Cycloheximide synthesis

Those herbicides that block mitotic entry decrease or prevent the formation of mitotic figures in meristems. Amino acid, protein, RNA, DNA, and ATP synthesis and/or utilization can all attest cell growth (163,166). Although not registered as herbicides, cycloheximide [66-81-9] inhibits mitotic entry by inhibiting protein synthesis (167) hydroxyurea/727-(97-/7 inhibits DNA synthesis (168) and actinomycin D [50-76-0] nh2oix.s RNA synthesis (167). 

Accumulation of lipids in the liver (steatosis) is one possible mechanism for liver toxicity. Several compounds causing necrosis of hepatocytes also cause steatosis. There are, however, some doubts that steatosis would be the primary cause of liver injury. Several compounds cause steatosis (e.g., puro-mycin, cycloheximide) without causing liver injury. Most of the accumulated lipids are triglycerides. In steatosis, the balance between the synthesis and excretion of these lipids has been disturbed (see Table 5.13). 

The acylation of enamines has been applied to the use of long-chain acid chlorides (388) and particularly to the elongation of fatty acids (389-391) and substituted aliphatic acids (392). The method has been used in the synthesis of the antineoplastic cycloheximide and related compounds (393-395) and in the acylation of steroids (396). Using an optically active chlorocarbonate, an asymmetric synthesis of lupinine could be achieved (397). 

Other antibiotics inhibit protein synthesis on all ribosomes (puromycin) or only on those of eukaryotic cells (cycloheximide). Puromycin (Figure 38—11) is a structural analog of tyrosinyl-tRNA. Puromycin is incorporated via the A site on the ribosome into the carboxyl terminal position of a peptide but causes the premature release of the polypeptide. Puromycin, as a tyrosinyl-tRNA analog, effectively inhibits protein synthesis in both prokaryotes and eukaryotes. Cycloheximide inhibits peptidyltransferase in the 60S ribosomal subunit in eukaryotes, presumably by binding to an rRNA component. 

Many of these compounds—puromycin and cycloheximide in particular—are not cfinically useful but have been important in elucidating the role of protein synthesis in the regulation of metabolic processes, particularly enzyme induction by hormones. 

Feedback inhibition of amino acid transporters by amino acids synthesized by the cells might be responsible for the well known fact that blocking protein synthesis by cycloheximide in Saccharomyces cerevisiae inhibits the uptake of most amino acids [56]. Indeed, under these conditions, endogenous amino acids continue to accumulate. This situation, which precludes studying amino acid transport in yeast in the presence of inhibitors of protein synthesis, is very different from that observed in bacteria, where amino acid uptake is commonly measured in the presence of chloramphenicol in order to isolate the uptake process from further metabolism of accumulated substances. In yeast, when nitrogen starvation rather than cycloheximide is used to block protein synthesis, this leads to very high uptake activity. This fact supports the feedback inhibition interpretation of the observed cycloheximide effect. 

Rehner This suggestion is not sufficient to explain your results with cycloheximide. If cycloheximide is added, the inhibitor should already have been made. In this case the timing can only work if a protein degradation system is switched on on time in the absence of protein synthesis. 

The suppression and recovery of protein synthesis from DTT treatment (without cycloheximide treatment) can be monitored via metabolic pulse radiolabeling of cell cultures using [35S]-methionine and subsequent determination of radiolabeled protein content either by SDS-PAGE/ phosphor-imager analysis or liquid scintillation of tricholoroacetic acid insoluble material (Stephens et al., 2005). 

Obrig, T. G., Culp, W. J., McKeehan, W. L., and Hardesty, B. (1971). The mechanism by which cycloheximide and related glutarimide antibiotics inhibit peptide synthesis on reticulocyte ribosomes. J. Biol. Chem. 246, 174-181. 

IL-6 expression can be activated in neutrophils upon exposure to GM-CSF and TNF, whilst IL-3, G-CSF, y-interferon and lymphotoxin do not induce expression of this cytokine. Expression of IL-6 has been identified by analysis of mRNA levels and by protein analysis. Following GM-CSF exposure, expression is detectable by 2 h, maximal by 6 h and then returns to base-line levels. LPS, PMA (but not fMet-Leu-Phe) and cycloheximide also induce IL-6 transcripts. The finding that this protein-synthesis inhibitor increases mRNA levels suggests either that transcription is regulated by a short-lived repressor, or else that decay of its mRNA may be regulated by a short-lived RNase. 

Messenger RNA molecules for both subunits of the cytochrome and the two cytosolic components are detectable in unstimulated bloodstream cells. Experiments involving incubation of neutrophil suspensions with the protein synthesis inhibitor cycloheximide indicate that constitutive expression of one or more components of the oxidase is required for the neutrophil to maintain its ability to generate reactive oxidants. For example, when neutrophils are incubated in vitro with cycloheximide, their ability to generate reactive oxidants declines more rapidly than in control cells, as they age in culture (Fig. 7.12). This decline in oxidase activity when protein biosynthesis is blocked is not due to cell death, because cells treated with cycloheximide for this time still exclude trypan blue. Furthermore, when protein biosynthesis is stimulated in neutrophils by the addition of GM-CSF for 24 h in vitro, the ability to generate reactive oxidants is enhanced considerably above the levels observed in untreated cells. 

The use of antibiotics for the control of plant virus diseases( ) is of interest. Several antibiotics have been tested for inhibition of replication of viral nucleic acid and/or protein synthesis within the host cell. Chloramphenicol, cycloheximide, actinomycin D and others are the most used antibiotics and the disease caused by tobacco mosaic... 

Alice et al studied the turnover kinetics of Listeria OTonocytogenex-secreted p60 protein (a murein hydrolase) by host cell cytosolic proteasomes. J774 cells, seeded in flasks and incubated overnight in culture medium, were infected with log-phase cultures of E. monocytogenes for 30 min, washed, and incubated in culture medium for 3 h, with gentamicin (50 tg/ml) added after the first 30 min to inhibit extracellular bacterial growth. Cells then were washed and placed in methionine-free medium with spectinomycin, gentamicin, the eukaryotic protein synthesis inhibitors [cycloheximide (50 tg/mL) and anisomycin (30 tg/ml),] and 25 dVI calpain inhibitor I. After 30 min, [ S]methionine was added, and the cells were pulse-labeled for periods of 20 to 60 min. Cells... 

Kinase inhibitors such as H7, which inhibits serine threonine kinases, resulted in sustained JAK2/STAT activation, suggesting that besides protein dephosphorylation, protein phosphorylation is also required. Furthermore, both inhibition of protein synthesis with cycloheximide and inhibition of... 

Obviously, there is some kind of cross-talk between PKC and cAMP in the modulation of intercellular coupling, since cAMP can inhibit the uncoupling effect of phorbol esters if cells are exposed to both agents from the start of the experiment [Kanno et al., 1984], but this protective effect can be abolished by the protein synthesis inhibitor cycloheximide [Enomoto et al., 1984] in Balb/ cells. 

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