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PubMed1991

[Increase in the quantity of highly repetitive sequences in extrachromosomal circular DNAs under inhibition of translation by cycloheximide].

Small polydispersed circular DNA(spcDNA) was isolated from cultivated HeLa cells. Cells were treated by cycloheximide in concentrations of 1 and 50 micrograms/ml. Gradient fractions were dot blotted to nitrocellulose filters and were hybridized with different repetitive DNAs. The pool of repetitive DNA sequences in fraction of spcDNA increased for cycloheximide treated cells. The content of Alu sequences increased by 1.5-2.5 times, "classical" satellite DNA--by 5-7 times, alpha-satellite--by 3-5 times.

Cycloheximide↗
PubMed1977

[Potentiating effect of cycloheximide on viral interference].

The degradation of the antiviral state can be delayed in vitro by antimetabolites, when added between 5-7 hours after interferon. We explore in this chronological order whether antiviral resistance induced by Newcastle disease virus (N.D.V.) in vivo could be modified by an antimetabolite. Cycloheximide was selected for this study because of its reversible biological effect and lack of toxicity in our experimental conditions. The model system employed was Syrian Hamsters, using N.D.V. as an interferon inducer and encephalomyocarditis virus (E.M.C.) as a challenge virus. A constant and significant increase in survival of animals treated with N.D.V.+cycloheximide is probably related to a delay in the degradation of the antiviral state and not to interferon superinduction.

Animals↗
PubMed1990

Induction of HSP27 phosphorylation and thermoresistance in Chinese hamster cells by arsenite, cycloheximide, A23187, and EGTA.

Incorporation of [3H]leucine, immunochemical analyses with a specific hamster HSP27 rabbit immunoserum, and [32P]orthophosphate labeling were used to monitor synthesis, accumulation, and phosphorylation of HSP27 in Chinese hamster cells after induction of thermoresistance by arsenite, cycloheximide, A23187, and EGTA. In contrast to arsenite-induced thermotolerance, which develops in parallel to synthesis and accumulation of HSP27, enhanced thermoresistance observed immediately after incubating cells in the presence of cycloheximide, A23187, or EGTA is independent of HSP27 or other HSP accumulation. All these treatments, however, result in a rapid phosphorylation of preexisting HSP27. In view of previous results which indicated that HSP27 is involved in cell protection from thermal killing (J. Landry, P. Chrétien, H. Lambert, E. Hickey, and L. A. Weber, J. Cell Biol. 109, 7-15, 1989), it is proposed that activation of HSP27 through phosphorylation may be a key determinant in the regulation of cell thermosensitivity.

Animals↗
PubMed1978

Effect of thyroid hormone, actinomycin D, cycloheximide and puromycin on TRH-induced secretion of TSH, as studied by pituitary concentration of cyclic AMP and intrathyroidal colloid droplet formation.

In an attempt to study the functional relation between pituitary cyclic AMP and TSH secretion in response to thyrotropin releasing hormone (TRH) or thyroid hormone administration, pituitary concentration of cyclic AMP was measured by protein binding assay after in vivo and in vitro administration of test materials (TRH, thyroxine, triiodothyronine, actinomycin D, puromycin and cycloheximide singly or in combination). Small dose of TRH apparently augmented TSH secretion as evidenced by a marked increase of intrathyroidal colloid droplet, but failed to elevate the pituitary concentration of cyclic AMP. Triiodothyronine (T3) and thyroxine (T4) blocked an increase of TSH secretion produced by TRH, but they elevated pituitary concentration of cyclic AMP in vivo and in vitro. Actinomycin D (Act D), puromycin and cycloheximide elevated pituitary cyclic AMP concentration without stimulating TSH secretion. From the data accumulated, it appears that the measurement of total anterior pituitary concentration of cyclic AMP is not useful to evaluate the activity of TSH cells in response to thyroid hormone, TRH and TRH plus thyroid hormone.

Animals↗
PubMed1990

MHC class II-restricted presentation of native protein antigen by B cells is inhibitable by cycloheximide and brefeldin A.

The presentation of protein Ag with MHC class II proteins involves the uptake of the protein Ag by endocytosis followed by processing, probably proteolysis, in an intracellular acidic compartment. However, there remains considerable controversy as to the precise route taken by the antigen and the MHC class II protein during this process. The unusual stability of Ag-MHC class II protein complexes has led to speculation that antigen can only associate with newly synthesized MHC class II molecules. An alternate possibility is that the MHC class II binding site can be regenerated within the cell during internalization and recycling of MHC class II proteins. To address these possibilities, three different murine B lymphoma lines were tested for their ability to process and present native protein Ag in the presence of the protein synthesis inhibitor cycloheximide or the protein synthesis inhibitor cycloheximide or the protein export inhibitor, Brefeldin A. Both agents blocked the presentation of native OVA or native hen egg lysozyme to Ag-specific T cell hybridomas. No effect was seen on peptide presentation or on presentation to allo- or autoreactive T cells. Inasmuch as Brefeldin A has been previously shown to block protein export without affecting protein internalization or protein degradation in the endocytic pathway, the simplest interpretation of these data is that antigenic fragments generated in the APC after uptake by the endocytic pathway, preferentially associate with newly synthesized rather than mature MHC class II proteins.

