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Effects of cycloheximide and 5-fluorouracil on formation of low-molecular-weight ribonucleic acid in yeast.

The effects of cycloheximide and 5-fluorouracil on the formation of low-molecular-weight ribonucleic acid (RNA) in yeast were investigated. Both compounds were found to affect the synthesis of low-molecular-weight RNA of ribosomal origin more than transfer RNA but less than the high-molecular-weight ribosomal RNA. 5-Fluorouracil-containing transfer RNA was separated from normal transfer RNA by chromatography on diethylaminoethyl cellulose at 80 C in the presence of 7 m urea.

Adenine↗

Synthesis of type 2 adenovirus DNA in the presence of cycloheximide.

Adenovirus type 2 DNA synthesis, either in permissive human cells or nonpermissive monkey cells, becomes independent of protein synthesis after the appearance of progeny viral DNA. In the presence of cycloheximide, semiconservative replication and initiation of progeny molecules can occur.

Adenoviridae↗

Cycloheximide induction of xenotropic type C virus from synchronized mouse cells: metabolic requirements for virus activation.

The information for type C RNA viruses is genetically transmitted within the cellular DNA of the normal mouse cell. These viruses can be induced after exposure of cells to two classes of chemicals, inhibitors of protein synthesis and halogenated pyrimidines. The metabolic requirements for activation of one endogenous virus of BALB/c mouse cells by representatives of each class of drugs were studies. Cycloheximide and iododeoxyuridine each induce virus efficiently from cultures in exponential growth but are inactive on cells in stationary phase. However, cells are maximally sensitive to the actions of each drug at different times within the cell cycle. Further, virus induction in response to each is differentially inhibited under conditions of simultaneous cell exposure to inhibitors of DNA or RNA synthesis. The results provide support for the concept that inhibitors of protein synthesis and halogenated pyrimidines act by different mechanisms to induce type C virus release.

Animals↗

Detection of adenovirus type 2-induced early polypeptides using cycloheximide pretreatment to enhance viral protein synthesis.

(35S) methionine-labeled polypeptides synthesized by adenovirus type 2-infected cells have been analyzed by polyacrylamide gradient gel electrophoresis and autoradiography. Cycloheximide (CH) was added to infected cultures to accumulate early viral mRNA relative to host cell mRNA. This allowed viral proteins to be synthesized in increased amounts relative to host proteins after removal of CH and pulse-labeling with (35S)methionine. During the labeling period arabinosyl cytosine was added to prevent the synthesis of late viral proteins. This procedure facilitated the detection of six early viral-induced polypeptides, designated EP1 through EP6 (early protein), with apparent molecular weights of 75,000 (75K), 42K, 21K, 18K, 15K, and 11K. Supportive data were obtained by coelectrophoresis of (35S)- and (3H)methionine-labeled polypeptides from infected and uninfected cells, respectively. Three of these early polypeptides have not been previously reported. CH pretreatment enhanced the rates of synthesis of EP4 and EP6 20- to 30-fold and enhanced that of the others approximately twofold. The maximal rates of synthesis of the virus-induced proteins varied, in a different manner, with time postinfection and CH pretreatment. Since CH pretreatment appears to increase the levels of early viral proteins, it may be a useful procedure to assist their isolation and functional characterization.

Adenoviridae↗

Herpes simplex virus thymidine kinase transcripts are absent from both nucleus and cytoplasm during infection in the presence of cycloheximide.

Nick-translated DNA from a recombinant plasmid containing the herpes simplex virus type 1 thymidine kinase gene was used as a probe for the synthesis of thymidine kinase RNA. The recombinant plasmid was generated by inserting the 3.5-kilobase fragment derived by BamHI digestion of herpes simplex virus type 1 DNA into plasmid pBR322. At 8 h after infection, cytoplasmic and nuclear RNA hybridized to 14% and 19% of the recombinant DNA probe, respectively. However, no significant hybridization was found with either nuclear or cytoplasmic RNA extracted from cells infected and maintained in the presence of cycloheximide. This suggests that no thymidine kinase-related RNA was synthesized in the absence of alpha polypeptides, and supports the hypothesis that the alpha polypeptides effect new thymidine kinase RNA synthesis rather than being involved in processing or transport of thymidine kinase RNA. In cells infected and maintained in the presence of the arginine analog canavanine, about 2 to 3% of the plasmid DNA was found to hybridize with cytoplasmic and nuclear RNA. However, when a recombinant plasmid DNA containing only thymidine kinase coding sequences was used, no significant hybridization was found. The inhibition of thymidine kinase transcription by canavanine suggests that thymidine kinase belongs to the beta 2 kinetic class.

