Changes in protein synthesis during the development of Xenopus laevis

Development ◽  
1979 ◽  
Vol 51 (1) ◽  
pp. 137-153
Author(s):  
J. E. M. Ballantine ◽  
H. R. Woodland ◽  
E. A. Sturgess
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Gene Activity ◽  
Specific Gene ◽  
Two Dimensional Gel Electrophoresis ◽  
Free System ◽  
Stage Of Development ◽  
New Gene ◽  
Made In

Patterns of protein synthesis during the development of Xenopus were studied by two-dimensional gel electrophoresis. Up to the end of the blastula stage we find no newly synthesized proteins which are not already made in the oocyte. The first new proteins are seen during gastrulation, and they increase in number during neurulation. Some of these are restricted to the ‘ectodermal’ region, and some to the ‘endodermal’ region of embryos divided into two parts. These new, region-specific proteins include α-actin. When the oocyte matures the number of detectable newly synthesized proteins decreases, reaching a minimum in the unfertilized egg. Some, such as β- and γ-actin, re-appear at the end of cleavage. This could not be shown to be a recovery artifact. The relation of the total mRNA to these changes in protein synthesis was studied by translation in the lysed reticulocyte cell-free system. The mRNAs that code for oocyte proteins that cease synthesis in the unfertilized egg and re-appear in blastulae are nevertheless detectable in total RNA made from eggs. These proteins therefore seem to cease and resume synthesis through translational control. mRNAs for new proteins first appear after gastrulation, just when these proteins are first detected in vivo. This strongly suggests, though it does not prove, that new gene activity is involved. It is therefore likely that region-specific gene activity is already present by the gastrula stage of development, and has an impact on the most abundant kinds of proteins made in the embryo.

Processing of the precursor to a chloroplast ribosomal protein made in the cytosol occurs in two steps, one of which depends on a protein made in the chloroplast

1985 ◽  
Vol 5 (5) ◽  
pp. 1093-1099
Author(s):  
R J Schmidt ◽  
N W Gillham ◽  
J E Boynton
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Apparent Molecular Weight ◽  
Protein L ◽  
Mature Form ◽  
Chloroplast Protein Synthesis ◽  
Made In

In pulse-chase experiments in which log-phase cells of Chlamydomonas reinhardtii were labeled in vivo for 5 min with H2(35)SO4, fluorographs of immunoprecipitates from whole cell extracts revealed that chloroplast ribosomal proteins L-2, L-6, L-21, and L-29, which are made in the cytosol and imported, appeared in their mature forms. However, in the case of chloroplast ribosomal protein L-18, which is also made in the cytoplasm and imported, a prominent precursor with an apparent molecular weight of 17,000 was found at the end of a 5-min pulse. This precursor was processed to its mature size (apparent molecular weight of 15,500) within the first 5 min of the subsequent chase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the precursor to L-18 formed in vivo was 1.5 kilodaltons smaller than the primary product detected in translations of Chlamydomonas polyadenylated RNA in vitro. Upon a 10-min incubation with a postribosomal supernatant from Chlamydomonas, the 18,500-dalton precursor detected in vitro could be partially converted into a polypeptide that comigrated with the 17,000-dalton precursor detected in extracts of cells labeled in vivo. Under conditions in which the total amounts of chloroplast proteins had been reduced and cells were made to synthesize ribosomes rapidly, the apparent half-life of the 17,000-dalton precursor was extended over that seen in log-phase cells. When chloroplast protein synthesis was inhibited with lincomycin for 3 h before labeling under these conditions, the 17,000-dalton L-18 precursor but not the mature form was found, and the precursor was slowly degraded during a 60-min chase. When cells were placed in the dark for 3 h before labeling, processing of this precursor to the mature form appeared unaffected, but the chloroplast-synthesized ribosomal protein L-26 was detected, indicating that chloroplast protein synthesis was still occurring. We interpret these results to indicate that the maturation of protein L-18 in vivo involves at least two processing steps, one of which depends on a protein made on chloroplast ribosomes.

