The transcript-level-independent activation of ornithine decarboxylase in suspension-cultured BY2 cells entering the cell cycle.
The regulation of ornithine decarboxylase (ODC) expression was studied in suspension-cultured tobacco (Nicotiana tabacum L.) BY2 cells. ODC activity increased rapidly 3 h after cells re-entered the cell cycle from the stationary phase, corresponding to the G1 phase, and continued to increase in the subsequent S phase, while the ODC transcript level increased only transiently. ODC activity was suppressed by sucrose-deficiency, while the ODC transcript level was not affected. U0126, a specific inhibitor of mammalian MAPK kinases (MEKs), significantly reduced ODC enzyme activity, but not the ODC transcript level. These results suggest that ODC activity is regulated independently of its transcript level in BY2 cells, and that sucrose and a U0126-sensitive protein kinase are required for the transcript-level-independent activation of ODC.
Kwak
Su-Hwan
SH
Department of Biology, Yonsei University, Shinchon-dong 134, Seodaemun-gu, Seoul 120-749, Korea.
Lee
Sun Hi
SH
D002070:Butadienes / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D002478:Cells, Cultured; D016193:G1 Phase / Q000235:genetics / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D009570:Nitriles / Q000494:pharmacology; D009955:Ornithine Decarboxylase / Q000235:genetics* / Q000378:metabolism; D016196:S Phase / Q000235:genetics / Q000502:physiology; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects
D002070:Butadienes; D009570:Nitriles; C113580:U 0126; D020929:Mitogen-Activated Protein Kinase Kinases; D009955:Ornithine Decarboxylase