs, but the labeling of cells in the recipients was otherwise identical. The results suggest that (a) reutilized DNA is derived from dead cells, (b) reutilized DNA is mainly degraded to nucleosides and nucleotides, the usual immediate de novo DNA precursors, before reincorporation into DNA, and (c) DNA reutilization may occur in the lymphoid organs, but on a less active scale than in intestine or regenerating liver.

scholarly journals De Novo Design of Granulopoietic Proteins

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 34-35
Author(s):  
Julia Skokowa ◽  
Mohammad Elgamacy ◽  
Patrick Müller
Keyword(s):  
Protein Design ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Specific Activity ◽  
Structural Information ◽  
Coiled Coil ◽  
Design Strategies ◽  
Nmr Structure Determination ◽  
Binding Epitope

Protein therapeutics are clinically developed and used as minorly engineered forms of their natural templates. This direct adoption of natural proteins in therapeutic contexts very frequently faces major challenges, including instability, poor solubility, and aggregation, which may result in undesired clinical outcomes. In contrast to classical protein engineering techniques, de novo protein design enables the introduction of radical sequence and structure manipulations, which can be used to address these challenges. In this work, we test the utility of two different design strategies to design novel granulopoietic proteins, using structural information from human granulocyte-colony stimulating factor (hG-CSF) as a template. The two strategies are: (1) An epitope rescaffolding where we migrate a tertiary structural epitope to simpler, idealised, proteins scaffolds (Fig. 1A-C), and (2) a topological refactoring strategy, where we change the protein fold by rearranging connections across the secondary structures and optimised the designed sequence of the new fold (Fig. 1A,D,E). Testing only eight designs, we obtained novel granulopoietic proteins that bind to the G-CSF receptor, have nanomolar activity in cell-based assays, and were highly thermostable and protease-resistant. NMR structure determination showed three designs to match their designed coordinates within less than 2.5 Å. While the designs possessed starkly different sequence and structure from the native G-CSF, they showed very specific activity in differentiating primary human haematopoietic stem cells into fully mature granulocytes. Morever, one design shows significant and specific activity in vivo in zebrafish and mice. These results are prospectively directing us to investigate the role of dimerisation geometry of G-GCSF receptor on activation magnitude and downstream signalling pathways. More broadly, the results also motivate our ongoing work on to design other heamatopoietic agents. In conclusion, our findings highlight the utility of computational protein design as a highly effective and guided means for discovering nover receptor modulators, and to obtain new mechanistic information about the target molecule. Figure 1. Two different strategies to generate superfolding G-CSF designs. (A) X-ray structure of G-CSF (orange) bound to its cognate receptor (red) through its binding epitope (blue). According to the epitope rescaffolding strategy, (B) the critical binding epitope residues were disembodied and used as a geometric search query against the entire Protein Data Bank (PDB) to retrieve structurally compatible scaffolds. The top six compatible scaffolds structures are shown in cartoon representation. (C) The top two templates chosen for sequence design, were a de novo designed coiled-coil and a four-helix bundle with unknown function. The binding epitopes were grafted, and the scaffolds were optimised to rigidly host the guest epitope. (D-E) According to the topological refactoring strategy (D) the topology of the native G-CSF was rewired from around the fixed binding epitope, and then was further mutated to idealise the core residues (blue volume (E)) and residues distal from the binding epitope (orange crust (E)). Both strategies aimed at simplifying the topology, reducing the size, and rigidifying the bound epitope conformation through alternate means. Figure 1 Disclosures No relevant conflicts of interest to declare.

scholarly journals Post-transcriptional regulation of ribosome formation in the nucleus of regenerating rat liver

1983 ◽  
Vol 210 (1) ◽  
pp. 183-192 ◽  
Author(s):  
K P Dudov ◽  
M D Dabeva
Keyword(s):  
Rat Liver ◽  
Ribosome Biogenesis ◽  
Rrna Processing ◽  
Regenerating Liver ◽  
Regenerating Rat Liver ◽  
Rrna Species ◽  
Rrna Maturation ◽  
The Individual ◽  
Post Transcriptional Regulation