scholarly journals Eukaryotic initiation factors and protein synthesis after resistance exercise in rats

2000 ◽  
Vol 88 (3) ◽  
pp. 1036-1042 ◽  
Author(s):  
Peter A. Farrell ◽  
Jazmir M. Hernandez ◽  
Mark J. Fedele ◽  
Thomas C. Vary ◽  
Scot R. Kimball ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Translational Control ◽  
Sprague Dawley ◽  
Initiation Factors ◽  
Eukaryotic Initiation Factors ◽  
Sprague Dawley Rats ◽  
Arterial Plasma ◽  
Response To Exercise

Translational control of protein synthesis depends on numerous eukaryotic initiation factors (eIFs) and we have previously shown ( Am. J. Physiol. Endocrinol. Metab. 276: E721–E727, 1999) that increases in one factor, eIF2B, are associated with increases in rates of protein synthesis after resistance exercise in rats. In the present study we investigated whether the eIF4E family of initiation factors is also involved with an anabolic response to exercise. Male Sprague-Dawley rats either remained sedentary ( n = 6) or performed acute resistance exercise ( n = 6), and rates of protein synthesis were assessed in vivo 16 h after the last session of resistance exercise. eIF4E complexed to eIF4G (eIF4E ⋅ eIF4G), eIF4E binding protein 1 (4E-BP1) complexed to eIF4E, and phosphorylation state of eIF4E and 4E-BP1 (γ-form) were assessed in gastrocnemius. Rates of protein synthesis were higher in exercised rats compared with sedentary rats [205 ± 8 (SE) vs. 164 ± 5.5 nmol phenylalanine incorporated ⋅ g muscle−1 ⋅ h−1, respectively; P < 0.05]. Arterial plasma insulin concentrations were not different between the two groups. A trend ( P = 0.09) for an increase in eIF4E ⋅ eIF4G with exercise was noted; however, no statistically significant differences were observed in any of the components of the eIF4E family in response to resistance exercise. These new data, along with our previous report on eIF2B, suggest that the regulation of peptide chain initiation after exercise is more dependent on eIF2B than on the eIF4E system.

Aortic perfusion pressure as early determinant of beta-isomyosin expression in perfused hearts

1992 ◽  
Vol 263 (5) ◽  
pp. H1537-H1545
Author(s):  
C. Delcayre ◽  
D. Klug ◽  
V. T. Nguyen ◽  
C. Mouas ◽  
B. Swynghedauw
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Stress Protein ◽  
Pressure Overload ◽  
Aortic Pressure ◽  
Mechanical Stimulus ◽  
Beating Heart ◽  
Specific Gene ◽  
Coronary Pressure

Pressure overload in vivo induces an increase in cardiac protooncogene and stress protein expression that may initiate the long-term genetic changes observed in hypertrophy. To known whether mechanical stimulus is linked to specific gene transcription, expression of immediate early genes and synthesis of total proteins and myosin heavy chains (MHCs) were studied in beating and KCl-arrested isolated rat hearts perfused for 2 h under various coronary pressures. The main result of this study is that in the beating heart an augmentation of aortic pressure from 60 to 120 mmHg results in a pronounced enhancement of the synthesis of MHC (+59%) and of the expression of the beta-MHC isomyosin mRNA (iso-mRNA; +104%). Also, total protein synthesis and the amounts of poly-(A)+, c-fos, c-myc, and heat-shock protein HSP68 mRNAs were increased. To arrest the heart at 60 mmHg has no effect on total protein synthesis and on the amounts of poly(A)+, alpha-MHC and beta-MHC iso-mRNAs, and mRNAs coding for oncoproteins, but the synthesis of MHC decreased by 24%. By contrast with what we have observed in the beating heart, the augmentation of the coronary pressure in the arrested heart stimulates total protein synthesis and increases the amount of poly(A)+, c-fos, c-myc, and HSP68 mRNAs but has no effect on the expression of both MHC iso-mRNAs. In conclusion, the activation of myosin synthesis by high coronary pressure in this model has mainly a pretranslational origin when the heart is beating.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of tumor proteolysis by TNF-alpha: correlation of in vivo isotope estimates with growth

