Thrombopoietin induces tyrosine phosphorylation of a common beta subunit of GM-CSF receptor and its association with Stat5 in TF-1/TPO cells.
TF-1/TPO cells are derived from an erythroleukemia cell line, TF-1, and are absolutely dependent on either TPO or granulocyte-macrophage colony-stimulating factor (GM-CSF)/interleukin-3 (IL3) for their continuous growth and survival. To gain insight into the molecular basis of hemopoietic activities shared by TPO and GM-CSF/IL3 in TF-1/TPO cells, we studied the cross-talk between signal transduction pathways elicited by these cytokines. Stimulation of TF-1/TPO cells with TPO resulted in tyrosine phosphorylation of the TPO receptor (c-Mpl) as well as the common beta subunit (beta c) of GM-CSF/IL3 receptor complex. GM-CSF, however, induced tyrosine phosphorylation of beta c but not c-Mpl. TPO-induced tyrosine phosphorylation of beta c was time- and dose-dependent. We next examined whether or not TPO-induced tyrosine phosphorylation of beta c led to recruitment of SH2-containing molecules such as Stat5 and Shc. While GM-CSF caused association of Stat5 and Shc with beta c, TPO caused association of Stat5, but not Shc, with beta c, suggesting that TPO and GM-CSF may not induce phosphorylation of the same sets of tyrosine residues in beta c. These results suggest that activation of c-Mpl affects the signaling pathway of GM-CSF/IL3 but not vice versa.
Ooi
J
J
Third Department of Internal Medicine, Yamaguchi University School of Medicine, Japan.
Tojo
A
A
Asano
S
S
Sato
Y
Y
Oka
Y
Y
D002455:Cell Division / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006410:Hematopoiesis / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D053614:Janus Kinase 2; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism / Q000473:pathology; D008894:Milk Proteins; D010766:Phosphorylation; D011487:Protein Conformation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry* / Q000378:metabolism*; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D013926:Thrombopoietin / Q000494:pharmacology*; D015534:Trans-Activators / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains
D004268:DNA-Binding Proteins; D007377:Interleukin-3; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013926:Thrombopoietin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2