Animals↗
PubMed1989

[Effect of cycloheximide on lipid metabolism in cells, nuclei and subcellular fractions in the rat liver].

Well coordinated stages of inhibition, restoration and stimulation of protein, DNA and RNA synthesis were observed after administration of cycloheximide (3 mg/kg). The changes in lipid synthesis and composition in the nuclei and intranuclear structures were studied at different stages of cycloheximide action. The accumulation and stimulation of lipid synthesis in the nuclei during the inhibition and restoration of protein and DNA syntheses were followed by electron microscopy and labeled precursors methods. Dramatic changes were observed in the phospholipid composition of chromatin and nuclear matrix. The accumulation of minor phospholipid fractions in intranuclear structures was observed during DNA synthesis. The sphingomyelin concentration was predominant and commensurable with those of phosphatidylcholine and phosphatidylethanolamine.

Animals↗
PubMed1989

The kinetics of steroidogenesis activator polypeptide in the rat adrenal cortex. Effects of adrenocorticotropin, cyclic adenosine 3':5'-monophosphate, cycloheximide, and circadian rhythm.

The behavior of steroidogenesis activator polypeptide (SAP), a recently described modulator of cholesterol side-chain cleavage activity (Pedersen, R. C., and Brownie, A. C. (1987) Science 236, 188-190), was investigated in rat adrenocortical cells using a specific radioimmunoassay. In response to a maximal dose of adrenocorticotropic hormone (ACTH) (1 nM) or of 8-Br-cAMP (1 mM), an increase in intracellular SAP begins rapidly (less than 1 min) and reaches half-maximal and maximal levels (16-fold greater than basal) at 3 and 15 min, respectively. A plateau at this maximal concentration of SAP is then maintained. The levels of intracellular SAP content and of corticosterone output exhibit a similar dose-dependent response to ACTH (EC50 = 25 and 30 pM, respectively). Treatment of ACTH-stimulated cells with cycloheximide reverses the rise in SAP (t1/2 congruent to 5-7 min). In vivo the SAP content of adrenals from quiescent rats is concordant with the circadian rhythm of the pituitary-adrenal axis; at the apex (1800 h), adrenal SAP is 13-fold higher than at the nadir (0800 h), paralleling 2- and 7-fold variations in cholesterol side-chain cleavage activity and serum corticosterone levels, respectively. At both time points, SAP levels rise in response to stress. Of the rat tissues examined, only the major steroid-forming organs (adrenal cortex and gonads) had significant levels of immunoreactive, cAMP-responsive SAP, while cAMP-unresponsive immunoreactivity was also detectable in the thymus, spleen, and brain. Considered together with the biological activity previously demonstrated for SAP in vitro, these data are consistent with its role as a cAMP-dependent, cycloheximide-sensitive modulator of steroid biosynthesis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1989

One trial conditioning with apomorphine is blocked by cycloheximide.

Rats with unilateral 6-hydroxydopamine lesions of substantia nigra were treated with 0.05 mg/kg apomorphine and observation of their circling behavior was made. Twenty minutes after the apomorphine treatment they were injected with saline or 2 mg/kg cycloheximide. Two weeks after drug treatment, control animals exhibited rapid contralateral rotation in response to being placed in the rotation environment. This conditioned rotation was not observed in cycloheximide-treated animals. After the first test trial animals received a second apomorphine administration, this time followed by saline injection in both groups. Subsequent to the second apomorphine treatment both groups showed conditioned rotation.

Animals↗
PubMed1989

Purification of a hepatic S6 kinase from cycloheximide-treated Rats.

Cycloheximide injection of rats results in the activation of a protein kinase that phosphorylates 40 S ribosomal protein S6. This Ca2+/cyclic nucleotide-independent kinase exhibits chromatographic properties that are indistinguishable from the S6 kinase in H4 hepatoma cells whose activity is stimulated by insulin and growth factors and the S6 kinase that is activated during liver regeneration. The enzyme has been purified 50,000-fold to near homogeneity: a critical step in purification employs a peptide affinity column using a synthetic peptide corresponding to the carboxyl-terminal 32-amino acid residues of mouse liver S6, which encompasses all S6 phosphorylation sites. The purified enzyme is a 70,000-dalton polypeptide that is reactive with azido-ATP. In addition to 40 S ribosomal S6 and the synthetic peptide, the S6 kinase catalyzes rapid phosphorylation of a number of other protein substrates including histone H2b, glycogen synthase, and ATP citrate lyase; this last protein is phosphorylated by S6 kinase in vitro on the same serine residue that is phosphorylated in response to insulin and epidermal growth factor in intact hepatocytes. Moreover, the S6 kinase catalyzes the phosphorylation of a number of hepatic nonhistone nuclear proteins. This S6 kinase probably underlies the increased hepatic S6 phosphorylation observed after cycloheximide treatment, which in turn corresponds to the mitogen-activated S6 kinase.