Canavanine↗

Cytoplasmic viral DNA synthesis in exogenous infection of murine leukemia virus: effect of interferon and cycloheximide.

Cytoplasmic viral DNA synthesis can be followed efficiently by [3H]thymidine labeling of cells exogenously infected with Moloney murine leukemia virus. Both the negative and the positive strands of viral DNA reached their maximal level in the cytoplasm at 3.5 h postinfection. Interferon treatment before infection markedly reduced the amount of viral DNA formed during the first 3.5 h, but led to a second major wave of viral DNA synthesis, peaking at 7.5 h postinfection. No such late cytoplasmic DNA synthesis occurred in the untreated control. Inhibition of protein synthesis by cycloheximide, on the other hand, stimulated cytoplasmic viral DNA synthesis during the first 3.5 h.

Animals↗

Membrane binding of input arbovirus ribonucleic acid: effect of interferon or cycloheximide.

By 1 hr after infection, 36% of input Semliki Forest virus ribonucleic acid (RNA) which was cell associated was found in a membrane structure. This structure had many similarities to the membrane-associated replication complex (MRC) which had previously been identified in arbovirus infections. Interferon treatment did not affect the association of viral RNA with the MRC structure, but cycloheximide treatment inhibited it.

Animals↗

Effect of actinomycin D and cycloheximide on replication of Sindbis virus in Aedes albopictus (mosquito) cells.

Production of Sindbis virus in the presence of transcription and translation inhibitors was examined in three Aedes albopictus cell lines. Addition of cycloheximide to heat-resistant Sindbis virus (SVHR)-infected mosquito cells arrested viral RNA synthesis completely, in contrast to the effects of this drug on virus-infected vertebrate cells. Production of mature virus by both SVHR (a variant commonly used as a wild-type virus) and SBamr (a mutant which is resistant to the effects of 18 h of pretreatment of vertebrate cells with actinomycin D) in mosquito u4.4, C6-36, and C7-10 cells was inhibited by 2 h of pretreatment with actinomycin D. Pretreatment with this drug for 2 h slightly enhances virus production in vertebrate cells. Treatment of mosquito cells with actinomycin D resulted in shutoff of SVHR RNA synthesis. The mutant SBamr was able to overcome the effects of actinomycin D on viral RNA synthesis and produced both 26S and 49S RNAs, even though no viral structural proteins or mature particles were produced in the presence of the drug. This result suggests that, in the presence of actinomycin, the nonstructural genes of SBamr are translated sufficiently to allow for RNA synthesis but that 26S RNA may not be translated to an extent that allows significant virus production. These data demonstrate that host components are involved in at least two distinct steps in the production of Sindbis virus in mosquito cells: (i) production of viral RNA and (ii) synthesis of viral structural polypeptides.

Aedes↗

Characterization of a 40S ribosomal subunit complex in polyribosomes of Saccharomyces cerevisiae treated with cycloheximide.

Under specific conditions cycloheximide treatment of Saccharomyces cerevisiae caused the accumulation of a type of polyribosome called "halfmer." Limited ribonuclease digestion of halfmers released particles from the polyribosomes identified as 40S ribosomal subunits. The data demonstrated that halfmers are polyribosomes containing an additional 40S ribosomal subunit attached to the messenger ribonucleic acid. Protein gel electrophoretic analysis of halfmers revealed numerous nonribosomal proteins. Two of these proteins comigrate with subunits of yeast initiation factor eIF2.

Cycloheximide↗

Reactivation of apolipoprotein II gene transcription by cycloheximide reveals two steps in the deactivation of estrogen receptor-mediated transcription.

In this report, we describe apolipoprotein II (apoII) gene expression in cell lines derived by stable expression of the chicken estrogen receptor in LMH chicken hepatoma cells. In cell lines expressing high levels of receptor (LMH/2A), apoII gene expression is increased by estrogen 300-fold compared with levels in the receptor-deficient parent LMH line. LMH/2A cells show apoII mRNA induction and turnover kinetics similar to those in chicken liver. Inhibition of protein synthesis with cycloheximide (CHX) or puromycin following estrogen withdrawal superinduces apoII mRNA without affecting apoII mRNA stability. Superinduction is due to an estrogen-independent reactivation of apoII gene transcription. The apoII gene can be reactivated by CHX for up to 24 h following hormone withdrawal, suggesting that the gene is in a repressed yet transcriptionally competent state. These results reveal two distinct events necessary for termination of estrogen receptor-mediated transcription. The first event, removal of hormone, is sufficient to stop transcription when translation is ongoing. The second event is revealed by the CHX-induced superinduction of apoII mRNA following hormone withdrawal. This superinduction suggests that deactivation of estrogen receptor-mediated transcription requires a labile protein. Furthermore, reactivation of apoII gene expression by CHX and estrogen is additive, suggesting that estrogen is unable to overcome repression completely. Thus, a labile protein may act to repress estrogen receptor-mediated transcription of the apoII gene.

