scholarly journals Early stimulation of rat liver microsomal protein synthesis after tri-iodothyronine injection in vivo

1979 ◽  
Vol 182 (3) ◽  
pp. 651-654 ◽  
Author(s):  
W J Carter ◽  
F H Faas
Keyword(s):  
Protein Synthesis ◽  
Rna Synthesis ◽  
Microsomal Protein ◽  
Physiological Significance ◽  
Direct Stimulation ◽  
Early Effect ◽  
Alpha Amanitin ◽  
Stimulation Of

In an effort to determine the physiological significance of previous studies showing stimulation of microsomal protein synthesis by thyroxine added in vitro, an early effect of tri-iodothyronine injected in vivo was sought. Tri-iodothyronine (25 micrograms/100 g) administered to euthyroid rats stimulated microsomal protein synthesis in vitro within 3–6 h. This effect occurred much earlier than the 26 h lag previously reported after tri-iodothyronine administration to hypothyroid rats. This early effect of tri-iodothyronine on protein synthesis is prevented by alpha-amanitin, suggesting that it is dependent on RNA synthesis. The failure to find a direct effect in vivo of tri-iodothyronine on translation casts doubt on the physiological significance of previous studies that have shown a direct stimulation of translation by thyroxine added in vitro.

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.

Cellular heterogeneity of uridine incorporation in collecting tubules: effect of DOCA

1985 ◽  
Vol 248 (4) ◽  
pp. F552-F564
Author(s):  
A. Vandewalle ◽  
F. Cluzeaud ◽  
M. Chavance ◽  
J. P. Bonvalet
Keyword(s):  
Rna Synthesis ◽  
Cellular Heterogeneity ◽  
Nuclear Surface ◽  
Intercalated Cells ◽  
Uridine Incorporation ◽  
Collecting Tubules ◽  
Silver Grains ◽  
Stimulation Of

In previous studies we showed that in vitro uridine incorporation along the renal tubule is heterogeneous and that DOCA induces a stimulation of RNA synthesis in distal cortical and medullary structures. The present work examines by autoradiography of isolated tubules and renal tissue sections the cellular heterogeneity of the connecting (CNT) and cortical collecting (CCT) tubules after in vivo injection of [3H]uridine in normal and DOCA-treated rabbits. Data confirmed the profile of uridine incorporation along the tubule, which was found in in vitro experiments, and the DOCA-induced stimulation of RNA synthesis. In microdissected CNT and CCT of control kidneys, statistical analysis of the distribution of labeling revealed the presence of two distinct cell populations: one with low labeling (2-3 silver grains per nucleus) and one with high labeling (10-13), which represent 64 and 36%, respectively (CNT), and 74 and 26%, respectively (CCT), of the whole population. Histological data showed that the respective proportions of intercalated cells (29% in CNT; 21% in CCT) and connecting tubule cells (65%) or principal cells (79%) are close to those of the populations with high or low labeling. In addition, autoradiographs on renal sections directly demonstrated that the labeling of intercalated cells (19.3 silver grains/100 micron2 nuclear surface in CNT; 14.7 in CCT) was three times higher than that of connecting (6.6) or principal (5.8) cells. In isolated CNT and CCT, DOCA induced similar absolute increases in the labeling of the two populations. However, the relative increase was more than two times higher in the population with low labeling (+131% in CNT, +210% in CCT) than in the one with high labeling (+71% and +98%). We conclude that cell population of the collecting cortical tubule (CNT and CCT) is heterogeneous with regard to uridine incorporation, reflecting RNA synthesis.

scholarly journals Direct Stimulation of Adult Neural Stem Cells In Vitro and Neurogenesis In Vivo by Vascular Endothelial Growth Factor