Animals↗
PubMed1988

[Modification by cycloheximide of the effects of insulin on the transport of calcium by sarcolemma of the myocardium].

The inhibitory effect of insulin on Ca2+-current was supposed to be due to activation of phosphoproteinphosphotases stimulated by a specific intracellular insulin messenger. The results obtained support the above suggestion. Pretreatment of myocardial preparation with cycloheximide in low concentrations completely blocks the inhibitory insulin effect on Ca2+-current due, probably, to a decrease in peptide formation. Moreover, prolonged effect of the hormone involves a considerable increase of the current as compared to its initial value. Possible mechanisms of modifying effect of cycloheximide on the function of insulin-dependent regulatory system in the myocardium, are discussed.

Animals↗
PubMed1978

The use of cycloheximide-treated cells for isolating trachoma agents under field conditions.

Standard procedures for the isolation of Chlamydia trachomatis require pretreatment of the tissue culture cells. We evaluated the use of cycloheximide, an antimetabolite that can be added to the cells with the inoculum. Cycloheximide-treated cells provided a sensitive system for isolating trachoma agents. This system was applicable to field studies as requirements for equipment were minimal and the cells were 2 weeks old when inoculated.

Chlamydia trachomatis↗
PubMed1988

Human adrenodoxin: cloning of three cDNAs and cycloheximide enhancement in JEG-3 cells.

Adrenodoxin is an iron-sulfur protein serving as an electron transport intermediate for two mitochondrial steroidogenic cytochromes P450. We have cloned and sequenced three human adrenal adrenodoxin cDNAs. The longest 5'-untranslated region was 131 bases long, and the coding sequences, identical in all three clones, predict a preprotein of 180 amino acids. The 3'-untranslated regions were 235, 596, and 776 bases long due to the presence of alternate polyadenylation sites. RNA transfer blots showed multiple size species of adrenodoxin mRNA consistent with finding multiple polyadenylation sites. Similar sized cross-hybridizing RNA species are found abundantly in the adrenal and testis and to a lesser degree in RNA from human fetal brain, spleen, placenta, kidney, liver, and intestine, as well as in cultured fibroblasts, suggesting the same or a very similar iron-sulfur protein is found in mitochondria of nonsteroidogenic tissues. JEG-3 cells, a transformed progesterone-producing line of trophoblastic origin, accumulate mRNAs for cytochrome P450scc (the mitochondrial cholesterol side-chain cleavage enzyme), adrenodoxin, and the fos oncogene when stimulated with 8-bromo-cyclic AMP. Addition of actinomycin D to such cultures blocked cAMP-induced accumulation of mRNAs for cytochrome P450scc and adrenodoxin. Addition of cycloheximide or puromycin to such cultures substantially reduced basal levels and markedly attenuated the cAMP-induced accumulation of cytochrome P450scc mRNA, but augmented the accumulation of adrenodoxin and fos mRNAs in additive and multiplicative fashions, respectively. These data indicate that the cAMP-induced synthesis of the steroidogenic machinery is not wholly dependent on cycloheximide-sensitive protein mediators.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1988

Identification of the 40 S ribosomal protein S6 phosphorylation sites induced by cycloheximide.

Injection of cycloheximide into rats induced the incorporation of up to 5 mol of phosphate/mol of liver 40 S ribosomal protein S6. Treatment of the protein with cyanogen bromide generated three phosphopeptides of Mr approximately 31,000, approximately 27,000, and approximately 4,000. Increasing the concentration of cyanogen bromide or redigestion of the larger peptides with additional cyanogen bromide converted almost all the phosphate-containing peptides into the Mr approximately 4,000 peptide. This peptide was isolated by reverse phase high pressure liquid chromatography, and the phosphoserines were identified by amino acid sequence analysis after being converted to S-ethyl-cysteine. The results show that the phosphate is incorporated into 5 of 7 serines clustered in a small 13-amino acid segment of the protein. By aligning the sequence of the Mr approximately 4,000 peptide with the recently published mouse cDNA sequence of S6, it is shown that this peptide resides at the carboxyl terminus of the protein. The relevance of the cycloheximide-induced sites of S6 phosphorylation to those stimulated by a variety of mitogens and oncogenes is discussed.

