title: Involvement of SH2-containing phosphotyrosine phosphatase Syp in erythropoietin receptor signal transduction pathways.
abstract: Erythropoietin (Epo) regulates the proliferation and differentiation of erythroid precursors. The phosphorylation of proteins at tyrosine residues is critical in the growth signaling induced by Epo. This mechanism is regulated by the activities of both protein-tyrosine kinases and protein tyrosine phosphatases. The discovery of phosphotyrosine phosphatases that contain SH2 domains suggests roles for these molecules in growth factor signaling pathways. We found that Syp, a phosphotyrosine phosphatase, widely expressed in all tissues in mammals became phosphorylated on tyrosine after stimulation with Epo in M07ER cells engineered to express high levels of human EpoR. Syp was complexed with Grb2 in Epo-stimulated M07ER cells. Direct binding between Syp and Grb2 was also observed in vitro. Furthermore, Syp appeared to bind directly to tyrosine-phosphorylated EpoR in M07ER cells. Both NH2-terminal and COOH-terminal SH2 domains of Syp, made as glutathione S-transferase fusion proteins, were able to bind to the tyrosine-phosphorylated EpoR in vitro. These results suggest that Syp may be an important signaling component downstream of the EpoR and may regulate the proliferation and differentiation of hematopoietic cells.
authors.affiliation: Department of Medicine (Hematology/Oncology), Indiana University School of Medicine, Indianapolis 46202.
authors.forename: T
authors.initials: T
authors.lastname: Tauchi
authors.forename: G S
authors.initials: GS
authors.lastname: Feng
authors.forename: R
authors.initials: R
authors.lastname: Shen
authors.forename: M
authors.initials: M
authors.lastname: Hoatlin
authors.forename: G C
authors.initials: GC
authors.lastname: Bagby
authors.forename: D
authors.initials: D
authors.lastname: Kabat
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: H E
authors.initials: HE
authors.lastname: Broxmeyer
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002460:Cell Line; D066246:ErbB Receptors / Q000378:metabolism; D004921:Erythropoietin / Q000494:pharmacology*; D051380:GRB2 Adaptor Protein; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D010766:Phosphorylation; D019000:Phosphotyrosine; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D017467:Receptors, Erythropoietin / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D017467:Receptors, Erythropoietin; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D004921:Erythropoietin; D019000:Phosphotyrosine; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D066246:ErbB Receptors; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases