Faster protein and ribosome synthesis in thyroxine-induced hypertrophy of rat heart

1985 ◽  
Vol 248 (3) ◽  
pp. C309-C319 ◽  
Author(s):  
D. Siehl ◽  
B. H. Chua ◽  
N. Lautensack-Belser ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Single Injection ◽  
Plasma Concentrations ◽  
Bicarbonate Buffer ◽  
Ribosomal Subunits ◽  
Ribosome Synthesis ◽  
And Control ◽  
Perfused Hearts

Rates of protein synthesis and degradation were measured in hearts from normal and thyroxine-injected rats that were perfused as working preparations with Krebs-Henseleit bicarbonate buffer containing 400 microU insulin/ml, 2 mM lactate, 10 mM glucose, and normal plasma concentrations of amino acids. Hearts were perfused after four daily injections (1 microgram/g body wt) of thyroxine. Protein synthesis was 24% greater in hypertrophying hearts compared with controls; ribosomal RNA content increased 25%. In addition, the proportion of total RNA in free ribosomal subunits in hypertrophying hearts was unchanged from perfused hearts of control rats and from unperfused normal hearts. These results indicated that increased protein synthetic machinery as monitored by content of ribosomes, rather than more efficient initiation or elongation of peptide chains, accounted for the faster rate of protein synthesis in hypertrophying hearts. Rates of protein degradation were the same in hearts from thyroxine-injected and control animals. When rates of ribosome production were measured in vitro at various times after a single injection of thyroxine in vivo, faster ribosome synthesis was detected within 8 h; no change in the rate of total protein synthesis occurred after a single injection of thyroxine. These studies indicated that accelerated ribosome formation was an early and quantitatively important factor in cardiac hypertrophy.

Protein synthesis is required for rapid degradation of tubulin mRNA and other deflagellation-induced RNAs in Chlamydomonas reinhardi

1986 ◽  
Vol 6 (1) ◽  
pp. 54-61
Author(s):  
E J Baker ◽  
L R Keller ◽  
J A Schloss ◽  
J L Rosenbaum
Keyword(s):  
Protein Synthesis ◽  
Transcriptional Control ◽  
Protein S ◽  
Protein Synthesis Inhibitors ◽  
Control Factors ◽  
Flagellar Proteins ◽  
The Stability ◽  
And Control

After flagellar detachment in Chlamydomonas reinhardi, there is a rapid synthesis and accumulation of mRNAs for tubulin and other flagellar proteins. Maximum levels of these mRNAs (flagellar RNAs) are reached within 1 h after deflagellation, after which they are rapidly degraded to their predeflagellation levels. The degradation of alpha- and beta-tubulin RNAs was shown to be due to the shortening of their half-lives after accumulation (Baker et al., J. Cell Biol. 99:2074-2081, 1984). Deflagellation in the presence of protein synthesis inhibitors results in the accumulation of tubulin and other flagellar mRNAs by kinetics similar to those of controls. However, unlike controls, in which the accumulated mRNAs are rapidly degraded, these mRNAs are stabilized in cycloheximide. The stabilization by cycloheximide is specific for the flagellar mRNAs accumulated after deflagellation, since there is no change in the levels of flagellar mRNAs in nondeflagellated (uninduced) cells in the presence of cycloheximide. The kinetics of flagellar mRNA synthesis after deflagellation are shown to be the same in cycloheximide-treated and control cells by in vivo labeling and in vitro nuclear runoff experiments. These results show that protein synthesis is not required for the induced synthesis of flagellar mRNAs, and that all necessary transcriptional control factors are present in the cell before deflagellation, but that protein synthesis is required for the accelerated degradation of the accumulated flagellar mRNAs. Since cycloheximide prevents the induced synthesis and accumulation of flagellar proteins, it is possible that the product(s) of protein synthesis required for the accelerated decay of these mRNAs is a flagellar protein(s). The possibility that one or more flagellar proteins autoregulate the stability of the flagellar mRNAs is discussed.

