scholarly journals Poly(A) tail shortening is the translation-dependent step in c-myc mRNA degradation.

1990 ◽  
Vol 10 (12) ◽  
pp. 6132-6140 ◽  
Author(s):  
I A Laird-Offringa ◽  
C L de Wit ◽  
P Elfferich ◽  
A J van der Eb
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
Degradation Pathway ◽  
Mrna Degradation ◽  
The Body ◽  
Second Step ◽  
Protein Synthesis Inhibitors ◽  
Rapid Degradation ◽  
Translation Block ◽  
Insight Into

The highly unstable c-myc mRNA has been shown to be stabilized in cells treated with protein synthesis inhibitors. We have studied this phenomenon in an effort to gain more insight into the degradation pathway of this mRNA. Our results indicate that the stabilization of c-myc mRNA in the absence of translation can be fully explained by the inhibition of translation-dependent poly(A) tail shortening. This view is based on the following observations. First, the normally rapid shortening of the c-myc poly(A) tail was slowed down by a translation block. Second, c-myc messengers which carry a short poly(A) tail, as a result of prolonged actinomycin D or 3'-deoxyadenosine treatment, were not stabilized by the inhibition of translation. We propose that c-myc mRNA degradation proceeds in at least two steps. The first step is the shortening of long poly(A) tails. This step requires ongoing translation and thus is responsible for the delay in mRNA degradation observed in the presence of protein synthesis inhibitors. The second step involves rapid degradation of the body of the mRNA, possibly preceded by the removal of the short remainder of the poly(A) tail. This last step is independent of translation.

Poly(A) tail shortening is the translation-dependent step in c-myc mRNA degradation

1990 ◽  
Vol 10 (12) ◽  
pp. 6132-6140
Author(s):  
I A Laird-Offringa ◽  
C L de Wit ◽  
P Elfferich ◽  
A J van der Eb
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
Degradation Pathway ◽  
Mrna Degradation ◽  
The Body ◽  
Second Step ◽  
Protein Synthesis Inhibitors ◽  
Rapid Degradation ◽  
Translation Block ◽  
Insight Into

The highly unstable c-myc mRNA has been shown to be stabilized in cells treated with protein synthesis inhibitors. We have studied this phenomenon in an effort to gain more insight into the degradation pathway of this mRNA. Our results indicate that the stabilization of c-myc mRNA in the absence of translation can be fully explained by the inhibition of translation-dependent poly(A) tail shortening. This view is based on the following observations. First, the normally rapid shortening of the c-myc poly(A) tail was slowed down by a translation block. Second, c-myc messengers which carry a short poly(A) tail, as a result of prolonged actinomycin D or 3'-deoxyadenosine treatment, were not stabilized by the inhibition of translation. We propose that c-myc mRNA degradation proceeds in at least two steps. The first step is the shortening of long poly(A) tails. This step requires ongoing translation and thus is responsible for the delay in mRNA degradation observed in the presence of protein synthesis inhibitors. The second step involves rapid degradation of the body of the mRNA, possibly preceded by the removal of the short remainder of the poly(A) tail. This last step is independent of translation.

Inhibition of protein synthesis does not block myocardial protection afforded by preconditioning

1990 ◽  
Vol 259 (6) ◽  
pp. H1822-H1825 ◽  
Author(s):  
J. Thornton ◽  
S. Striplin ◽  
G. S. Liu ◽  
A. Swafford ◽  
A. W. Stanley ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Coronary Occlusion ◽  
Actinomycin D ◽  
Protein Synthesis Inhibitors ◽  
Group 4 ◽  
Ischemic Period ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

It is currently unknown how preconditioning the heart with brief periods of ischemia makes it resistant to infarction from a subsequent ischemic insult. The protein synthesis inhibitors, cycloheximide and actinomycin D, were used to determine whether preconditioning involves synthesis of a protective protein. Ischemia was produced by occlusion of a branch of the left coronary artery in open-chest anesthetized rabbits. All groups were subjected to 30 min of ischemia followed by 3 h of reperfusion. The first two groups served as noninhibited controls. Group 1 was subjected to ischemia with no preconditioning. Group 2 was preconditioned with two 5-min ischemic periods each followed by 10 min of reperfusion, before the 30-min ischemic period. Groups 3 and 4 were the same as groups 1 and 2, respectively, except that cycloheximide was administered before coronary occlusion. Groups 5 and 6 were also the same as groups 1 and 2 except that actinomycin D was administered before coronary occlusion. After 3 h of reperfusion all hearts were removed and the size of the ischemic zone and infarct were determined. The percent of the ischemic zone infarcted was small and similar in all preconditioned groups (3.3 +/- 1.1% for group 2, 7.4 +/- 3.3% for group 4, and 0.5 +/- 0.7% for group 6). All nonpreconditioned groups had large infarcts with no differences between groups (39.0 +/- 8.5% for group 1, 31.6 +/- 6.3% for group 3, 30.8 +/- 5.9% for group 5). Because neither cycloheximide nor actinomycin D could block protection afforded by preconditioning, it seems unlikely that synthesis of a protective protein is the mechanism of protection.