1991 ◽  
Vol 261 (1) ◽  
pp. R106-R116
Author(s):  
N. W. Istfan ◽  
P. R. Ling ◽  
G. L. Blackburn ◽  
B. R. Bistrian
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Whole Body ◽  
Independent Effect ◽  
Yoshida Sarcoma ◽  
Protein Breakdown ◽  
Body Protein ◽  
Breakdown Rates ◽  
Made In

To evaluate the accuracy of in vivo estimates of protein synthesis and breakdown, measurements of plasma and tissue leucine kinetics were made in rat tumor tissues at different conditions of growth by use of constant intravenous infusion of [14C]leucine. These measurements were made in Yoshida sarcoma tumors on days 10 and 13 after implantation, with and without tumor necrosis factor (TNF) infusion and on day 10 in Walker-256 carcinosarcoma. Expressed as micromoles of leucine per gram tissue, tumor protein breakdown increased (P less than 0.01) from 0.32 +/- 0.02 to 0.52 +/- 0.09 (SE) mumol/h, with progress of the Yoshida sarcoma tumor between days 10 and 13 after implantation. Similarly, TNF increased tumor proteolysis on day 10 (0.43 +/- 0.03 mumol.h-1.g-1, P less than 0.05 vs. day 10 control) but not on day 13 after implantation of the Yoshida tumor. Estimates of growth derived from the difference between protein synthesis and breakdown rates were not statistically different from those based on actual tumor volume changes in both tumor models. However, estimates of “whole body” protein metabolism (plasma leucine flux) were not affected either by tumor aging or by treatment with TNF. This study shows that in vivo estimates of tissue protein metabolism based on our [14C]leucine constant infusion model closely reflect the growth characteristic of that tissue. A cytotoxic perfusion-independent effect for intravenous TNF on growing tumor tissue is demonstrable as increased protein breakdown. Furthermore, the commonly used concept of whole body protein metabolism, derived solely from tracer dilution in plasma, is an oversimplification.

scholarly journals Processing of the precursor to a chloroplast ribosomal protein made in the cytosol occurs in two steps, one of which depends on a protein made in the chloroplast.

1985 ◽  
Vol 5 (5) ◽  
pp. 1093-1099 ◽  
Author(s):  
R J Schmidt ◽  
N W Gillham ◽  
J E Boynton
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Apparent Molecular Weight ◽  
Protein L ◽  
Mature Form ◽  
Chloroplast Protein Synthesis ◽  
Made In

In pulse-chase experiments in which log-phase cells of Chlamydomonas reinhardtii were labeled in vivo for 5 min with H2(35)SO4, fluorographs of immunoprecipitates from whole cell extracts revealed that chloroplast ribosomal proteins L-2, L-6, L-21, and L-29, which are made in the cytosol and imported, appeared in their mature forms. However, in the case of chloroplast ribosomal protein L-18, which is also made in the cytoplasm and imported, a prominent precursor with an apparent molecular weight of 17,000 was found at the end of a 5-min pulse. This precursor was processed to its mature size (apparent molecular weight of 15,500) within the first 5 min of the subsequent chase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the precursor to L-18 formed in vivo was 1.5 kilodaltons smaller than the primary product detected in translations of Chlamydomonas polyadenylated RNA in vitro. Upon a 10-min incubation with a postribosomal supernatant from Chlamydomonas, the 18,500-dalton precursor detected in vitro could be partially converted into a polypeptide that comigrated with the 17,000-dalton precursor detected in extracts of cells labeled in vivo. Under conditions in which the total amounts of chloroplast proteins had been reduced and cells were made to synthesize ribosomes rapidly, the apparent half-life of the 17,000-dalton precursor was extended over that seen in log-phase cells. When chloroplast protein synthesis was inhibited with lincomycin for 3 h before labeling under these conditions, the 17,000-dalton L-18 precursor but not the mature form was found, and the precursor was slowly degraded during a 60-min chase. When cells were placed in the dark for 3 h before labeling, processing of this precursor to the mature form appeared unaffected, but the chloroplast-synthesized ribosomal protein L-26 was detected, indicating that chloroplast protein synthesis was still occurring. We interpret these results to indicate that the maturation of protein L-18 in vivo involves at least two processing steps, one of which depends on a protein made on chloroplast ribosomes.

