Transcriptional and post-transcriptional regulation of granulocyte-macrophage colony-stimulating factor production in human growth factor dependent M-07e cells.
To elucidate the regulatory mechanisms of granulocyte-macrophage colony-stimulating factor (GM-CSF) production in human myeloid leukaemic cells we studied GM-CSF gene transcription, mRNA expression and GM-CSF secretion in human growth factor dependent M-07e cells. GM-CSF transcript was detected in cells cultured in the presence of interleukin-3 (IL-3). GM-CSF or mast cell growth factor (MGF), whereas it was undetectable in growth factor deprived cells. Growth factor re-addition induced, within 2 h, the appearance of GM-CSF mRNA. Nuclear run-on experiments demonstrated that the increase of GM-CSF mRNA levels depends on GM-CSF gene transcription. The simultaneous addition, to deprived cells, of the growth factor, and of cycloheximide (CHX) for 2 h inhibited GM-CSF mRNA expression, suggesting the requirement for newly made proteins for GM-CSF gene transcription. By means of the M-07e bioassay, which allows the detection of GM-CSF, IL-3 and MGF activities, and neutralizing antibodies to each of these factors, GM-CSF activity was detected in the cell-free extract of both IL-3- and MGF-sustained cells and of cells deprived for 24 h. This finding demonstrates that M-07e cells produce and store biologically active GM-CSF in response to both IL-3 and MGF. In contrast, analysis of the growth stimulatory activity present in the culture supernatants revealed that MGF, unlike IL-3, is able to induce the secretion of consistent amounts of GM-CSF. Taken together, our results suggest that, in M-07e cells, GM-CSF gene transcription and GM-CSF production are mediated, unlike its secretion, by mechanisms shared by IL-3 and MGF.
Brizzi
M F
MF
Dipartimento di Scienze Biomediche e Oncologia Umana, Università di Torino, Italy.
Rossi
P R
PR
Rosso
A
A
Avanzi
G C
GC
Pegoraro
L
L
D015152:Blotting, Northern; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics* / Q000378:metabolism; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D007951:Leukemia, Myeloid / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D019089:Stem Cell Factor; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000378:metabolism
D016298:Hematopoietic Cell Growth Factors; D007377:Interleukin-3; D012333:RNA, Messenger; D019089:Stem Cell Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide