Enhanced transcription of c-myc in bursal lymphoma cells requires continuous protein synthesis.
In several bursal lymphoma cell lines in which c-myc transcription is regulated by avian leukosis virus (ALV) long terminal repeat (LTR) sequences, protein synthesis inhibition decreases the transcriptional activity of c-myc as well as other LTR driven viral genes. This decrease in transcription is associated with a change in the chromatin structure of c-myc, as measured by deoxyribonuclease I (DNase I) hypersensitivity, and a shift of transcription from the LTR to the normal c-myc promoter. In contrast, cycloheximide had little or no effect on the transcription of LTR driven genes in infected chicken embryo fibroblasts treated with the drug. These results suggest that a labile, cell type-specific protein may interact with the retroviral LTR and regulate transcription of genes under LTR control. Further, the results demonstrate that the increase in intracellular concentration of c-myc RNA induced by cycloheximide treatment of normal cells is the result of stabilization of this message.
D000818:Animals; D001353:Avian Leukosis / Q000235:genetics; D001354:Avian Leukosis Virus; D002060:Bursa of Fabricius / Q000166:cytology; D002460:Cell Line; D002642:Chick Embryo; D002645:Chickens; D002843:Chromatin / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004640:Emetine / Q000494:pharmacology; D008223:Lymphoma / Q000235:genetics*; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D009857:Oncogenes; D012334:RNA, Neoplasm / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects
D002843:Chromatin; D009363:Neoplasm Proteins; D012334:RNA, Neoplasm; D003609:Dactinomycin; D003513:Cycloheximide; D004640:Emetine