Cooperation between STAT5 and phosphatidylinositol 3-kinase in the IL-3-dependent survival of a bone marrow derived cell line.
Cytokine-dependent activation of distinct signaling pathways is a common scheme thought to be required for the subsequent programmation into cell proliferation and survival. The PI 3-kinase/Akt, Ras/MAP kinase, Ras/NFIL3 and JAK/STAT pathways have been shown to participate in cytokine mediated suppression of apoptosis in various cell types. However the relative importance of these signaling pathways seems to depend on the cellular context. In several cases, individual inhibition of each pathway is not sufficient to completely abrogate cytokine mediated cell survival suggesting that cooperation between these pathways is required. Here we showed that individual inhibition of STAT5, PI 3-kinase or MEK activities did not or weakly affected the IL-3 dependent survival of the bone marrow derived Ba/F3 cell line. However, the simultaneous inhibition of STAT5 and PI 3-kinase activities but not that of STAT5 and MEK reduced the IL-3 dependent survival of Ba/F3. Analysis of the expression of the Bcl-2 members indicated that phosphorylation of Bad and Bcl-x expression which are respectively regulated by the PI 3-kinase/Akt pathway and STAT5 probably explain this cooperation. Furthermore, we showed by co-immunoprecipitation studies and pull down experiments with fusion proteins encoding the GST-SH2 domains of p85 that STAT5 in its phosphorylated form interacts with the p85 subunit of the PI 3-kinase. These results indicate that the activations of STAT5 and the PI 3-kinase by IL-3 in Ba/F3 cells are tightly connected and cooperate to mediate IL-3-dependent suppression of apoptosis by modulating Bad phosphorylation and Bcl-x expression.
Rosa Santos
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SC
The Institut Cochin de Génétique Moléculaire (ICGM), Institut National de la Santé et de la Recherche Médicale (INSERM U363), Hôpital Cochin, 27 rue du Fbg St Jacques, 75014 Paris, France.
Dumon
S
S
Mayeux
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P
Gisselbrecht
S
S
Gouilleux
F
F
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000201:enzymology; D002352:Carrier Proteins / Q000378:metabolism; D002453:Cell Cycle; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004789:Enzyme Activation; D007377:Interleukin-3 / Q000502:physiology*; D048728:MAP Kinase Kinase Kinase 1; D051379:Mice; D008894:Milk Proteins; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D050799:STAT5 Transcription Factor; D017384:Sequence Deletion; D015398:Signal Transduction / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D007377:Interleukin-3; D048728:MAP Kinase Kinase Kinase 1; D008894:Milk Proteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; C494820:Bad protein, mouse; C494812:Bcl2l1 protein, mouse; C482578:Map3k1 protein, mouse