scholarly journals ON THE DIFFERENTIAL CYTOTOXICITY OF ACTINOMYCIN D

1971 ◽  
Vol 50 (3) ◽  
pp. 746-761 ◽  
Author(s):  
Stanley G. Sawicki ◽  
Gabriel C. Godman
Keyword(s):  
Protein Synthesis ◽  
Acute Phase ◽  
Hela Cells ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Differential Susceptibility ◽  
Cell Types ◽  
Cell Degeneration ◽  
L Cells ◽  
Inhibition Of Protein Synthesis

Actinomycin D (AMD) at concentrations that inhibit cellular RNA synthesis by 85% or more causes an acute phase of lethal cell degeneration in HeLa cultures beginning as early as 3 hr after drug exposure, resulting in the nearly complete loss of viable cells by 12 hr. The loss of cells during this acute phase of lethality is closely dose dependent. Vero, WI38, or L cells are not susceptible to this early acute cyto-intoxication by AMD, and may begin to die only after 1–2 days. Differential susceptibility to acute cyto-intoxication by AMD, or other inhibitors of RNA synthesis (daunomycin or nogalamycin), among different types of cultured cells is analogous to that observed in vivo in certain tissues and tumors, and cannot be accounted for by differences in the effect of AMD on RNA, DNA, or protein syntheses, or by the over-all loss of preformed RNA. Actinomycin D in a dose that inhibits RNA synthesis causes an equivalent loss of the prelabeled RNA in all the cell types studied. Inhibition of protein synthesis with streptovitacin A or of DNA synthesis with hydroxyurea does not cause acute lethal injury in HeLa cells as does inhibition of RNA synthesis. Furthermore, since Vero or L cells divide at about the same rate as HeLa cells, no correlation can be drawn between the rate of cell proliferation and susceptibility to the cytotoxicity of AMD. Susceptibile cells are most vulnerable to intoxication by AMD in the G1-S interphase or early S phase. Inhibition of protein synthesis (which protects cells against damage by other agents affecting DNA) does not protect against AMD-induced injury. Although HeLa cells bind more AMD at a given dose than Vero or L cells, the latter cell types, given higher doses, can be made to bind proportionally more AMD without succumbing to acute cyto-intoxication. It is suggested that the differential susceptibility of these cell types to acute poisoning by AMD may reflect differences among various cells in the function or stability of certain RNA species not directly involved in translation whose presence is vital to cells. In HeLa cells, these critical species of RNA are presumed to have a short half-life.

scholarly journals A comparative study of the effect of aflatoxin B1 and actinomycin D on HeLa cells

1969 ◽  
Vol 114 (2) ◽  
pp. 289-298 ◽  
Author(s):  
E. H. Harley ◽  
K. R. Rees ◽  
A. Cohen
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Mechanism Of Action ◽  
Aflatoxin B1 ◽  
Hela Cells ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Inhibitory Effect ◽  
Cytotoxic Effects ◽  
Rna Precursor

1. The cytotoxic effects of aflatoxin B1 on HeLa cells were examined and effects of short exposures of the cells to the toxin were found to be reversible. 2. Aflatoxin B1 inhibited the synthesis of both ribosomal and heterodisperse RNA. It is proposed that the toxin's mechanism of action on ribosomal RNA synthesis is related to its inhibitory effect on the maturation of the 45s-ribosomal-RNA precursor. 3. Protein synthesis is inhibited to a greater extent by aflatoxin B1 than by actinomycin D. In contrast with actinomycin D, aflatoxin B1 was shown to disaggregate polyribosomes directly.

scholarly journals ON THE RECOVERY OF TRANSCRIPTION AFTER INHIBITION BY ACTINOMYCIN D

1972 ◽  
Vol 55 (2) ◽  
pp. 299-309 ◽  
Author(s):  
Stanley G. Sawicki ◽  
Gabriel C. Godman
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Cell Types ◽  
Vero Cells ◽  
Sufficient Condition ◽  
Long Period ◽  
Different Cell Types ◽  
Early Restoration

After pulse exposure to concentrations of actinomycin D (AMD) sufficient to abolish transcription, Vero cells recover RNA synthesis much more rapidly than most other cell types. This is only in part attributable to the remarkable capacity of Vero very promptly to excrete bound AMD, elimination of which, although necessary, is not a sufficient condition for resurgence of RNA synthesis. After elimination of higher concentrations of AMD from Vero, although over-all RNA synthesis resumes a normal rate within 24 hr, protein synthesis lags, and a long period of division-delay ensues. Division-delay lasting 2–3 days results from exposure of Vero to doses of AMD greater than those that suppress RNA synthesis by greater than 90% (e.g. 1 µg/ml for 2 hr) but not by lower doses, which permit almost immediate reentry into the cell cycle. In contrast, although L cells recover over-all RNA synthesis very slowly after pulse treatment with AMD, resumption of protein synthesis or cell division is not comparably delayed thereafter. These and other data suggest that the early restoration of RNA synthesis in Vero after relief of inhibition by AMD is qualitatively imperfect. The results reported herein are explainable by the hypothesis that the synthesis of those species of RNA which are involved, directly or indirectly, in reactivating the transcription of genes controlling progression in the cell cycle is relatively resistant to suppression by AMD. Decay of such RNA templates and their products, which differs in different cell types during inhibition by AMD, determines the duration of division-delay.