Animals↗
PubMed1979

[Effect of cycloheximide, 2,4-dinitrophenol and papaverine on ribosomal RNA synthesis in Ehrlich ascitic carcinoma cells].

The influence of 2,4-dinitrophenol (DNP), papaverine and cycloheximide on RNA synthesis in Ehrlich ascites tumour cells has been investigated. All above mentioned agents inhibit selectively synthesis of high-molecular rRNA precursor, when the cell population density is 3.10(7)--5.10(7) per 1 ml of suspension. When the density of cells decreases as far as 1.10(6) cells per 1 ml. the rRNA synthesis loses the sensitivity to all these agents. The effects of both cycloheximide on the protein synthesis and DNP on ATP level do not depend on the cell population density in suspension. It is suggested that either with a decrease of cell population density the protein synthesis and ATP level cease playing the role of a rate-limiting factor in the rRNA synthesis, or the influence of agents studied is realized by means of their interaction with other cell system.

Adenosine Triphosphate↗
PubMed1979

Stability in Newcastle disease virus-infected cells of HN protein which lost its functional activity under conditions of protein synthesis inhibition by cycloheximide.

Chick embryo cell cultures were infected with Newcastle disease virus (strains Italia, Beaudette and B1), labelled with 14C-amino acids from 5 to 6 hr post infection (p.i.), incubated in chase conditions from 6 to 10 hr p.i. in the presence or absence of cycloheximide (100 microgram/ml) and analyzed by slab polyacrylamide gel electrophoresis and autoradiography. In chase experiments the HN protein was stable in all three strains. The haemagglutinating activity of cell homogenates was greatly reduced after the addition of cycloheximide in tests with Beaudette and B1 strains; treatment of the homogenates with neuraminidase from Vibrio cholerae did not influence this effect.

Animals↗
PubMed1979

[Biogenesis of chromatin in animal cells. Stimulation of nuclear protein and DNA synthesis in hepatocytes after brief inhibition of translation by cycloheximide].

A drastic and brief inhibition of protein synthesis (up to 95% for 3--6 hrs) by cycloheximide in the liver of rats starved for 24 hrs results in a recovery and subsequent marked stimulation of non-histone proteins, histone chromosomal proteins and DNA. The stimulation of non-histone protein synthesis was observed after 1 hr (inhibition) 12--24 hrs (recovery and stimulation of protein synthesis) and 48--60 hrs (stimulation of DNA synthesis) following the administration of cycloheximide. Two periods of histone biosynthesis were observed. The first one (24--36 hrs) was not coupled and the second one (48--60 hrs) was coupled with DNA replication. During the recovery and stimulation of protein synthesis acetylation of the histone and non-histone proteins proceeds at an increased rate. Possible applicability of the model in question for investigations of chromatin biogenesis is discussed.

Animals↗
PubMed1979

Inhibition of liver protein degradation in vivo by intensive treatment with cycloheximide.

The AA in experiments performed on male rats treated with 0,5 mCi/kg of cycloheximide have observed an inhibition of liver protein degradation and have suggested two mechanism: 1) cycloheximide prevents the acute proteolytic response induced in fibroblast culture by exposure to serum-deficient media and in rat livers after perfusion probably by inhibiting the lysosomal - autophagic system, without modifications in total activity of lysosome proteinases. 2) It may be that protein degradation rate and level of lysosomal proteinases reinterrelated; the latter probably being a factor controlling the overall cell protein turnover rate.

Animals↗
PubMed1977

[Polysomal apparatus as a reflection of function interactions between translation and transcription processes during protein synthesis inhibited by cycloheximide].

Distribution of optical density and radioactivity in sucrose density gradient was studied for 14C-RNA and 3H-protein polysomal components isolated from normal rat liver 1, 3, 6 12 and 24 hrs after cycloheximide (CHI) treatment (sublethal dose--0,3 mg/100 g body weight). Soon after the antibiotic injection (1--3 hrs), when protein biosynthesis was strongly inhibited (more than 90%), the total quantity of "heavy" polyribosomes and 14C-mRNA associated with this fraction significantly increased. At the same time the amount of free ribosomes showed a decrease. On the contrary, after 6 hrs the amount of polysomes sharply decreased and that of ribosomes and their subunits was increased. In the middle period and at the end of experiment (12--24 hrs) when protein biosynthesis was continuously restored, the polysomes sedimentation pattern was restored as well. Specific radioactivity of 14-C-rRNA's and 3H-proteins in this fraction was also increased. The restoration of optimal protein biosynthesis level after its inhibition by a single cycloheximide injection (sublethal doses) is thought to be a complex process of consecutive interactions between translation and transcription cell systems.

Animals↗