Protein synthesis inhibitors, like growth factors, may render resting 3T3 cells competent for DNA synthesis: a radioautographic and cell fusion study

Abstract

Serum-deprived (0.1-0.2%) resting NIH 3T3 mouse fibroblasts pre-incubated with cycloheximide (7.5 micrograms/ml), or puromycin (10 micrograms/ml), were fused with stimulated cells taken 10 h after changing the medium to one containing 10% serum, and DNA synthesis was investigated in the nuclei of monokaryons, homodikaryons and heterodikaryons using radioautography with the double-labelling technique. Pre-incubation of resting cells with inhibitors of protein synthesis for 1-4 h abolished their ability to suppress DNA synthesis in stimulated nuclei in heterokaryons. Three hours after the removal of cycloheximide from the medium, the resting cells acquired once again the inhibitory capacity for entry of stimulated nuclei into the S period. This inhibitory influence disappeared also in the case of post-fusion cycloheximide application as well as following an 8-12 h pre-treatment of resting cells with actinomycin D (1 microgram/ml) prior to fusion. Pre-incubation of resting cells for 12 h with PDGF (1 u/ml-1) followed by an 8-48 h incubation in serum-free medium stimulated the onset of DNA synthesis. A brief exposure (45 min) of resting cells to cycloheximide (7.5 micrograms/ml), or puromycin (7.5 micrograms/ml), exerted a similar effect, inducing by itself the entry of cells into the S period. The results support the assumption that acquirement, by resting cells, of competence for DNA replication includes as a necessary step the down-regulation of intracellular growth inhibitors whose formation depends on protein synthesis.

Protective Role of Tissue Transglutaminase in the Cell Death Induced by TNF-α in SH-SY5Y Neuroblastoma Cells

“…4). Cycloheximide inhibits protein synthesis and induces cell death in many cell types (Setkov et al, 1992;Suzuki et al, 1992;Tang et al, 1999). The tTGase protein level was investigated by Western blotting after incubation with TNF-α and cycloheximide.…”

Neural precursor cells possess multiple p53-dependent apoptotic pathways

“…31 Cycloheximide (CHX), an inhibitor of new protein translation, disrupts the 80S ribosome interactions with cytosolic mRNA. 32 It has been shown that the induction of proapoptotic genes in neuronal cells can be attenuated using 0.1-1.0 mg/ml of actinomycin D or CHX. 33 Over a 24 h period, these agents alone cause NPC death in a concentration-dependent manner (data not shown), as is expected since a baseline level of transcription and translation is required for NPC survival.…”

High Light Acclimation in the Secondary Plastids Containing Diatom Phaeodactylum tricornutum is Triggered by the Redox State of the Plastoquinone Pool

“…Cycloheximide (CHX) blocks the translation of nucleus-encoded genes on cytosolic 80S ribosomes and therefore does not influence gene translation in the organelles (Obrig et al, 1971;Setkov et al, 1992). As a matter of fact, while HL treatment induced the synthesis of nucleus-encoded LHCX2 and LHCX3 proteins (Fig.…”