Shift from posttranscriptional to predominant transcriptional control of the expression of the GM-CSF gene during activation of human Jurkat cells.
The expression of the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene is differentially regulated in various cell types. We investigated the mechanisms controlling its expression in 12-O-tetradecanoylphorbol-13-acetate plus phytohemagglutinin-stimulated Jurkat cells, a human T-cell line. In unstimulated cells, GM-CSF mRNA was undetectable by Northern blot. Upon activation, it was detected from 3 h onward, with a progressive increase in the levels of the transcript up to 24 h of stimulation. Whereas cycloheximide treatment at the time of stimulation blocked mRNA induction, its addition at later times resulted in a marked increase in transcript levels. Run-on analysis showed that transcription of the GM-CSF gene was low to undetectable in unstimulated cells; stimulation led to transcriptional activation, which was weak at 6 h but had increased 16-fold at 24 h. In addition, the mRNA half-life decreased during activation, from 2.5 h at 6 h down to 45 min at 24 h. Cycloheximide treatment increased GM-CSF mRNA half-life (3- and 4-fold, respectively). Our results show: (a) both transcriptional and posttranscriptional signals regulate GM-CSF mRNA levels in activated Jurkat cells, (b) de novo protein synthesis is required for mRNA induction, whereas destabilizing labile proteins control the transcript stability, and (c) a shift from a posttranscriptional to a predominant transcriptional control of GM-CSF gene expression occurs during activation.
Razanajaona
D
D
Institut National de la Santé et de la Recherche Médicale U119, Marseille, France.
Maroc
C
C
Lopez
M
M
Mannoni
P
P
Gabert
J
J
D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D006207:Half-Life; D006801:Humans; D008213:Lymphocyte Activation / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*
D012333:RNA, Messenger; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide