Transient increase in the c-fos mRNA level after change of culture condition from serum absence to serum presence and after cycloheximide addition in rat 3Y1 fibroblasts.
When 3Y1 cells resting at a saturation density were mitotically stimulated with serum, the c-fos mRNA level markedly increased in a short period of time and then decreased rapidly to an undetectable level. Subsequent serum deprivation followed by serum re-addition or subsequent cycloheximide addition caused a transient re-increase in the c-fos mRNA level. These results can be explained by assuming that the continuous expression of the c-fos gene at a minimum level is necessary for the eventual initiation of S phase, and that the over-expression of the c-fos gene occurs when the control of the gene expression is transiently disturbed by the change of the culture condition.
Okuda
A
A
Department of Virology, Kyushu University, Fukuoka, Japan.
Matsuzaki
A
A
Kimura
G
G
D000818:Animals; D002999:Clone Cells / Q000187:drug effects / Q000378:metabolism; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D007399:Interphase / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats
D003470:Culture Media; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D003513:Cycloheximide