Kinetic experiments on RNA labelling in vivo with [14C]orotate were performed with normal and 12h-regenerating rat liver. The specific radioactivities of nucleolar, nucleoplasmic and cytoplasmic rRNA species were analysed by computer according to the models of rRNA processing and nucleo-cytoplasmic migration given previously [Dudov, Dabeva, Hadjiolov & Todorov, Biochem. J. (1978) 171, 375-383]. The rates of formation and the half-lives of the individual pre-rRNA and rRNA species were determined in both normal and regenerating liver. The results show clearly that the formation of ribosomes in regenerating rat liver is post-transcriptionally activated: (a) the half-lives of all the nucleolar pre-rRNA and rRNA species are decreased by 30% on average; (b) the pre-rRNA processing is directed through the shortest maturation pathway: 45 S leads to 32 S + 18 S leads to 28 S; (c) the nucleo-cytoplasmic transfer of ribosomes is accelerated. As a consequence, the time for formation and appearance of ribosomes in the cytoplasm is shortened 1.5-fold for the large and 2-fold for the small subparticle. A new scheme for endonuclease cleavage of 45 S pre-rRNA is proposed, which explains the alterations in pre-rRNA processing in regenerating liver. Its validity for pre-rRNA processing in other eukaryotes is discussed. It is concluded that: (i) the control sites in the intranucleolar formation of 28 S and 18 S rRNA are the immediate precursor of 28 S rRNA, 32 S pre-rRNA, and the primary pre-rRNA, 45 S pre-rRNA, respectively; (ii) the limiting step in the post-transcriptional stages of ribosome biogenesis is the pre-rRNA maturation.

scholarly journals Properties and developmental regulation of an α-d-galactosidase from Dictyostelium discoideum

1976 ◽  
Vol 158 (2) ◽  
pp. 409-417 ◽  
Author(s):  
D C Kilpatrick ◽  
J L Stirling
Keyword(s):  
Protein Synthesis ◽  
Dictyostelium Discoideum ◽  
Early Development ◽  
Subcellular Distribution ◽  
De Novo ◽  
Specific Activity ◽  
Soluble Fraction ◽  
Developmental Regulation ◽  
Cellular Slime Mould ◽  
Cellular Slime

An alpha-D-galactosidase was detected in cells of the cellular slime mould, Dictyostelium discoideum, at all stages of development. Its specific activity was highest during early development (interphase), and this accumulation of enzyme appears to require protein synthesis de novo. Its subcellular distribution differs from that of other D. discoideum glycosidases, since most activity was recovered in the soluble fraction. No evidence was obtained for more than one isoenzymic form after subjection of extracts to electrophoresis and various chromatographic procedures. It is excreted from the cell during development, but no evidence was found for an extracellular function for the enzyme.

Incorporation in vivo of [32P]orthophosphate and [Me-3H]choline into rough microsomal, Golgi, and plasma membranes of rat liver

1977 ◽  
Vol 55 (8) ◽  
pp. 876-885 ◽  
Author(s):  
Patricia L. Chang ◽  
John R. Riordan ◽  
Mario A. Moscarello ◽  
Jennifer M. Sturgess
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Specific Radioactivity ◽  
Marker Enzyme ◽  
Golgi Membranes ◽  
Endomembrane Flow

To study membrane biogenesis and to test the validity of the endomembrane flow hypothesis, incorporation of 32P and [Me-3H]choline in vivo into membranes of the rat liver was followed. Rough microsomal, Golgi-rich, and plasma membrane fractions were monitored with marker enzyme assays and shown with morphometric analysis to contain 82% rough microsomes, at least 70% Golgi complexes, and 88% plasma membranes, respectively. Membrane subfractions from the rough microsomal and Golgi-rich fractions were prepared by sonic disruption.At 5 to 30 min after 32P injection, the specific radioactivity of phosphatidylcholine was higher in the rough microsomal membranes than in the Golgi membranes. From 1 to 3 h, the specific activity of phosphatidylcholine in Golgi membranes became higher and reached the maximum at about 3 h. Although the plasma membrane had the lowest specific radioactivity throughout 0.25–3 h, it increased rapidly thereafter to attain the highest specific activity at 5 h. Both rough microsomal and plasma membranes reached their maxima at 5 h.The specific radioactivity of [32P]phosphatidylethanolamine in the three membrane fractions was similar to that of [32P]phosphatidylcholine except from 5 to 30 min, when the specific radioactivity of phosphatidylethanolamine in the Golgi membranes was similar to the rough microsomal membranes.At 15 min to 5 h after [Me-3H]choline injection, more than 90% of the radioactivity in all the membranes was acid-precipitable. The specific radioactivities of the acid-precipitated membranes, expressed as dpm per milligram protein, reached the maximum at 3 h. After [Me-3H]choline injection, the specific radioactivity of phosphatidylcholine separated from the lipid extract of the acid-precipitated membranes (dpm per micromole phosphorus) did not differ significantly in the three membrane fractions. The results indicated rapid incorporation of choline into membrane phosphatidylcholine by the rough endoplasmic reticulum, Golgi, and plasma membranes simultaneously.The data with both 32P and [Me-3H]choline precursors did not support the endomembrane flow hypothesis. The Golgi complexes apparently synthesized phosphatidylethanolamine and incorporated choline into phosphatidylcholine as well as the endoplasmic reticulum. The results are discussed with relevance to current hypotheses on the biogenesis and transfer of membrane phospholipids.

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