2006 ◽  
Vol 14 (3) ◽  
pp. 237-248 ◽  
Author(s):  
Anne Schänzer ◽  
Frank-Peter Wachs ◽  
Daniel Wilhelm ◽  
Till Acker ◽  
Christiana Cooper-Kuhn ◽  
...  
Keyword(s):  
Stem Cells ◽  
Vascular Endothelial Growth Factor ◽  
Growth Factor ◽  
Neural Stem Cells ◽  
Vascular Endothelial ◽  
Direct Stimulation ◽  
Endothelial Growth Factor ◽  
Stimulation Of

scholarly journals Mechanism of Stimulation of Plus-Strand Synthesis by an RNA Replication Enhancer in a Tombusvirus

2005 ◽  
Vol 79 (15) ◽  
pp. 9777-9785 ◽  
Author(s):  
Tadas Panavas ◽  
Peter D. Nagy
Keyword(s):  
Rna Synthesis ◽  
Rna Viruses ◽  
Rna Replication ◽  
Dual Function ◽  
Long Distance ◽  
Replication Assay ◽  
Rna Interaction ◽  
Stimulation Of

ABSTRACT Replication of RNA viruses is regulated by cis-acting RNA elements, including promoters, replication silencers, and replication enhancers (REN). To dissect the function of an REN element involved in plus-strand RNA synthesis, we developed an in vitro trans-replication assay for tombusviruses, which are small plus-strand RNA viruses. In this assay, two RNA strands were tethered together via short complementary regions with the REN present in the nontemplate RNA, whereas the promoter was located in the template RNA. We found that the template activity of the tombusvirus replicase preparation was stimulated in trans by the REN, suggesting that the REN is a functional enhancer when located in the vicinity of the promoter. In addition, this study revealed that the REN has dual function during RNA synthesis. (i) It binds to the viral replicase. (ii) It interacts with the core plus-strand initiation promoter via a long-distance RNA-RNA interaction, which leads to stimulation of initiation of plus-strand RNA synthesis by the replicase in vitro. We also observed that this RNA-RNA interaction increased the in vivo accumulation and competitiveness of defective interfering RNA, a model template. We propose that REN is important for asymmetrical viral RNA replication that leads to more abundant plus-strand RNA progeny than the minus-strand intermediate, a hallmark of replication of plus-strand RNA viruses.

In vitro transcription of RNA in nuclei, nucleoli and chromatin from physarum polycephalum

1977 ◽  
Vol 26 (1) ◽  
pp. 267-279
Author(s):  
K.E. Davies ◽  
I.O. Walker
Keyword(s):  
Rna Polymerase ◽  
Physarum Polycephalum ◽  
Rna Synthesis ◽  
In Vitro Transcription ◽  
Polymerase Activity ◽  
Controlled Conditions ◽  
Rna Polymerase Activity ◽  
Alpha Amanitin

Methods for isolating nuclei, nucleoli and chromatin from Physarum polycephalum which retain high levels of endogenous RNA polymerase activity are described. Under carefully controlled conditions with respect to mono- and divalent cation concentrations RNA synthesis in nuclei displayed linear kinetics for at least 30 min and the RNA products had a similar size distribution to nuclear RNA synthesis observed in vivo. Chromatin showed 60% of the nuclear transcriptional activity but no conditions were found where faithful transcription of the template occurred. Isolated nucleoli were 5-fold more active than nuclei and the endogenous RNA polymerase activity was insensitive to alpha-amanitin. Under carefully controlled conditions, the nucleoli appeared to support the accurate transcription, re-initiation and processing of rRNA chains in vitro.

THYROXINE STIMULATION OF AMINO ACID INCORPORATION INTO MITOCHONDRIAL PROTEIN: DIFFERENCES BETWEEN IN VIVO AND IN VITRO EFFECTS

1973 ◽  
Vol 72 (4) ◽  
pp. 684-696 ◽  
Author(s):  
Amirav Gordon ◽  
Martin I. Surks ◽  
Jack H. Oppenheimer
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Mitochondrial Protein ◽  
Leucine Incorporation ◽  
Mitochondrial Protein Synthesis ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Stimulation Of

ABSTRACT The in vivo and in vitro stimulation of rat hepatic mitochondrial protein synthesis by thyroxine (T4) was compared. In confirmation of Buchanan & Tapley (1966). T4 added to isolated mitochondria rapidly stimulated [14C] leucine incorporation into mitochondrial protein. The in vitro stimulation was reversed after T4 was removed by incubating the mitochondria with bovine serum albumin (BSA). The decrease in T4 stimulation of protein synthesis appeared proportional to the T4 removed by BSA. Thus, it appears probable that exchangeable T4 controls the in vitro system. In contrast, the increase in mitochondrial protein synthesis which was observed 3 to 4 days after pretreatment of hypothyroid rats with labelled and non-radioactive T4 was not reversed by BSA treatment. Moreover, mitochondrial radioactivity could not be extracted with albumin. The in vivo phenomenon does not, therefore, appear to be related to exchangeable hormone in the mitochondria. Furthermore, the estimated quantity of T4 associated with mitochondria after in vivo stimulation was at least two orders of magnitude less than that required to produce comparable stimulation of mitochondrial protein synthesis in vitro. These findings strongly suggest that in vitro and in vivo stimulation of amino acid incorporation by T4 may be mediated by different biochemical mechanisms.

Extreme hyperinsulinemia unmasks insulin’s effect to stimulate protein synthesis in the human forearm

1998 ◽  
Vol 274 (6) ◽  
pp. E1067-E1074 ◽  
Author(s):  
Teresa A. Hillier ◽  
David A. Fryburg ◽  
Linda A. Jahn ◽  
Eugene J. Barrett
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
In Vivo Studies ◽  
Skeletal Muscle Protein ◽  
High Concentrations ◽  
Arterial Plasma ◽  
Stimulation Of

Insulin clearly stimulates skeletal muscle protein synthesis in vitro. Surprisingly, this effect has been difficult to reproduce in vivo. As in vitro studies have typically used much higher insulin concentrations than in vivo studies, we examined whether these concentration differences could explain the discrepancy between in vitro and in vivo observations. In 14 healthy volunteers, we raised forearm insulin concentrations 1,000-fold above basal levels while maintaining euglycemia for 4 h. Amino acids (AA) were given to either maintain basal arterial ( n = 4) or venous plasma ( n = 6) AA or increment arterial plasma AA by 100% ( n = 4) in the forearm. We measured forearm muscle glucose, lactate, oxygen, phenylalanine balance, and [3H]phenylalanine kinetics at baseline and at 4 h of insulin infusion. Extreme hyperinsulinemia strongly reversed postabsorptive muscle’s phenylalanine balance from a net release to an uptake ( P < 0.001). This marked anabolic effect resulted from a dramatic stimulation of protein synthesis ( P < 0.01) and a modest decline in protein degradation. Furthermore, this effect was seen even when basal arterial or venous aminoacidemia was maintained. With marked hyperinsulinemia, protein synthesis increased further when plasma AA concentrations were also increased ( P< 0.05). Forearm blood flow rose at least twofold with the combined insulin and AA infusion ( P< 0.01), and this was consistent in all groups. These results demonstrate an effect of high concentrations of insulin to markedly stimulate muscle protein synthesis in vivo in adults, even when AA concentrations are not increased. This is similar to prior in vitro reports but distinct from physiological hyperinsulinemia in vivo where stimulation of protein synthesis does not occur. Therefore, the current findings suggest that the differences in insulin concentrations used in prior studies may largely explain the previously reported discrepancy between insulin action on protein synthesis in adult muscle in vivo vs. in vitro.

scholarly journals Some Biochemical and Histological Effects of 2-Chloroethanol in Rats

1992 ◽  
Vol 1 (3) ◽  
pp. 37-56 ◽  
Author(s):  
Leonard Friedman ◽  
John Scalera ◽  
James E. Keys ◽  
Edmund L. Peters ◽  
Dennis W. Gaines ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rna Synthesis ◽  
Liver Lipid ◽  
Intraperitoneal Administration ◽  
Female Rats ◽  
Male Rats ◽  
Liver Protein ◽  
Adult Rats

The effects of 2-chioroethanol (2-CE) on rat tissue following in vitro and in vivo exposure were studied. At concentrations as low as 2.5 mg/ml, protein synthesis in liver slices was inhibited; at concentrations of 25 mg/ml and above, RNA synthesis and respiration were also impaired. Single oral doses of 2-CE to young adult rats at levels of 15-40 mg/kg body weight depressed liver nonprotein sulfhydryl (GSH) concentration and liver protein but not RNA synthesis. Liver lipid was increased by 7 hr after a single oral dose of 30 mg/kg. The time courses and dose-response relationship for GSH depletion and restoration and for protein synthesis inhibition and recovery were similar. The livers of female rats were more sensitive than the livers of male rats to the effects of 2-CE. Protein synthesis was also depressed in kidneys of 2-CE-treated male rats but at higher doses than those needed for this effect to occur in livers of the same animals. Liver polysome disaggregation also occurred after oral 2-CE doses of 20 mg/kg and greater. The effects of 2-CE on ribosome profiles and protein synthesis were at least partially reversed by concurrent intraperitoneal administration of cysteine. The possible relationship of these findings to a role of GSH in protein synthesis is discussed.

scholarly journals Ethanol raises prostacyclin in vivo and in vitro

Blood ◽  
1984 ◽  
Vol 64 (3) ◽  
pp. 679-682
Author(s):  
R Landolfi ◽  
M Steiner
Keyword(s):  
Endothelial Cells ◽  
Significant Rise ◽  
Blood Alcohol ◽  
Elevated Plasma ◽  
Direct Stimulation ◽  
Baseline Values ◽  
Induced Changes ◽  
Stimulation Of

Moderate doses of ethanol were shown to induce a significant rise in prostacyclin (PGI2) concentration in cultures of endothelial cells derived from umbilical veins. Administration of 32 g of ethanol to six volunteers elevated plasma levels of PGI2 in parallel with those of blood alcohol. Although not specific for ethanol, this alcohol induced the largest change in PGI2. Withdrawal of the stimulant alcohol caused prompt reduction of the elevated prostacyclin to baseline values. The activity of ethanol appears to be due to a direct stimulation of cyclooxygenase. The release of [14C]arachidonic acid from prelabeled endothelial cells was decreased by ethanol. PGE2 production was also enhanced by exposure of endothelial cells to ethanol. The physiologic significance of these alcohol-induced changes in PGI2 levels remains to be established.

RNA polymerase II subunit composition, stoichiometry, and phosphorylation

1990 ◽  
Vol 10 (5) ◽  
pp. 1915-1920 ◽  
Author(s):  
P A Kolodziej ◽  
N Woychik ◽  
S M Liao ◽  
R A Young
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Rna Synthesis ◽  
Subunit Composition ◽  
Subunit Gene ◽  
Cell Extracts ◽  
Alpha Amanitin

RNA polymerase II subunit composition, stoichiometry, and phosphorylation were investigated in Saccharomyces cerevisiae by attaching an epitope coding sequence to a well-characterized RNA polymerase II subunit gene (RPB3) and by immunoprecipitating the product of this gene with its associated polypeptides. The immunopurified enzyme catalyzed alpha-amanitin-sensitive RNA synthesis in vitro. The 10 polypeptides that immunoprecipitated were identical in size and number to those previously described for RNA polymerase II purified by conventional column chromatography. The relative stoichiometry of the subunits was deduced from knowledge of the sequence of the subunits and from the extent of labeling with [35S]methionine. Immunoprecipitation from 32P-labeled cell extracts revealed that three of the subunits, RPB1, RPB2, and RPB6, are phosphorylated in vivo. Phosphorylated and unphosphorylated forms of RPB1 could be distinguished; approximately half of the RNA polymerase II molecules contained a phosphorylated RPB1 subunit. These results more precisely define the subunit composition and phosphorylation of a eucaryotic RNA polymerase II enzyme.

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