Stabilization of tubulin mRNA by inhibition of protein synthesis in sea urchin embryos

1988 ◽  
Vol 8 (8) ◽  
pp. 3518-3525
Author(s):  
Z Y Gong ◽  
B P Brandhorst
Keyword(s):  
Protein Synthesis ◽  
Sea Urchin ◽  
Mrna Stability ◽  
Rna Synthesis ◽  
Rapid Loss ◽  
Transcription Analysis ◽  
Inhibition Of Protein Synthesis ◽  
Tubulin Mrna ◽  
Autogenous Regulation

An increased level of unpolymerized tubulin caused by depolymerization of microtubules in sea urchin larvae resulted in a rapid loss of tubulin mRNA, which was prevented by nearly complete inhibition of protein synthesis. Results of an RNA run-on assay indicated that inhibition of protein synthesis does not alter tubulin gene transcription. Analysis of the decay of tubulin mRNA in embryos in which RNA synthesis was inhibited by actinomycin D indicated that inhibition of protein synthesis prevents the destabilization of tubulin mRNA. The effect was similar whether mRNA was maintained on polysomes in the presence of emetine or anisomycin or displaced from the polysomes in the presence of puromycin or pactamycin; thus, the stabilization of tubulin mRNA is not dependent on the state of the polysomes after inhibition of protein synthesis. Even after tubulin mRNA declined to a low level after depolymerization of microtubules, it could be rescued by treatment of embryos with inhibitors of protein synthesis. Tubulin mRNA could be induced to accumulate prematurely in gastrulae but not in plutei if protein synthesis was inhibited, an observation that is indicative of the importance of the autogenous regulation of tubulin mRNA stability during embryogenesis. Possible explanations for the role of protein synthesis in the control of mRNA stability are discussed.

Conditions necessary for inhibition of protein synthesis and production of cytopathic effect in Aedes albopictus cells infected with vesicular stomatitis virus

1982 ◽  
Vol 2 (1) ◽  
pp. 66-75
Author(s):  
S Gillies ◽  
V Stollar
Keyword(s):  
Protein Synthesis ◽  
Vesicular Stomatitis Virus ◽  
Aedes Albopictus ◽  
Rna Synthesis ◽  
Cytopathic Effect ◽  
Viral Gene ◽  
Inhibition Of Protein Synthesis ◽  
Infected Cells ◽  
Vesicular Stomatitis ◽  
Aedes Albopictus Cells

The relationship between the development of cytopathic effect (CPE) and the inhibition of host macromolecular synthesis was examined in a CPE-susceptible cloned line of Aedes albopictus cells after infection with vesicular stomatitis virus. To induce rapid and maximal CPE, two conditions were required: (i) presence of serum in the medium and (ii) incubation at 34 degrees C rather than at 28 degrees C. In the absence of serum, incubation of infected cultures at 34 degrees C resulted in a significant increase in viral protein and RNA synthesis compared with that observed at 28 degrees C. However, when serum was present in the medium, by 6 h after infection protein synthesis (both host and viral) was markedly inhibited when infected cells were maintained at 34 degrees C. RNA synthesis (host and viral) was also inhibited in vesicular stomatitis virus-infected cells maintained at 34 degrees C with serum, but somewhat more slowly than protein synthesis. Examination of polysome patterns indicated that when infected cultures were maintained under conditions which predispose to CPE, more than half of the ribosomes existed as monosomes, suggesting that protein synthesis was being inhibited at the level of initiation. In addition, the phosphorylation of one (or two) polysome-associated proteins was reduced when protein synthesis was inhibited. Our findings indicate a strong correlation between virus-induced CPE in the LT-C7 clone of A. albopictus cells and the inhibition of protein synthesis. Although the mechanism of the serum effect is not understood, incubation at 34 degrees C probably predisposes to CPE and inhibition of protein synthesis by increasing the amount of viral gene products made.

scholarly journals Stabilization of tubulin mRNA by inhibition of protein synthesis in sea urchin embryos.

1988 ◽  
Vol 8 (8) ◽  
pp. 3518-3525 ◽  
Author(s):  
Z Y Gong ◽  
B P Brandhorst
Keyword(s):  
Protein Synthesis ◽  
Sea Urchin ◽  
Mrna Stability ◽  
Rna Synthesis ◽  
Rapid Loss ◽  
Transcription Analysis ◽  
Inhibition Of Protein Synthesis ◽  
Tubulin Mrna ◽  
Autogenous Regulation

An increased level of unpolymerized tubulin caused by depolymerization of microtubules in sea urchin larvae resulted in a rapid loss of tubulin mRNA, which was prevented by nearly complete inhibition of protein synthesis. Results of an RNA run-on assay indicated that inhibition of protein synthesis does not alter tubulin gene transcription. Analysis of the decay of tubulin mRNA in embryos in which RNA synthesis was inhibited by actinomycin D indicated that inhibition of protein synthesis prevents the destabilization of tubulin mRNA. The effect was similar whether mRNA was maintained on polysomes in the presence of emetine or anisomycin or displaced from the polysomes in the presence of puromycin or pactamycin; thus, the stabilization of tubulin mRNA is not dependent on the state of the polysomes after inhibition of protein synthesis. Even after tubulin mRNA declined to a low level after depolymerization of microtubules, it could be rescued by treatment of embryos with inhibitors of protein synthesis. Tubulin mRNA could be induced to accumulate prematurely in gastrulae but not in plutei if protein synthesis was inhibited, an observation that is indicative of the importance of the autogenous regulation of tubulin mRNA stability during embryogenesis. Possible explanations for the role of protein synthesis in the control of mRNA stability are discussed.

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