title: JAK2 associates with the erythropoietin receptor and is tyrosine phosphorylated and activated following stimulation with erythropoietin.
abstract: Erythropoietin (EPO) regulates the proliferation and differentiation of erythroid cells through interaction with its receptor (EPOR). Although EPOR is a member of the cytokine receptor superfamily and lacks a kinase domain, EPO induces tyrosine phosphorylation, which is correlated with gene transcription and mitogenesis. Here we demonstrate that EPO induces tyrosine phosphorylation of JAK2 kinase and activates its in vitro autophosphorylation. Using EPOR mutants, phosphorylation and activation of kinase activity correlate with the induction of mitogenesis. Furthermore, JAK2 physically associates with a membrane-proximal region of the EPOR cytoplasmic domain that is required for biological activity. The results support the hypothesis that JAK2 is the kinase that couples EPO binding to tyrosine phosphorylation and mitogenesis.
authors.affiliation: Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105.
authors.forename: B A
authors.initials: BA
authors.lastname: Witthuhn
authors.forename: F W
authors.initials: FW
authors.lastname: Quelle
authors.forename: O
authors.initials: O
authors.lastname: Silvennoinen
authors.forename: T
authors.initials: T
authors.lastname: Yi
authors.forename: B
authors.initials: B
authors.lastname: Tang
authors.forename: O
authors.initials: O
authors.lastname: Miura
authors.forename: J N
authors.initials: JN
authors.lastname: Ihle
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002455:Cell Division; D004789:Enzyme Activation; D004921:Erythropoietin / Q000378:metabolism*; D053614:Janus Kinase 2; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
chemical_list: D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin; D011993:Recombinant Fusion Proteins; D004921:Erythropoietin; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2