scholarly journals THE INTRACELLULAR SITE OF SYNTHESIS OF MITOCHONDRIAL RIBOSOMAL PROTEINS IN NEUROSPORA CRASSA

1972 ◽  
Vol 54 (1) ◽  
pp. 56-74 ◽  
Author(s):  
Paul M. Lizardi ◽  
David J. L. Luck
Keyword(s):  
Protein Synthesis ◽  
Isoelectric Focusing ◽  
Gel Electrophoresis ◽  
Ribosomal Proteins ◽  
Mitochondrial Protein ◽  
Selective Inhibitor ◽  
Mitochondrial Protein Synthesis ◽  
Ribosomal Subunits

The intracellular site of synthesis of mitochondrial ribosomal proteins (MRP) in Neurospora crassa has been investigated using three complementary approaches. (a) Mitochondrial protein synthesis in vitro: Tritium-labeled proteins made by isolated mitochondria were compared to 14C-labeled marker MRP by cofractionation in a two-step procedure involving isoelectric focusing and polyacrylamide gel electrophoresis. Examination of the electrophoretic profiles showed that essentially none of the peaks of in vitro product corresponded exactly to any of the MRP marker peaks. (b) Sensitivity of in vivo MRP synthesis to chloramphenicol: Cells were labeled with leucine-3H in the presence of chloramphenicol, mitochondrial ribosomal subunits were subsequently isolated, and their proteins fractionated by isoelectric focusing followed by gel electrophoresis. The labeling of every single MRP was found to be insensitive to chloramphenicol, a selective inhibitor of mitochondrial protein synthesis. (c) Sensitivity of in vivo MRP synthesis to anisomycin: We have found this antibiotic to be a good selective inhibitor of cytoplasmic protein synthesis in Neurospora. In the presence of anisomycin the labeling of virtually all MRP is inhibited to the same extent as the labeling of cytoplasmic ribosomal proteins. On the basis of these three types of studies we conclude that most if not all 53 structural proteins of mitochondrial ribosomal subunits in Neurospora are synthesized by cytoplasmic ribosomes.

Polyribosome fractions and protein synthesis in stem rust infected wheat

1986 ◽  
Vol 64 (9) ◽  
pp. 1916-1927 ◽  
Author(s):  
Andrew Greenland ◽  
Michael Shaw
Keyword(s):  
Protein Synthesis ◽  
Stem Rust ◽  
Rust Fungus ◽  
High Molecular Mass ◽  
In Vitro Translation ◽  
Ribosomal Subunits ◽  
Two Dimensional Electrophoresis ◽  
Dimensional Electrophoresis

The effects of infection by stem-rust fungus on polyribosomal RNA fractions and protein synthesis in vitro and in vivo in near-isogenic resistant (Sr6) and susceptible (sr6) lines of wheat were determined. In infected resistant leaves the proportion of ribosomes present as polyribosomes was greater than that in healthy (uninfected) leaves at 1, 3, and 6 days and that in susceptible leaves at 1 and 3 days after inoculation. In the latter there were large increases in the pelletable RNA content (ribosomes, ribosomal subunits, and polyribosomes) and proportion of ribosomes present as polyribosomes from day 6. In vitro translation failed to detect any marked differences in polyribosomal translation products in resistant and susceptible leaves in response to infection. Labelling of polypeptides in vivo and separation by one- and two-dimensional electrophoresis showed that at 1 day after inoculation, two groups of high molecular mass polypeptides (80–96 and 100–110 kDa) were more heavily labelled and two novel polypeptides were present in resistant and susceptible leaves in response to infection. Synthesis of the high molecular weight and two novel polypeptides was maintained in infected resistant leaves up to 6 days after inoculation. In susceptible leaves the amount of radiolabel incorporated into these polypeptides and several proteins prominently labelled in uninfected controls declined rapidly from 3 days after inoculation.

