title: Polycythaemia-inducing mutations in the erythropoietin receptor (EPOR): mechanism and function as elucidated by epidermal growth factor receptor-EPOR chimeras.
abstract: Primary familial and congenital polycythaemia (PFCP) is a disease characterized by increased red blood cell mass, and can be associated with mutations in the intracellular region of the erythropoietin (EPO) receptor (EPOR). Here we explore the mechanisms by which EPOR mutations induce PFCP, using an experimental system based on chimeric receptors between epidermal growth factor receptor (EGFR) and EPOR. The design of the chimeras enabled EPOR signalling to be triggered by EGF binding. Using this system we analysed three novel EPOR mutations discovered in PFCP patients: a deletion mutation (Del1377-1411), a nonsense mutation (C1370A) and a missense mutation (G1445A). Three different chimeras, bearing these mutations in the cytosolic, EPOR region were generated; Hence, the differences in the chimera-related effects are specifically attributed to the mutations. The results show that the different mutations affect various aspects related to the signalling and metabolism of the chimeric receptors. These include slower degradation rate, higher levels of glycan-mature chimeric receptors, increased sensitivity to low levels of EGF (replacing EPO in this system) and extended signalling cascades. This study provides a novel experimental system to study polycythaemia-inducing mutations in the EPOR, and sheds new light on underlying mechanisms of EPOR over-activation in PFCP patients.
authors.affiliation: Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.
authors.forename: Mor
authors.initials: M
authors.lastname: Gross
authors.forename: Nathalie
authors.initials: N
authors.lastname: Ben-Califa
authors.forename: Mary F
authors.initials: MF
authors.lastname: McMullin
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Percy
authors.forename: Celeste
authors.initials: C
authors.lastname: Bento
authors.forename: Holger
authors.initials: H
authors.lastname: Cario
authors.forename: Milen
authors.initials: M
authors.lastname: Minkov
authors.forename: Drorit
authors.initials: D
authors.lastname: Neumann
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D018389:Codon, Nonsense; D004252:DNA Mutational Analysis; D066246:ErbB Receptors / Q000235:genetics; D006031:Glycosylation; D006801:Humans; D066298:In Vitro Techniques; D053614:Janus Kinase 2 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D020125:Mutation, Missense; D011086:Polycythemia / Q000151:congenital* / Q000235:genetics; D011134:Polysaccharides / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D017467:Receptors, Erythropoietin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000502:physiology; D017384:Sequence Deletion; D015398:Signal Transduction / Q000235:genetics; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D018389:Codon, Nonsense; D011134:Polysaccharides; D017467:Receptors, Erythropoietin; D011993:Recombinant Fusion Proteins; D050799:STAT5 Transcription Factor; C512478:EGFR protein, human; D066246:ErbB Receptors; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D046988:Proteasome Endopeptidase Complex
keywords: chimeric receptors; erythrocytosis; erythropoietin receptor; myeloproliferative disorder