title: Thrombopoietin induces tyrosine phosphorylation of Stat3 and Stat5 in human blood platelets.
abstract: Thrombopoietin is known to be essential for megakaryocytopoiesis and thrombopoiesis. Recently, we and others have shown that thrombopoietin induces rapid tyrosine phosphorylation of Jak2 and other proteins in human platelets and BaF3 cells, genetically engineered to express c-Mpl, a receptor for thrombopoietin. The Jak family of tyrosine kinases are known to mediate some of the effects of cytokines or hematopoietic growth factors by recruitment and tyrosine phosphorylation of a variety of Stat (signal transducers and activators of transcription) proteins. Hence, we have investigated whether Stat proteins are present in platelets and, if so, whether they become tyrosine phosphorylated in response to thrombopoietin. We immunologically identified Stat1, Stat2, Stat3, and Stat5 in human platelet lysates. Thrombopoietin induced tyrosine phosphorylation of Stat3 and Stat5 in these cells. Thrombopoietin also induced tyrosine phosphorylation of Stat3 and Stat5 in FDCP-2 cells genetically engineered to constitutively express human c-Mpl. Thus, our data indicate that Stat3 and Stat5 may be involved in signal transduction after ligand binding to c-Mpl and that this event may have a role in megakaryopoiesis/thrombopoiesis or possibly a mature platelet function such as aggregation.
authors.affiliation: Department of Internal Medicine, Keio University, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Miyakawa
authors.forename: A
authors.initials: A
authors.lastname: Oda
authors.forename: B J
authors.initials: BJ
authors.lastname: Druker
authors.forename: H
authors.initials: H
authors.lastname: Miyazaki
authors.forename: M
authors.initials: M
authors.lastname: Handa
authors.forename: H
authors.initials: H
authors.lastname: Ohashi
authors.forename: Y
authors.initials: Y
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004837:Epinephrine / Q000494:pharmacology; D006629:Hirudins / Q000494:pharmacology; D006801:Humans; D053614:Janus Kinase 2; D051379:Mice; D008894:Milk Proteins; D009363:Neoplasm Proteins; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D050800:STAT6 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects; D013926:Thrombopoietin / Q000494:pharmacology*; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection; D014443:Tyrosine / Q000096:biosynthesis*
chemical_list: D004268:DNA-Binding Proteins; D006629:Hirudins; D008894:Milk Proteins; D009363:Neoplasm Proteins; D010975:Platelet Aggregation Inhibitors; D011518:Proto-Oncogene Proteins; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; C494080:Stat1 protein, mouse; C494085:Stat2 protein, mouse; C494087:Stat3 protein, mouse; C494100:Stat6 protein, mouse; D015534:Trans-Activators; C082218:MPL protein, human; D014443:Tyrosine; D013926:Thrombopoietin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D001241:Aspirin; D004837:Epinephrine