Early Dissociation of Protein Synthesis and Amylase Secretion Following Hormonal Stimulation of the Pancreas

1974 ◽  
Vol 52 (2) ◽  
pp. 198-205 ◽  
Author(s):  
R. Mongeau ◽  
Y. Couture ◽  
J. Dunnigan ◽  
J. Morisset
Keyword(s):  
Protein Synthesis ◽  
Incubation Medium ◽  
Single Injection ◽  
Pancreatic Enzyme ◽  
Amylase Secretion ◽  
Hormonal Stimulation ◽  
Pancreatic Enzyme Secretion ◽  
Metabolic Conditions

The secretion of the various pancreatic enzymes can be increased by hormonal and cholinergic stimulation. However, it is not yet clear among the different investigators if their synthesis remains constant or can be modified according to different metabolic conditions. The secretion and synthesis of the pancreatic proteins were then studied in parallel to evaluate if secretion triggers synthesis or both phenomenons are controlled by separate mechanisms.The approach for these studies consists mainly in a combination of in vivo and in vitro experiments. The stimulants were injected in vivo and the pancreatic secretions were collected for different periods of time. The animals were then sacrificed and protein synthesis was measured in vitro along with the amylase secreted into the incubation medium. The results show that protein synthesis is decreased during the first 15 min after a single injection or infusion of both cholecystokinin–pancreozymin (CCK–PZ) and secretin. This reduction was associated with an increase in amylase secreted into the incubation medium. However, at 30 min after the hormonal stimulation, protein synthesis is increased while secretion into the incubation medium had returned to control levels. This increase in protein synthesis lasts for at least 1 h. These results strongly suggest that pancreatic enzyme secretion and synthesis are dissociated in the early minutes following hormonal stimulation.

scholarly journals Protein synthesis is required for rapid degradation of tubulin mRNA and other deflagellation-induced RNAs in Chlamydomonas reinhardi.

1986 ◽  
Vol 6 (1) ◽  
pp. 54-61 ◽  
Author(s):  
E J Baker ◽  
L R Keller ◽  
J A Schloss ◽  
J L Rosenbaum
Keyword(s):  
Protein Synthesis ◽  
Transcriptional Control ◽  
Protein S ◽  
Protein Synthesis Inhibitors ◽  
Control Factors ◽  
Flagellar Proteins ◽  
The Stability ◽  
And Control

After flagellar detachment in Chlamydomonas reinhardi, there is a rapid synthesis and accumulation of mRNAs for tubulin and other flagellar proteins. Maximum levels of these mRNAs (flagellar RNAs) are reached within 1 h after deflagellation, after which they are rapidly degraded to their predeflagellation levels. The degradation of alpha- and beta-tubulin RNAs was shown to be due to the shortening of their half-lives after accumulation (Baker et al., J. Cell Biol. 99:2074-2081, 1984). Deflagellation in the presence of protein synthesis inhibitors results in the accumulation of tubulin and other flagellar mRNAs by kinetics similar to those of controls. However, unlike controls, in which the accumulated mRNAs are rapidly degraded, these mRNAs are stabilized in cycloheximide. The stabilization by cycloheximide is specific for the flagellar mRNAs accumulated after deflagellation, since there is no change in the levels of flagellar mRNAs in nondeflagellated (uninduced) cells in the presence of cycloheximide. The kinetics of flagellar mRNA synthesis after deflagellation are shown to be the same in cycloheximide-treated and control cells by in vivo labeling and in vitro nuclear runoff experiments. These results show that protein synthesis is not required for the induced synthesis of flagellar mRNAs, and that all necessary transcriptional control factors are present in the cell before deflagellation, but that protein synthesis is required for the accelerated degradation of the accumulated flagellar mRNAs. Since cycloheximide prevents the induced synthesis and accumulation of flagellar proteins, it is possible that the product(s) of protein synthesis required for the accelerated decay of these mRNAs is a flagellar protein(s). The possibility that one or more flagellar proteins autoregulate the stability of the flagellar mRNAs is discussed.

