title: Induction of myeloproliferative disorder and myelofibrosis by thrombopoietin receptor W515 mutants is mediated by cytosolic tyrosine 112 of the receptor.
abstract: Constitutively active JAK2V617F and thrombopoietin receptor (TpoR) W515L/K mutants are major determinants of human myeloproliferative neoplasms (MPNs). We show that a TpoRW515 mutation (W515A), which we detected in 2 myelofibrosis patients, and the Delta5TpoR active mutant, where the juxtamembrane R/KW(515)QFP motif is deleted, induce a myeloproliferative phenotype in mouse bone marrow reconstitution experiments. This phenotype required cytosolic Y112 of the TpoR. Phosphotyrosine immunoprofiling detected phosphorylated cytosolic TpoR Y78 and Y112 in cells expressing TpoRW515A. Mutation of cytosolic Y112 to phenylalanine prevented establishment of the in vivo phenotype and decreased constitutive active signaling by Delta5TpoR and TpoRW515A, especially via the mitogen-activated protein (MAP)-kinase pathway, without decreasing Janus kinase 2 (JAK2) activation. In contrast, mutation of cytosolic Y78 to phenylalanine enhanced the myeloproliferative syndrome induced by the TpoRW515 mutants, by enhancing receptor-induced JAK2 activation. We propose that TpoR cytosolic phosphorylated Y112 and flanking sequences could become targets for pharmacologic inhibition in MPNs.
authors.affiliation: Ludwig Institute for Cancer Research, Brussels, Belgium.
authors.forename: Christian
authors.initials: C
authors.lastname: Pecquet
authors.forename: Judith
authors.initials: J
authors.lastname: Staerk
authors.forename: Ronan
authors.initials: R
authors.lastname: Chaligné
authors.forename: Valerie
authors.initials: V
authors.lastname: Goss
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Lee
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Rush
authors.forename: Joanne
authors.initials: J
authors.lastname: Van Hees
authors.forename: Hélène A
authors.initials: HA
authors.lastname: Poirel
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Scheiff
authors.forename: William
authors.initials: W
authors.lastname: Vainchenker
authors.forename: Stéphane
authors.initials: S
authors.lastname: Giraudier
authors.forename: Roberto D
authors.initials: RD
authors.lastname: Polakiewicz
authors.forename: Stefan N
authors.initials: SN
authors.lastname: Constantinescu
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D016026:Bone Marrow Transplantation; D002460:Cell Line; D049109:Cell Proliferation; D006801:Humans; D015151:Immunoblotting; D053614:Janus Kinase 2 / Q000378:metabolism; D051379:Mice; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D054448:Precursor Cells, B-Lymphoid / Q000166:cytology / Q000378:metabolism; D055728:Primary Myelofibrosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D053628:Receptors, Thrombopoietin / Q000235:genetics* / Q000378:metabolism; D014162:Transfection; D014443:Tyrosine / Q000235:genetics* / Q000378:metabolism
chemical_list: D010750:Phosphoproteins; D053628:Receptors, Thrombopoietin; D014443:Tyrosine; D053614:Janus Kinase 2