In bone marrow derived Baf-3 cells, inhibition of apoptosis by IL-3 is mediated by two independent pathways

• Published in: Oncogene Vol. 14; no. 4; pp. 425 - 430
• Main Authors: LEVERRIER, Y, THOMAS, J, PERKINS, G. R, MANGENEY, M, COLLINS, M. K. L, MARVEL, J
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 30.01.1997; Nature Publishing Group
• Subjects: Ageing, cell death; Animals; Apoptosis; Apoptosis - drug effects; Bcl-2 protein; Bcl-x protein; Biological and medical sciences; Bone Marrow; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cell Cycle - drug effects; Cell death; Cell Line; Cell physiology; Culture Media; Fundamental and applied biological sciences. Psychology; Gene expression; Growth factors; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Hematopoietic Stem Cells - physiology; Homeostasis; Interleukin 3; Interleukin-3 - pharmacology; Kinases; Kinetics; Mice; Molecular and cellular biology; Protein Biosynthesis; Proto-Oncogene Proteins - biosynthesis; Proto-Oncogene Proteins c-bcl-2 - biosynthesis; RNA, Messenger - biosynthesis; Starvation; Time Factors; Transcription; Transcription, Genetic; Signal transduction; Vertebrata; Regulation(control); Cell line; Mammalia; Interleukin 3; Cell death; Cytokine; Bone marrow; Inhibition; Apoptosis
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1200845

The inhibition of cell death by growth factors plays a key role in the maintenance of the haematopoietic system homeostasis. However the mechanisms involved in this inhibition are still poorly understood. In order to determine if inhibition of apoptosis by growth factors is dependent only on the expression of survival genes, we have studied that process in the bone marrow derived IL-3 dependent cell line Baf-3. We show that, following IL-3 starvation, mRNA and protein levels of Bcl-X but not Bcl-2 decrease rapidly preceeding the onset of death. The death of IL-3 starved cells is asynchronous, starting between 6 to 8 h with 50% death being reached after 10 to 12 h. At any time point, apoptosis can be rapidly inhibited by growth factor re-addition. This has allowed us to determine that the inhibition of apoptosis by growth factor takes place at two levels. The first one, which we have called short term inhibition, is independent of mRNA and protein synthesis i.e. it takes place in the absence of survival gene neosynthesis and can be demonstrated during the first 6 h following growth factor re-addition. The second one corresponds to long-term survival-more than 24 h survival-and is strongly correlated with the induction of Bcl-X but not Bcl-2 gene expression. This induction of Bcl-X by IL-3 is shown to be dependent on MAP-kinase activation.