Animals↗

NF-kappaB inducers upregulate cFLIP, a cycloheximide-sensitive inhibitor of death receptor signaling.

The caspase 8 homologue FLICE-inhibitory protein (cFLIP) is a potent negative regulator of death receptor-induced apoptosis. We found that cFLIP can be upregulated in some cell lines under critical involvement of the NF-kappaB pathway, but NF-kappaB activation was clearly not sufficient for cFLIP induction in all cell lines. Treatment of SV80 cells with the proteasome inhibitor N-benzoyloxycarbonyl (Z)-Leu-Leu-leucinal (MG-132) or geldanamycin, a drug interfering with tumor necrosis factor (TNF)-induced NF-kappaB activation, inhibited TNF-induced upregulation of cFLIP. Overexpression of a nondegradable IkappaBalpha mutant (IkappaBalpha-SR) or lack of IkappaB kinase gamma expression completely prevented phorbol myristate acetate-induced upregulation of cFLIP mRNA in Jurkat cells. These data point to an important role for NF-kappaB in the regulation of the cFLIP gene. SV80 cells normally show resistance to TNF-related apoptosis-inducing ligand (TRAIL) and TNF, as apoptosis can be induced only in the presence of low concentrations of cycloheximide (CHX). However, overexpression of IkappaBalpha-SR rendered SV80 cells sensitive to TRAIL-induced apoptosis in the absence of CHX, and cFLIP expression was able to reverse the proapoptotic effect of NF-kappaB inhibition. Western blot analysis further revealed that cFLIP, but not TRAF1, A20, and cIAP2, expression levels rapidly decrease upon CHX treatment. In conclusion, these data suggest a key role for cFLIP in the antiapoptotic response of NF-kappaB activation.

Antibodies, Monoclonal↗

Evidence that the functional beta-actin gene is single copy in most mice and is associated with 5' sequences capable of conferring serum- and cycloheximide-dependent regulation.

Hybridization to synthetic oligonucleotides representing conserved regions in the promoter and first intron of several vertebrate beta-actin genes was used to discriminate between what appears to be a single functional beta-actin gene and numerous pseudogenes in the mouse genome. Sequences derived from the 5' end of this gene were shown to confer serum-inducible expression upon a heterologous reporter gene when transfected into mouse fibroblasts. Moreover, these sequences rendered reporter gene expression superinducible by a combination of serum and cycloheximide. These experiments indicate that the 5' end of the mouse beta-actin gene contains sequence elements which mediate the stimulatory effects of serum growth factors and which are responsive to both positive and negative regulators of gene expression.

Acetyltransferases↗

A comparison of the sensitivity of immunofluorescence and Giemsa for staining Chlamydia trachomatis inclusions in cycloheximide-treated McCoy cells.

In a clinical study of 190 men with non-gonococcal urethritis, Chlamydia trachomatis inclusions were sought in cycloheximide-treated McCoy cells by an indirect immunofluorescent antibody technique. The method was consistently reliable over a period of two years, and the results were obtained within 24 hours of a patient's attendance. The results correlated with those obtained by Giemsa staining in 91.6% of patients, and the new method was at least as sensitive as the established Giemsa-staining method.

Azure Stains↗

Apolipoprotein synthesis and secretion in Hep G2 cells: effects of monensin and cycloheximide.

Hep G2 cells were used to study the relationship between apolipoprotein synthesis and secretion, as revealed by their interaction with agents modulating these processes. Cycloheximide inhibited the secretion of both apolipoproteins (apo) AI and B, but the reduction in apo AI secretion was evident at earlier times. Monensin also inhibited secretion of apo AI and apo B, but only apo AI accumulated intracellularly. Pulse-chase studies showed that, at concentrations of monensin that had no effect on total protein synthesis, apo B synthesis was specifically inhibited. Triacylglycerol synthesis was inhibited to the same extent as apo B synthesis, but this preceded the latter inhibition and unlike apo B there was an accumulation of intracellular triglyceride. These results suggest that distinctive mechanisms modulate the synthesis and secretion of apo AI and apo B, and that apo B synthesis can be specifically inhibited by mechanisms that initially block triglyceride production.

