title: TPO/c-mpl ligand induces tyrosine phosphorylation of multiple cellular proteins including proto-oncogene products, Vav and c-Cbl, and Ras signaling molecules.
abstract: Thrombopoietin (TPO)/c-mpl ligand is a hematopoietic growth factor that stimulates proliferation and maturation of megakaryocytes. To analyze the signaling pathway downstream of the c-mpl product, we used a human megakaryoblastic cell line, Mo7e, that has been proved to be responsive to TPO in terms of DNA synthesis. In this study, we found that TPO treatment resulted in tyrosine phosphorylation of Jak-2 kinase. Moreover, it was revealed that several functional molecules involved in the Ras signaling pathway, Shc and Sos, were phosphorylated by treatment with TPO. Finally, tyrosine phosphorylation of the proto-oncogene products, Vav and c-Cbl, has been proved to be induced by TPO. These results suggest that TPO could activate several signaling pathways including the Jak/Stat pathway, the Ras pathway and possibly another pathway involving the c-Cbl proto-oncogene product.
mesh_terms: D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D053614:Janus Kinase 2; D008533:Megakaryocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000032:analysis; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D011519:Proto-Oncogenes; D011971:Receptors, Immunologic / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D013926:Thrombopoietin / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D011971:Receptors, Immunologic; D011994:Recombinant Proteins; C496618:VAV1 protein, human; D019000:Phosphotyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013926:Thrombopoietin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D018631:ras Proteins; D013936:Thymidine