‘Unmasking’ of stored maternal mRNAs and the activation of protein synthesis at fertilization in sea urchins

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 623-633 ◽  
Author(s):  
L.C. Kelso-Winemiller ◽  
M.M. Winkler
Keyword(s):  
Protein Synthesis ◽  
Sea Urchins ◽  
In Vitro Assay ◽  
Vitro Assay ◽  
Translational Machinery ◽  
Maternal Mrnas ◽  
Additional Support ◽  
And Control

The isolation and in vitro assay of maternal mRNPs has led to differing conclusions as to whether maternal mRNAs in sea urchin eggs are in a repressed or ‘masked’ form. To circumvent the problems involved with in vitro approaches, we have used an in vivo assay to determine if the availability of mRNA and/or components of the translational machinery are limiting protein synthesis in the unfertilized egg. This assay involves the use of a protein synthesis elongation inhibitor to create a situation in the egg in which there is excess translational machinery available to bind mRNA. Eggs were fertilized and the rate of entry into polysomes of individual mRNAs was measured in inhibitor-treated and control embryos using 32P-labeled cDNA probes. The fraction of ribosomes in polysomes and the polysome size were also determined. The results from this in vivo approach provide strong evidence for the coactivation of both mRNAs and components of the translational machinery following fertilization. The average polysome size increases from 7.5 ribosomes per message in 15 min embryos to approximately 10.8 ribosomes in 2 h embryos. This result gives additional support to the idea that translational machinery, as well as mRNA, is activated following fertilization. We also found that individual mRNAs are recruited into polysomes with different kinetics, and that the fraction of an mRNA in polysomes in the unfertilized egg correlates with the rate at which that mRNA is recruited into polysomes following fertilization.

Chloroquine reduces whole body proteolysis in humans

1994 ◽  
Vol 267 (1) ◽  
pp. E183-E186 ◽  
Author(s):  
P. De Feo ◽  
E. Volpi ◽  
P. Lucidi ◽  
G. Cruciani ◽  
F. Santeusanio ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Plasma Concentrations ◽  
Whole Body ◽  
Body Protein ◽  
Leucine Kinetics ◽  
Lysosomal Proteolysis ◽  
Therapeutic Doses

The antimalaric drug chloroquine is a well known inhibitor of lysosomal proteolysis in vitro. The present study tests the hypothesis that therapeutic doses of the drug decrease proteolysis also in vivo in humans. Leucine kinetics were determined in 20 healthy volunteers given 12 and 1.5 h before the studies 250 and 500 mg, respectively, of chloroquine phosphate (n = 10) or similar tablets of placebo (n = 10). Chloroquine reduced the rates of leucine appearance, a measure of whole body proteolysis, from 2.45 +/- 0.08 to 2.19 +/- 0.08 mumol.kg-1.min-1 (P = 0.038) and those of nonoxidative leucine disposal, an estimate of whole body protein synthesis, from 2.16 +/- 0.08 to 1.95 +/- 0.06 mumol.kg-1.min-1 (P = 0.050). The drug resulted also in a marginally significant (P = 0.051) decrement in the plasma concentrations of glucose. The effects of chloroquine on protein turnover might be potentially useful in counteracting protein wasting complicating several catabolic diseases, whereas those on glucose metabolism can explain the sporadic occurrence of severe hypoglycemic episodes in malaria patients chronically treated with this drug.

Immunisation against inhibin enhances follicular development, oocyte maturation and superovulatory response in water buffaloes

2011 ◽  
Vol 23 (6) ◽  
pp. 788 ◽  
Author(s):  
D. R. Li ◽  
G. S. Qin ◽  
Y. M. Wei ◽  
F. H. Lu ◽  
Q. S. Huang ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Plasma Concentrations ◽  
Follicular Development ◽  
Oocyte Quality ◽  
Control Group ◽  
High Group ◽  
Α Subunit ◽  
And Control