scholarly journals Cell type-specific control of protein synthesis and proliferation by FGF-dependent signaling to the translation repressor 4E-BP

2016 ◽  
Vol 113 (27) ◽  
pp. 7545-7550 ◽  
Author(s):  
Rachel Ruoff ◽  
Olga Katsara ◽  
Victoria Kolupaeva
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Bone Development ◽  
Binding Protein ◽  
Initiation Factor ◽  
Start Codon ◽  
Dependent Manner ◽  
Fgf Signaling ◽  
Cell Type

Regulation of protein synthesis plays a vital role in posttranscriptional modulation of gene expression. Translational control most commonly targets the initiation of protein synthesis: loading 40S ribosome complexes onto mRNA and AUG start codon recognition. This step is initiated by eukaryotic initiation factor 4E (eIF4E) (the m7GTP cap-binding protein), whose binding to eIF4G (a scaffolding subunit) and eIF4A (an ATP-dependent RNA helicase) leads to assembly of active eIF4F complex. The ability of eIF4E to recognize the cap is prevented by its binding to eIF4E binding protein (4E-BP), which thereby inhibits cap-dependent translation by sequestering eIF4E. The 4E-BP activity is, in turn, inhibited by mTORC1 [mTOR (the mechanistic target of rapamycin) complex 1] mediated phosphorylation. Here, we define a previously unidentified mechanism of mTOR-independent 4E-BP1 regulation that is used by chondrocytes upon FGF signaling. Chondrocytes are responsible for the formation of the skeleton long bones. Unlike the majority of cell types where FGF signaling triggers proliferation, chondrocytes respond to FGF with inhibition. We establish that FGF specifically suppresses protein synthesis in chondrocytes, but not in any other cells of mesenchymal origin. Furthermore, 4E-BP1 repressor activity is necessary not only for suppression of protein synthesis, but also for FGF-induced cell-cycle arrest. Importantly, FGF-induced changes in the 4E-BP1 activity observed in cell culture are likewise detected in vivo and reflect the action of FGF signaling on downstream targets during bone development. Thus, our findings demonstrate that FGF signaling differentially impacts protein synthesis through either stimulation or repression, in a cell-type–dependent manner, with 4E-BP1 being a key player.

scholarly journals Effects of testosterone on messenger ribonucleic acid and protein synthesis in rat seminal vesicle

1978 ◽  
Vol 174 (2) ◽  
pp. 543-551 ◽  
Author(s):  
Stephen J. Higgins ◽  
Joy M. Burchell
Keyword(s):  
Protein Synthesis ◽  
Seminal Vesicle ◽  
Steroid Hormones ◽  
Secretory Proteins ◽  
Total Acid ◽  
Free System ◽  
Messenger Ribonucleic Acid ◽  
Mrna Population ◽  
Rat Seminal Vesicle

In a previous report [Higgins et al. (1976) Biochem. J.158, 271–282] we described the effects of alterations in androgen status on the synthesis of two basic secretory proteins of the rat seminal vesicle. In the present paper we examine the effects of testosterone on the activity of mRNA in the seminal vesicle. Total cellular poly(A)-rich RNA was isolated and translated in a cell-free system prepared from wheat germ. Translation products were separated on denaturing polyacrylamide gels and the protein bands corresponding to the two basic secretory proteins were identified immunologically. Incorporation of radioactive methionine into these bands was taken as a measure of the individual mRNA activities. Total mRNA activity was estimated by radioactivity in total acid-precipitable material. The results show that 1 to 2 weeks after castration the activities of mRNA molecules for the basic secretory proteins were decreased 10–20-fold on a tissue basis. Testosterone given in vivo rapidly and substantially restores mRNA activity to normal. Since these changes correlate closely with variations in the rates of synthesis of the secretory proteins in whole cells it suggests that androgenic steroids control protein synthesis chiefly via mRNA availability. In this respect their action resembles those of other steroid hormones acting in other systems. However, these effects of testosterone on the mRNA molecules for the major secretory proteins could not be distinguished from those on total mRNA. Thus the proportion of the total mRNA population accounted for by the two specific mRNA molecules showed less than a 2-fold variation with androgen status. Similarly the two secretory proteins always accounted for 25–33% of general protein synthesis. This is in sharp contrast with the markedly differential effects of other steroid hormones controlling synthesis of major proteins in other well-studied systems. We interpret our results as indicating that testosterone regulates the mRNA population of the seminal vesicle as a whole.

