Lack of correlation between growth of TF-1 cells and tyrosine phosphorylation signals in response to IL-3, IL-5 and GM-CSF.
The human cell line, TF-1, was used to compare responses to interleukin 3 (IL-3), IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF). TF-1 cells grew well in the presence of any one of the cytokines in early passages. However, the level of tyrosine phosphorylation was minimal in response to IL-5, and detection of a tyrosine phosphorylation signal required high concentrations of IL-5. When grown for longer periods of time in the presence of one of the cytokines, there were dramatic difference in the cells' responses. IL-3 or GM-CSF-grown cells showed only half of the original bioassay response to IL-5. However, cells grown in IL-5 alone kept the same response, and all cells showed the same response to IL-3 and GM-CSF. IL-5-grown cells also had an increased tyrosine phosphorylation signal, along with increased sensitivity to IL-5, yet there was no difference in an IL-5 bioassay. The relative level of detection of tyrosine phosphorylated JAK-2, STAT-5, SHC, and other substrates corresponded to the overall tyrosine phosphorylation signal. IL-5-grown cells had approximately 10-fold more IL-5 receptor alpha subunit message compared to IL-3-grown. These results suggest that response of TF-1 cells to IL-5 may be deceiving in that a good response in a bioassay can be observed with relatively little tyrosine phosphorylation, but an increase in tyrosine phosphorylation can be correlated with an increase in the expression of IL-5 receptor alpha subunit.
Ettinger
S
S
Department of Medicine, University of British Columbia, Jack Bell Research Centre, Vancouver, Canada.
Fong
D
D
Duronio
V
V
D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D007377:Interleukin-3 / Q000494:pharmacology*; D015848:Interleukin-5 / Q000494:pharmacology*; D053614:Janus Kinase 2; D004915:Leukemia, Erythroblastic, Acute / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D008894:Milk Proteins; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000187:drug effects* / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D018123:Receptors, Interleukin / Q000378:metabolism; D053649:Receptors, Interleukin-5; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D014162:Transfection
D004268:DNA-Binding Proteins; D007377:Interleukin-3; D015848:Interleukin-5; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2