This study was carried out to test the feasibility of enhancing embryo production in vivo and in vitro by immunoneutralisation against inhibin or follistatin. In Experiment 1, multi-parity buffaloes were assigned into three groups: High group (n = 8), which received one primary (2 mg) and two booster (1 mg) vaccinations (28-day intervals) with a recombinant inhibin α subunit in 1 mL of white oil adjuvant; Low group (n = 8), which received half that dose; and Control group (n = 7), which received only adjuvant. Immunisation against inhibin stimulated development of ovarian follicles. Following superovulation and artificial insemination, inhibin-immunised buffaloes had more developing follicles than the Control buffaloes. The average number of embryos and unfertilised ova (4.5 ± 0.6, n = 6) in the High group was higher (P < 0.05) than in the Control group (2.8 ± 0.6, n = 5) and was intermediate (4.1 ± 0.7, n = 7) in the Low group. The pooled number of transferable embryos of the High and Low groups (3.2 ± 0.5, n = 13) was also higher (P < 0.05) than that (1.6 ± 0.7, n = 5) of the controls. The immunised groups also had higher plasma concentrations of activin, oestradiol and progesterone. In Experiment 2, the addition of anti-inhibin or anti-follistatin antibodies into buffalo oocyte IVM maturation medium significantly improved oocyte maturation and cleavage rates following parthenogenic activation. Treatment with anti-follistatin antibody also doubled the blastocyst yield from activated embryos. These results demonstrated that immunisation against inhibin stimulated follicular development, enhanced oocyte quality and maturation competence, yielded more and better embryos both in vivo and in vitro.

scholarly journals Rates of protein turnover in vivo and in vitro in ventricular muscle of hearts from fed and starved rats

1984 ◽  
Vol 222 (2) ◽  
pp. 395-400 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
N F Kearney ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Ventricular Muscle ◽  
Degradation Rates ◽  
Perfused Hearts

Starvation of 300 g rats for 3 days decreased ventricular-muscle total protein content and total RNA content by 15 and 22% respectively. Loss of body weight was about 15%. In glucose-perfused working rat hearts in vitro, 3 days of starvation inhibited rates of protein synthesis in ventricles by about 40-50% compared with fed controls. Although the RNA/protein ratio was decreased by about 10%, the major effect of starvation was to decrease the efficiency of protein synthesis (rate of protein synthesis relative to RNA). Insulin stimulated protein synthesis in ventricles of perfused hearts from fed rats by increasing the efficiency of protein synthesis. In vivo, protein-synthesis rates and efficiencies in ventricles from 3-day-starved rats were decreased by about 40% compared with fed controls. Protein-synthesis rates and efficiencies in ventricles from fed rats in vivo were similar to values in vitro when insulin was present in perfusates. In vivo, starvation increased the rate of protein degradation, but decreased it in the glucose-perfused heart in vitro. This contradiction can be rationalized when the effects of insulin are considered. Rates of protein degradation are similar in hearts of fed animals in vivo and in glucose/insulin-perfused hearts. Degradation rates are similar in hearts of starved animals in vivo and in hearts perfused with glucose alone. We conclude that the rates of protein turnover in the anterogradely perfused rat heart in vitro closely approximate to the rates in vivo in absolute terms, and that the effects of starvation in vivo are mirrored in vitro.

scholarly journals Inhibition of protein synthesis by glucagon in different rat muscles and protein fractions in vivo and in the perfused rat hemicorpus

1988 ◽  
Vol 251 (3) ◽  
pp. 727-732 ◽  
Author(s):  
V R Preedy ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Plasma Concentrations ◽  
Type I ◽  
Inhibition Of Protein Synthesis ◽  
Fasted Rats ◽  
Mixed Protein

The effect of glucagon on the rate of muscle protein synthesis was examined in vivo and in the isolated perfused rat hemicorpus. An inhibition of protein synthesis in skeletal muscles from overnight-fasted rats at various plasma concentrations of glucagon was demonstrated in vivo. The plantaris muscle (Type II, fibre-rich) was more sensitive than the soleus (Type I, fibre-rich). Myofibrillar and sarcoplasmic proteins were equally sensitive in vivo. However, protein synthesis in mixed protein and in sarcoplasmic and myofibrillar fractions of the heart was unresponsive to glucagon in vivo. In isolated perfused muscle preparations from fed animals, the addition of glucagon also decreased the synthesis of mixed muscle proteins in gastrocnemius (Type I and II fibres) and plantaris, but not in the soleus. The sarcoplasmic and myofibrillar fractions of the plantaris were also equally affected in vitro. Similar results were observed in vitro with 1-day-starved rats, but the changes were less marked.

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