Cell cycle dependent regulation of cdc2 mRNA in mouse fibroblasts: requirement of protein synthesis and of continued mitogenic stimulation.
In the chemically transformed mouse fibroblasts (BP-A31) placed in a serum-free medium, the cdc2 mRNA content decreases in parallel with the cessation of [3H]thymidine incorporation. Extinction of the cdc2 gene expression is also observed in BP-A31 cells overexpressing the human c-myc oncogene. At quiescence, the cdc2 gene expression can be reinduced with serum or with other mitogens such as insulin or 12-O-tetradecanoyl phorbol 13-acetate (TPA). The kinetics of induction is characterized by a lag period which differs according to the mitogen used and reflects the length of the G1 phase (4-6 h with insulin or serum, 9-12 h with TPA). The cdc2 mRNA accumulation is prevented when protein synthesis is blocked with cycloheximide, also if the drug is added at a time when the synthesis of cdc2 mRNA is already under way. Similarly, removal of the mitogen leads to a cessation of the cdc2 mRNA accumulation. These results suggest that the increased expression of the cdc2 gene is mediated by (a) short-lived, growth factor-regulated protein(s).
Buquet-Fagot
C
C
INSERM U.55, Paris, France.
Fagot
D
D
Mester
J
J
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D001769:Blood; D016203:CDC2 Protein Kinase / Q000235:genetics*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D003907:Dexamethasone / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000378:metabolism*
D008934:Mitogens; D012333:RNA, Messenger; D003907:Dexamethasone; D016203:CDC2 Protein Kinase; D015056:1-Methyl-3-isobutylxanthine