Gene activation in WI-38 fibroblasts stimulated to proliferate: requirement for protein synthesis.
Confluent monolayers of WI-38 human diploid fibroblasts can be stimulated to divide by fresh medium containing 30% fetal-calf serum. Up to 80% of the cells are stimulated to divide, with a peak of DNA synthesis between 15 and 21 hr. 1 hr after the change of medium there is a 70% rise in chromatin template activity. Cycloheximide inhibited the increase in chromatin template activity. A requirement for RNA synthesis was investigated by incubating stimulated and unstimulated cells with 10 mug/ml of actinomycin D. In spite of a 95% inhibition of RNA synthesis in whole cells, purified chromatin from stimulated cells showed the usual increase in template activity. These experiments implicate a requirement for protein synthesis in template activation, and imply that the synthesis of this (or these) protein(s) is independent of RNA synthesis and regulated by a purely translational mechanism.
D001345:Autoradiography; D002455:Cell Division; D002478:Cells, Cultured / Q000378:metabolism; D002843:Chromatin / Q000032:analysis / Q000096:biosynthesis; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D003609:Dactinomycin / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007930:Leucine / Q000378:metabolism; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D013268:Stimulation, Chemical; D013698:Templates, Genetic; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D002843:Chromatin; D003470:Culture Media; D014316:Tritium; D003609:Dactinomycin; D012313:RNA; D004247:DNA; D003513:Cycloheximide; D007930:Leucine; D013936:Thymidine