Apolipoprotein A-I↗

Induction of Na(+)-K(+)-ATPase subunit mRNAs by cycloheximide in a rat liver cell line.

Exposure of confluent Clone 9 cells to 40 microM cycloheximide (CHX), a concentration sufficient to inhibit leucine incorporation by 95% within 5 min, coordinately increased the abundances of Na(+)-K(+)-ATPase subunit mRNAs, mRNA alpha 1 and mRNA beta 1. The CHX-induced increases in mRNA alpha 1 and mRNA beta 1 abundances were, respectively, 1.8- and 1.9-fold at 40 min and 3.0- and 3.3-fold at 6 h. Augmented subunit mRNA contents were also observed after exposure to other protein synthesis inhibitors including 100 microM anisomycin and 100 microM emetine. Upon removal of CHX, the rate of leucine incorporation returned to control values within 1 h, but mRNA alpha 1 and mRNA beta 1 content decreased only slowly and were still elevated at 24 h at 1.7- and 1.8-fold the respective control values. Despite the persistence of increased levels of the subunit mRNAs and normalization of the rate of leucine incorporation, Na(+)-K(+)-ATPase activity was unchanged at 3, 6, 24, and 48 h after removal of CHX. In cells "depleted" of protein kinase C (PKC) activity after a 24-h preincubation in the presence of 160 nM 12-O-tetradecanoylphorbol-13-acetate (TPA), mRNA alpha 1 and mRNA beta 1 abundances were still inducible by CHX. It is concluded that exposure of Clone 9 cells to CHX and other inhibitors of protein synthesis results in increased abundances of Na(+)-K(+)-ATPase subunit mRNAs independently of PKC activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effects of cycloheximide on pancreatic endonuclease activity, apoptosis, and severity of acute pancreatitis.

The factors that determine the severity of acute pancreatitis are unknown, but a close inverse correlation between that severity and the extent of acinar cell apoptosis that follows the triggering signal has been previously noted [A. M. Kaiser, A. K. Saluja, A. Sengupta, M. Saluja, and M. L. Steer. Am. J. Physiol. 269 (Cell Physiol. 38): C1295-C1304, 1995]. In the present studies, we have evaluated internucleosomal DNA fragmentation and apoptosis within the pancreas and the effects of inhibiting protein synthesis by cycloheximide (CHX) on these phenomena as well as on the severity of pancreatitis. We report the constitutive presence of a Ca(2+)- and Mg(2+)-dependent endonuclease activity within pancreatic nuclei that is dependent on continued protein synthesis. Furthermore, we have found that CHX administration reduces the extent of apoptosis but significantly worsens the severity of pancreatitis that follows ligation of the rat common bile-pancreatic duct. These observations are consistent with the hypothesis that apoptosis is a teleologically beneficial response to acinar cell injury during acute pancreatitis.

Animals↗

Cholera-induced mucin secretion from rat intestine: lack of effect of cAMP, cycloheximide, VIP, and colchicine.

Purified cholera enterotoxin (20-50 micrograms) and dialyzed cholera filtrate (50-125 mg) increased net glycoprotein synthetic and secretory rates in rat intestinal epithelium. Specific goblet cell mucin secretion was increased 5- to 10-fold. However, other agents that increase intestinal cAMP and accelerate glycoprotein synthesis did not enhance mucin secretion. This was true for dibutyryl cAMP (10(-3) and 10(-2) M) with or without theophylline (10(-3) M) and isoproterenol (10(-4) M) with or without dibutyryl cAMP (10(-3) M). Hyperosmotic mannitol (450 mosmol/l), which increases fluid secretion but does not affect cAMP, and vasoactive intestinal peptide (2 X 10(-7) M), which increases both fluid secretion and cAMP, both failed to increase mucin secretion, implying that fluid "washout" of mucin adherent to the mucosal surface is not responsible for cholera-induced mucin secretion. Cycloheximide, an inhibitor of cholera diarrhea in vivo (20 mg/kg) or in vitro (1 mM), effectively abolished [3H]leucine incorporation into protein but did not affect cholera-induced mucin secretion. Colchicine (10-50 mg/kg) given to block microtubule assembly was similarly without effect on mucin secretion. These findings suggest that there is a dissociation of electrolyte/fluid and mucin secretory processes and cast doubt on the widely accepted notion that all cholera effects are mediated via the well-known adenylate cyclase-cAMP mechanism.

Animals↗