Preliminary 'in vivo' measurements of protein and energy metabolism in the skin of sheep

1989 ◽  
Vol 40 (4) ◽  
pp. 879 ◽  
Author(s):  
PM Harris ◽  
DW Dellow ◽  
BR Sinclair
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Acid Metabolism ◽  
Significant Proportion ◽  
Whole Body ◽  
Oxygen Utilization ◽  
Body Protein ◽  
Discrete Area ◽  
Made In

An arterio-venous preparation was developed which allowed infusion into, and/or sampling from, branches of the deep circumflex iliac artery and vein supplying and draining a discrete area of skin on the abdominal flank of Romney sheep.Measurements of blood flow (using dye dilution techniques), utilization or output of energy metabolites (oxygen, glucose, lactate and acetate) and amino acid metabolism were made in relation to whole body protein and energy metabolism.Measurements on the patch suggested that blood flow to the total skin was about 6% of cardiac output but that only 1-2% of whole body oxygen utilization occurred in the skin. This was partly accounted for by a significant proportion of glucose uptake (1.15 g day-1) being anaerobically oxidized to lactate (0.41 g day-1). Measurements of protein synthesis in the patch showed that between 10 and 16% of whole body protein synthesis occurs in the skin.Results from the preparation demonstrate that it is a useful procedure to study metabolism in a defined patch of skin in the intact animal.

Yolk Protein Synthesis in the Ovary of Octopus Vulgaris and its Control by the Optic Gland Gonadotropin

1973 ◽  
Vol 59 (3) ◽  
pp. 665-674
Author(s):  
R. K. O'DOR ◽  
M. J. WELLS
Keyword(s):  
Protein Synthesis ◽  
High Rate ◽  
Follicle Cells ◽  
Blood Protein ◽  
Octopus Vulgaris ◽  
Yolk Proteins ◽  
Stage Of Development ◽  
Rapid Accumulation ◽  
A Site

1. Over 98% of a dose of [14C]leucine injected into the circulation of Octopus vulgaris is removed from the blood during the first hour. 2. There is a rapid accumulation of labelled protein in the ovaries of maturing animals within 2 h of injection. Within 5-7 h the ovaries contain nearly 40% of the injected label in protein form. 3. Removal of the optic glands prevents this accumulation of protein. 4. There is little labelled protein in the livers of either control or maturing animals at any time; but a slow, steady accumulation occurs in their blood. 5. The level of labelled protein appearing in the blood of acutely ovariectomized, maturing females is no higher than in controls; and when blood protein from ovariectomized animals is injected into normal maturing females it is not taken up by the ovaries. 6. The labelled protein which accumulates in the blood is probably haemocyanin. Preliminary experiments indicate that the branchial glands, which are already believed to be a site of haemocyanin synthesis on morphological grounds, show a high rate of protein synthesis and release. 7. Isolated ovarian follicles in a liquid medium synthesize protein at a rate somewhat lower, but comparable with, the apparent in vivo rate. 8. The combined evidence from these experiments indicates that in Octopus yolk proteins are formed within the ovary-probably by the follicle cells-rather than being synthesized elsewhere and transported through the blood, as in arthropods and vertebrates. 9. The optic gland gonadotropin is essential for maintenance of protein synthesis during secondary vitellogenesis and the follicle cells are a likely site for its action during this stage of development.

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