THE DEVELOPMENT OF AN IN VITRO SYSTEM FOR ESTIMATING OXYTOCINASE IN THE RABBIT HYPOTHALAMUS AND THE EFFECTS OF SOME PROTEIN SYNTHESIS INHIBITORS AND OESTRADIOL-17β ON ENZYME ACTIVITY

1974 ◽  
Vol 75 (3) ◽  
pp. 443-451 ◽  
Author(s):  
Dona A. Frith ◽  
K. C. Hooper
Keyword(s):  
Protein Synthesis ◽  
Enzyme Activity ◽  
Steroid Hormones ◽  
Actinomycin D ◽  
Protein Synthesis Inhibitors ◽  
In Vitro System

ABSTRACT An in vitro system for investigating the effects of steroid hormones and protein synthesis inhibitors on hypothalamic peptidases inactivating oxytocin has been developed. In the presence of oestradiol-17β enzyme activity was increased in the in vitro system whilst this increase was blocked completely by cycloheximide and partially blocked by actinomycin-D. It is apparent therefore that oestradiol-17β acts directly on the hypothalamus stimulating oxytocinase activity.

EFFECTS OF PROTEIN SYNTHESIS INHIBITORS ON ANGIOTENSIN-STIMULATED AND ANGIOTENSIN-INHIBITED FLUID TRANSPORT BY RAT JEJUNUM IN VIVO

1977 ◽  
Vol 74 (2) ◽  
pp. 213-221 ◽  
Author(s):  
JENNIFER E. BOLTON ◽  
K. A. MUNDAY ◽  
B. J. PARSONS
Keyword(s):  
Protein Synthesis ◽  
Fluid Transport ◽  
Actinomycin D ◽  
Inhibitory Response ◽  
Rat Jejunum ◽  
Protein Synthesis Inhibitors ◽  
Translation Stage ◽  
High Doses ◽  
Stimulation Of

A study has been made of the effects of protein synthesis inhibitors on the responses of rat jejunum in vivo to intravenous infusions of angiotensin. Actinomycin D, an inhibitor of the transcription stage of protein synthesis, was without effect on the stimulation of fluid transport which follows the infusion of low doses of angiotensin. Cycloheximide, an inhibitor of the translation stage of protein synthesis, blocked the stimulatory response to angiotensin, but was without effect on the inhibitory response to high doses of the hormone. It is concluded that low (physiological) doses of angiotensin stimulate fluid transport by a mechanism involving protein synthesis at a stage later than transcription whereas high doses of the hormone inhibit fluid transport by a process which does not require protein synthesis.

scholarly journals Abundance of hepatic metallothionein mRNA is increased by protein-synthesis inhibitors. Evidence for transcriptional activation and post-transcriptional regulation

1991 ◽  
Vol 273 (1) ◽  
pp. 185-188 ◽  
Author(s):  
C C McCormick ◽  
L M Salati ◽  
A G Goodridge
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Transcriptional Regulation ◽  
Transcriptional Activation ◽  
Actinomycin D ◽  
Protein Synthesis Inhibitors ◽  
Mrna Accumulation ◽  
Hepatic Metallothionein ◽  
Post Transcriptional Regulation

Ongoing protein synthesis is a prerequisite in the expression of some genes. We studied the effect of various protein synthesis inhibitors on the expression of the avian metallothionein (MT) gene. Chicken embryonic hepatocytes in culture were exposed to various concentrations of cycloheximide, puromycin and pactamycin. At concentrations which decreased total protein synthesis by about 90% each inhibitor increased MT mRNA accumulation approx. 5-fold at 9 h of incubation. Incubation with puromycin or zinc for 2 h markedly increased the rate of MT gene transcription. Estimates of the half-life of MT mRNA by using actinomycin D suggested for cycloheximide, but not puromycin, decreased the decay rate of MT mRNA. These data suggest the potential for post-transcriptional regulation of the avian MT gene. We conclude that different antibiotics increase the accumulation of hepatocyte MT mRNA by different mechanisms and that the possibility of multiple mechanisms should be considered in other studies of the role of protein synthesis in gene expression.

scholarly journals The breakdown of Tetrahymena ribosomes in vivo. The effects of inhibitors

1982 ◽  
Vol 208 (3) ◽  
pp. 831-837 ◽  
Author(s):  
H G Klemperer ◽  
D J Pilley
Keyword(s):  
Protein Synthesis ◽  
Energy Metabolism ◽  
Ribosomal Rna ◽  
Lysosomal Enzymes ◽  
Actinomycin D ◽  
Degradation Mechanism ◽  
Protein Synthesis Inhibitors ◽  
Total Rna

1. When Tetrahymena were deprived of nutrients 50% of the polysomes disaggregated within 20 min and 20% of the total RNA broke down in 2 h. Ribosomal RNA accounted for 75% of the RNA breakdown. 2. RNA labelled by a long incubation with [14C]uridine was stable in growing cells and in the presence of actinomycin D, but broke down at the same rate as bulk RNA in starved cells. 3. The following substances inhibited the loss of RNA during starvation: cycloheximide (which inhibited both polysome disaggregation and protein synthesis), inhibitors of energy metabolism and puromycin (all of which caused polysome disaggregation and inhibited protein synthesis), and chloroquine and 7-amino-1-chloro-3-L-tosylamidoheptan-2-one (‘TLCK’) (neither of which affected polysomes or protein synthesis). 4. Starvation appears to activate a ribosome degradation mechanism that may involve lysosomal and non-lysosomal enzymes.

scholarly journals Stimulation of Monocyte Procoagulant Activity by Adherence to Different Surfaces

1977 ◽  
Author(s):  
C.J.W. van Ginkel ◽  
J.I.H. Oh ◽  
W.G. van Aken ◽  
J. Vreeken
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
Procoagulant Activity ◽  
Adherent Cells ◽  
Protein Synthesis Inhibitors ◽  
Mononuclear Leukocyte ◽  
Thromboplastic Activity ◽  
Recalcification Time ◽  
Monocyte Adherence ◽  
Stimulation Of

When mononuclear leukocyte suspensions (5.109 cells/1, 25% monocytes) were incubated on glass dishes, 57 ± 1% of the monocytes were found to adhere to the surface after 3.5 h incubation at 37°C. It was found that the adherent cells shortened the recalcification time from 435 ± 35 to 50 + 2 sec using normal plasma as substrate. However, when monocyte adherence was prevented by incubating the leukocytes on cuprophane (3 + 1% adherence), much less PCA was detectable (the recalcification time was shortened from 435 ± 35 to 201 ± 19 sec). After exposing to glass the non-adherent monocytes had negligible PCA in comparison to the adherent monocytes. Protein synthesis inhibitors (cycloheximide and actinomycin D) inhibited PCA generation but did not affect monocyte adherence. These data provide the first evidence that adherence of monocytes is a stimulus for the generation of thromboplastic activity.

scholarly journals Transient arrest in proteasomal degradation during inhibition of translation in the unfolded protein response

2007 ◽  
Vol 404 (3) ◽  
pp. 509-516 ◽  
Author(s):  
Marina Shenkman ◽  
Sandra Tolchinsky ◽  
Maria Kondratyev ◽  
Gerardo Z. Lederkremer
Keyword(s):  
Protein Synthesis ◽  
Unfolded Protein Response ◽  
Proteasomal Degradation ◽  
Protein Synthesis Inhibitors ◽  
Translation Arrest ◽  
Unfolded Protein ◽  
Cycle Arrest ◽  
Translation Block ◽  
The Unfolded Protein Response ◽  
Protein Response

The UPR (unfolded protein response) activates transcription of genes involved in proteasomal degradation. However, we found that in its early stages the UPR leads to a transient inhibition of proteasomal disposal of cytosolic substrates (p53 and p27kip1) and of those targeted to ER (endoplasmic reticulum)-associated degradation (uncleaved precursor of asialoglycoprotein receptor H2a). Degradation resumed soon after the protein synthesis arrest that occurs in early UPR subsided. Consistent with this, protein synthesis inhibitors blocked ubiquitin/proteasomal degradation. Ubiquitination was inhibited during the translation block, suggesting short-lived E3 ubiquitin ligases as candidate depleted proteins. This was indeed the case for p53 whose E3 ligase, Mdm2 (murine double minute 2), when overexpressed, restored the degradation, whereas a mutant Mdm2 in its acidic domain restored the ubiquitination but did not completely restore the degradation. Inhibition of proteasomal degradation early in UPR may prevent depletion of essential short-lived factors during the translation arrest. Stabilization of p27 through this mechanism may explain the cell cycle arrest in G1 when translation is blocked by inhibitors or by the UPR.

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