title: A dose-dependent tug of war involving the NPM1 leukaemic mutant, nucleophosmin, and ARF.
abstract: In acute myeloid leukaemia (AML), nucleophosmin-1 (NPM1) mutations create a nuclear export signal (NES) motif and disrupt tryptophans at NPM1 C-terminus, leading to nucleophosmin accumulation in leukaemic cell cytoplasm. We investigated how nucleophosmin NES motifs (two physiological and one created by the mutation) regulate traffic and interaction of mutated NPM1, NPM1wt and p14(ARF). Nucleophosmin export into cytoplasm was maximum when the protein contained all three NES motifs, as naturally occurs in NPM1-mutated AML. The two physiological NES motifs mediated NPM1 homo/heterodimerization, influencing subcellular distribution of NPM1wt, mutated NPM1 and p14(ARF) in a 'dose-dependent tug of war' fashion. In transfected cells, excess doses of mutant NPM1 relocated completely NPM1wt (and p14(ARF)) from the nucleoli to the cytoplasm. This distribution pattern was also observed in a proportion of NPM1-mutated AML patients. In transfected cells, excess of NPM1wt (and p14(ARF)) relocated NPM1 mutant from the cytoplasm to the nucleoli. Notably, this distribution pattern was not observed in AML patients where the mutant was consistently cytoplasmic restricted. These findings reinforce the concept that NPM1 mutants are naturally selected for most efficient cytoplasmic export, pointing to this event as critical for leukaemogenesis. Moreover, they provide a rationale basis for designing small molecules acting at the interface between mutated NPM1 and other interacting proteins.
authors.affiliation: Section of Haematology and Immunology, Department of Clinical and Experimental Medicine, University of Perugia, IBiT Foundation, Fondazione IRCCS Biotecnologie nel Trapianto, Perugia, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Bolli
authors.forename: M F
authors.initials: MF
authors.lastname: De Marco
authors.forename: M P
authors.initials: MP
authors.lastname: Martelli
authors.forename: B
authors.initials: B
authors.lastname: Bigerna
authors.forename: A
authors.initials: A
authors.lastname: Pucciarini
authors.forename: R
authors.initials: R
authors.lastname: Rossi
authors.forename: R
authors.initials: R
authors.lastname: Mannucci
authors.forename: N
authors.initials: N
authors.lastname: Manes
authors.forename: V
authors.initials: V
authors.lastname: Pettirossi
authors.forename: S A
authors.initials: SA
authors.lastname: Pileri
authors.forename: I
authors.initials: I
authors.lastname: Nicoletti
authors.forename: B
authors.initials: B
authors.lastname: Falini
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics / Q000502:physiology*; D000208:Acute Disease; D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D003593:Cytoplasm / Q000378:metabolism; D019281:Dimerization; D016503:Drug Delivery Systems; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells / Q000378:metabolism; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D049790:Nuclear Export Signals / Q000235:genetics* / Q000502:physiology; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000090243:Nucleophosmin; D025941:Protein Interaction Mapping; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D025803:Tumor Suppressor Protein p14ARF / Q000737:chemistry* / Q000378:metabolism
chemical_list: C000716967:NPM1 protein, human; D009363:Neoplasm Proteins; C000715570:Npm1 protein, mouse; D049790:Nuclear Export Signals; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D025803:Tumor Suppressor Protein p14ARF; D000090243:Nucleophosmin